Radio-opaque organic-inorganic hybrid comprising an inorganic oxide and a polymer

Background of the invention

Hybrid materials made of organic and inorganic components linked by covalent bonds are well-known in the art (Yano.S., et al, Mater. ScL Eng., C 1998, 6, 75-81).

In the field, said materials are named "ceramers" (CERAmics and polyMERS) and "ormo- cers" (ORGanically Modified CERamicS).

Said materials are investigated and applied thanks to their good mechanical, thermal, electric and magnetic properties, arising from the combination of the characteristics of the single components.

The properties of the hybrid are particularly interesting when the inorganic component has nanometric size. Said characteristic confers to the hybrid distinctive features and originates new optical properties (Caseri, W., Macromol. Rapid Commun. 2000, 21, 705-722).

Some inorganic oxides, thanks to their radio-opacity, are used in the medical field and in all the fields wherein the protection from environmental radiation is required.

In particular, in health field, radio-opacity of given materials is used to protect individuals from the exposure to X-ray (physicians and patients), and to trace materials used, for example, in endoprosthesis.

The problem of radio-protection is particularly felt, se for example US 2004/0041107Al.

While sheltering environments from radiations is solved with works of civil engineering, the shielding of individuals needs several elements to be taken into account.

In particular, individuals standing close to radioactive elements, for example in the field of nuclear medicine, or exposed to X-ray sources, in the diagnostic and therapeutic field, should have adequate protection instruments at their disposal.

It is easy to understand that for such workers the first and most commonly used shelter from radiations is the outerwear.

Radio-opaque textiles, obtained by different techniques, are known in the art.

Commonly, a radio-opaque material is loaded on the textile, using different fixing techniques. Not always satisfactory results are achieved and the person skilled in the art has several prob-

lems in providing a radio-opaque textile having good fitting, which means being not too stiff after being impregnated with the radio-opaque material, being comfortable, in particular breathable, preserving his radio-opacity after washing and sterilization.

This problem is particularly felt by surgeons who need to be free to move and wear good- fitting clothes as well as by sanitary staff in general and patients undergoing therapies or diagnostics based on high-energy radiations.

The above mentioned patent application US 2004/0041107Al discloses a system for attenuating radiations comprising a polymeric resin and a material dispersed in the resin being capable of weaken radiations.

The radio-opaque material is dispersed in the polymer by a co-extrusion technique. Alternatively, the radio-opaque material is mixed with the polymeric matrix before the extrusion step.

A similar technique is disclosed in WO 2004/021811 wherein a radio-opaque textile finishing is obtained by impregnating it with a solution of an inorganic salt.

The patent US 6,459,091 discloses radio -protective garments obtained by impregnating a tex- tile with a light inorganic radio-opaque material (in comparison with the heavy commonly used lead derivatives).

The impregnation is obtained by immersing the textile in a solution of the radio-opaque material in the presence of an additive (adhesive, fixative, emulsifying).

WO 89/00831 discloses the formation of protective shelters resistant to ionizing radiations ob- tained by mixing a polymeric matrix with a radio-opaque filler and suitable additives.

US 7,083,644 discloses radiation-resistant (for sterilization purposes) textile implantable prostheses characterized by a particular naphthalene dicarboxylate polymer.

WO 03/093357 discloses a composition suitable for coating different medical materials with good adhesion to the substrate. The mixture is quite complex and comprises a hydrophilic polymer in aqueous solution, a colloidal metal oxide and a cross-linking agent.

Radio-opacity is obtained by adding to the mixture suitable auxiliary agents. Reported applications of said mixture do not include radio -protective outerwear.

Mixtures of polymers and radio-opaque material are disclosed in US 7,196,023.

Finally, WO 2006/069007 discloses compositions and methods for the production of radio- opaque polymeric articles by mixing a radio-opaque material with a powdery or pelletized polymer, or a solution, emulsion or liquid suspension of the polymer in water or in a solvent. Radio -protective garments are disclosed. Better results are achieved by using nanomaterials. This document provides three processes for the incorporation of the nanomaterials in the polymeric mixture: direct mixing of the polymer and the nano material, as discrete phases or in solution; or by in situ polymerization in the presence of the nanomaterial; or by formation of the nanomaterial in the presence of the polymer, which acts as a surfactant in the formation of nanoparticles without the formation of covalent bonds between the two phases. The applica- tion of the mixture on textiles is made by spraying, adhesion or coating.

The optimal radio-opaque material should be permanently fixed to the textile, in order to avoid its dispersion into the environment (dusting effect) and be resistant to washing and sterilization, if necessary. Furthermore, in order to ensure breathability of the garment, the radio- opaque material should not form a continuous coating, thus closing the textile's pores.

The patent EP 0 918 061 discloses hybrid organic-inorganic polymers, wherein the polymer is selected from aromatic polycarbonates and aromatic polyesters in order to provide hybrids having a hydrophobic polymeric part and a resulting material with suitable mechanical characteristic, for the application in the field which are intended to.

Hybrid application covers several fields concerning-plastic materials, in particular molded ar- tides, films, sealing agents and adhesives, material for adhesive or coating, construction materials, optical materials, medical devices, but no indication is given on their possible use in the field of textiles. Moreover, said patent solves some problems related to the process of preparation of the hybrids deriving from the use of hydrophobic polymers.

Summary of the invention

It has now been found that an organic-inorganic hybrid, namely a ceramer, formed by an organic polymeric part and an inorganic part, meets the needs experienced in the state of the art. In particular, said hybrid is made by of a polymeric part, which gives suitable mechanical properties, such as flexibility, and by an inorganic part that is responsible for the desired ra- diopacity and, when the phase dimension is within the nanometric scale, the hybrid is trans- parent to the visible light.

Surprisingly, the hybrid, according to the present invention, can be used in textile finishing during manufacturing of textile articles, which protect living subjects from radiation. The hybrid, according to the present invention, confers to the textile an optimal coating of each sin-

gle fiber, following the textile's structure, preserving its fitting and breathability. The ceramer according to the present invention is resistant to washing and sterilization.

The object of the present invention is an organic-inorganic hybrid consisting of: 1) an inorganic oxide and 2) a polymer selected from the group consisting of aliphatic polyester, ali- phatic polyetherester, aliphatic polycarbonate, polyethercarbonate and co-polymers thereof. In said hybrid, the polymer and the inorganic oxide are linked by covalent bonds.

The hybrid, object of the present invention, offers several advantages which will become evident from the detailed description of the invention.

The material provided by the present invention, is able to combine good workability, flexibil- ity and low density of polymers with hardness, rigidity, thermal and chemical stability of inorganic oxides.

The new and interesting characteristics of said materials are due to the presence of inorganic domains of nanometric/micrometric size linked to the organic phase by covalent bonds.

Conveniently, the hybrid of the present invention can be used in the fields which require ra- dio-opaque materials to adequately protect from radiations, or to radiopacify, i.e. to make traceable in the presence of a radioactive source, an article containing the hybrid.

The hybrids of the present invention have radio-opacity and UV-blocking properties (due to the inorganic phase), and, when the inorganic phase is in the nanometric domain, transparency to visible light.

The hybrids of the present invention, as previously underlined, have mechanical properties (flexibility and ductility) associated with the organic polymeric phase^ which are completely different from the properties of the pure inorganic phase; the hybrid structure confers material properties which are much more suited for surface coating applications, than the presently known solutions.

The physical-mechanical properties of the hybrid can be modulated by changing the ratio between the organic and inorganic phases, and by acting on the nature, microstructure and polymerization degree of the polymeric component.

The presence of a covalent bond between the phases permits the "anchorage" of the inorganic particles avoiding their unwanted release.

For example, this undesired leaching can happen in biomedical devices wherein radio-opacity is conferred by heavy metal salts dispersed in the polymeric matrix or in textiles treated with traditional finishing systems during the washing steps.

A further advantage of the hybrid of the present invention is that it is easy to apply when used in coatings. Furthermore, said coating has higher elasticity and flexibility in comparison with any plain inorganic coating. The optimal adhesion to metallic substrates and polymers together with the easy applicability represents a further advantage, which makes the hybrid applicable to surfaces of different nature. Hybrid formulations wherein both the organic phase and the inorganic phase are biocompatible can advantageously used for coating endoprosthe- sis, as for example stents.

It will be evident from the detailed description, that the hybrid provided by the present invention leads to a stable chemical "anchorage" of the coating on the substrate, in case of substrate with reactive groups, being this aspect more desirable that the simple deposition.

Another advantage of the hybrid of the present invention is the low cost of its components and reduced time of synthesis and time of application of the coating.

Another application is in the field of technical/smart textiles. The invention can confer the above mentioned properties (radio-opacity, transparency, UV-fϊltering) to textiles and garments by a simple finishing procedure. The presence of a polymeric phase in the hybrid reduces the stiffening effect of the ceramic inorganic phase, which is anyway responsible for the functional properties, assuring flexibility and tactile pleasantness to the hybrid-coated fabric. The so obtained textiles can be applied in the hospital for staff exposed to ionizing radiations (X-ray). For example, not only the personnel performing angioplasty operations, but also the patients who are exposed to the radiations for diagnostic or therapeutic purposes can benefit from the use of comfortable protective wear.

The present invention gives the opportunity to manufacture protective outerwear with good fitting and easy use.

The material is proposed also as a coating for endo-prosthetic devices which require a radiographic traceability. Said coating is made by polymers and metallic oxides commonly used in the biomedical field and, for this reason, their use for coating for example coronary stents in- stead of presently used noble metals (Au or Ta) can be proposed.

Moreover, the application of said coating does not alter the massive properties of the material, like when the material is made of polymers mixed with radio- opacifying additives (Barium salts, etc).

The materials object of the present invention are produced by the sol-gel technique, starting both from commercially available products and from products which can be prepared by known techniques, and have been characterized using DSC, TGA, FT-IR Spectroscopy and UV- Vis, SEM.

The material, in the form of a sheet (thickness 0.1-0.4 mm) or of a coated cotton fabric, underwent radiographic investigation (using a mammography instrument), and gave distinct radiographic images which demonstrate radio-opacity of the object.

The transparency to visible light of the material of the present invention is due to nano metric size of the inorganic oxide domains.

The materials, in the form of thin coating on a polyolefϊn substrate, were investigated with UV- Vis spectroscopy. The hybrids are capable to completely absorb UV-radiation under threshold values ranging from 320 nm to 340nm, therefore acting as UV filters.

Thus, it is an object of the present invention an organic-inorganic hybrid consisting of: 1) an inorganic oxide, 2) a polymer selected from the group consisting of aliphatic polyester, ali- phatic polyetherester, aliphatic polycarbonate, aliphatic polyethercarbonate and copolymer thereof, wherein the oxide and the polymer are linked by a covalent bond.

In particular, it is an object of the present invention an organic-inorganic hybrid, as previously defined, wherein the polymer is represented by the following formulae:

(I) wherein:

R is selected from the group consisting of H, OH, a fragment of initiator/catalyst deriving from the starting polymer, or wherein Rs and R9, which can be the same or dif- ferent, are hydrogen or a linear or branched Ci-Cs alkyl group and X is selected from the group consisting of O, S and NH;

a is selected from 0,1,2,3,4 and 5;

b is selected from 0 and 1 ;

c is selected from 0,1,2,3,4 and 5;

d is selected from 0,1,2,3,4 and 5;

e is selected from O and 1 ;

being a, b, c, d and e the same or different in the two blocks n and m;

R ₁ , R ₂ , R3, R ₄ , which can be the same or different, are H, (CH ₂ )kCH3, wherein k is selected from the group consisting of 0,1,2,3,4 and 5, or Ri and R ₂ are linked each other to form a cycloalkylene;

R5 is selected from the group consisting of -(CReRy)I-, wherein 1 is an integer from 1 to 20, wherein R ₆ and R ₇ , which can be the same or different, are hydrogen or a linear or branched C ₁ -C ₈ alkyl group, and a -[(CRsR9) _P -X] _r - wherein Rs and R9, which can be the same or different, are hydrogen or a linear or branched Ci-Cs alkyl group, , and X is selected from the group consisting of O, S and NH, wherein r is an integer ranging from 1 to 100 and p is an integer ranging from 1 and 10;

(H)

wherein:

R is selected from the group consisting of H, OH, a fragment of initiator/catalyst deriving from the starting polymer, or -(CR9Rio) _P -X- wherein R9 and Rio, which can be the same or different, are hydrogen or a linear or branched Ci-Cs alkyl group and X is selected from the group consisting of O, S and NH;

a is selected from the group consisting of 0,1,2,3,4 and 5;

b is selected from the group consisting of 0 and 1 ;

c is selected from the group consisting of 0, 1 ,2,3 ,4 and 5 ;

d is selected from the group consisting of 0,1,2,3,4 and 5;

e is selected from the group consisting of 0 and 1;

f is selected from the group consisting of 0,1,2,3,4 and 5;

being a and c the same or different in the two portions of the molecule:

R ₁ , R ₂ , R3, R ₄ , R5, Re, R7, R8 the same or different each other, are H, (CH ₂ )kCH3, wherein k is selected from the group consisting of 0, 1 ,2,3,4 and 5;

A further object of the present invention is a process for the preparation of the hybrid and the hybrid obtainable form said process.

A further object of the present invention is a material comprising said hybrid, in particular a radio-opaque and UV-absorbing material. The uses of said material are further objects of the present invention as well as the articles comprising said material.

Furthermore, another object of the present invention is a composite which comprises the above hybrid in combination with other substances for specific uses. An example of said composite is the combination between the hybrid with silver salts to confer antibacterial activity. Said composite can be interestingly used in the medical field, where the combination of radio-opacity with the antibacterial activity can be desirable, for example in case of a textile for medical use and of an endoprosthesis for diagnostic or therapeutic use.

The present invention will be now illustrated in detail through examples and figures.

In the figures:

Figure 1 : FT-IR spectra of PBG (solid line) and of the hybrid El-b (dotted line), disclosed in example 1;

Figure 2: the UV- Vis spectra of: a) polypropylene (film thickness 31 μm); b) PP-El-a (coating thickness: 6 μm); c) PP-E 1-b (coating thickness: 5 μm); d) PP-E 1-c (coating thickness: 4μm); e) solution of PBG in THF, as disclosed in example 1;

Figure 3: SEM images with different magnifications (xlOO and xl,000, indicated in the Fig- ure) of the cotton fabric before (a and c) and after coating with the hybrid of the present invention (b and d, sample Cot-E2-b).

Figure 4: FT-IR spectra of PTMC (solid line) and of the hybrid E6-b (dotted line), disclosed in example 6.

Figure 5: FT-IR spectra of PCL (solid line) and of the hybrid E12-b (dotted line), disclosed in example 12.

Detailed description of the invention

The metal oxides constituting the inorganic part of the hybrid, according to the present inven- tion, are known in the field of hybrids and of radio -opaque additives, as for example disclosed in the patent literature cited before.

In a first preferred embodiment of the invention, the inorganic oxide is selected from the group consisting of oxides of transition metals of the Periodic Table of Elements and of Group IV A. Preferably, said oxide is selected from the group consisting of Yttrium oxide, Cerium oxide, Tantalum oxide, Hafnium oxide, Molybdenum oxide and Niobium oxide, more preferably, the oxide is selected from the group consisting of Zirconium oxide (zirconia) and Titanium oxide (titania).

Said oxides give the hybrid comprising them desired properties such as radio-opacity and capability of absorbing UV-radiation, in addition to mechanical properties suitable for applica- tions other than radio-protection and radio -traceability.

The polymer used in the present invention is an aliphatic polyester, aliphatic polyetherester, aliphatic polycarbonate, polyethercarbonate and copolymers thereof as defined by the above formulae.

The polymer or copolymer used has a molecular weight Mn of at least 200 and has virtually no upper limit, in view of practical considerations, such as viscosity. Preferably, the molecular weight can be up to 300,000 Da. The polymer can be hydroxy-terminated.

As to the definition of group R in formula (I) and (II) above, other than hydrogen or hydroxyl or the alkyl group reported in the above formulae, R can be a fragment of initiator or catalyst. In the context of the present invention, the term "fragment of initiator or catalyst" is under- stood by the person of ordinary skill in polymers as a weakly basic compound such as amine, metal oxide, alkoxide and acetates, or acetates of Ca, Mg, Zn, Cd, Pb and Co [H. Kόpnick, M. Schmidt, W. Brugging, J. Rϋter, W. Kaminsky, "Polyesters" in Ullmann's Encyclopedia of Industrial Chemistry, 7 ^th Edition, J. Whiley and Sons, 2008.]. These groups may be present in commercially available polymers. Examples of "fragment of initiator or catalyst" are found in patent and non-patent literature, see for example a) D.E. Perrin, J.P. English "Polyglycolide and Polylactide" in Handbook of Biodegradable Polymers, A.J. Domb, J. Kost and D. M. Wiseman Eds., Harwood Academic Publishers, 1997, Amsterdam, Pag. 3; b) R.S. Bezwada, D.D. Jamiolkowski, K. Cooper "Poly(p-dioxanone) and its copolymers" in Handbook of Bio-

degradable Polymers, A.J. Domb, J. Kost and D.M. Wiseman Eds., Harwood Academic Publishers, 1997, Amsterdam, Pag. 29; c) P. Dobrzynski J. Polym. ScL Part A, 42, 1886-1900 (2004); d) Z. Jenlinski, W. Walach, P. Kurcok, G. Adamus Makromol Chem. 192, 2051-2057 (1991).

In a preferred embodiment of the invention, said aliphatic polyester or polyetherester is selected from the group consisting of polylactic acid, polygly colic acid, polyhydroxybutirric acid, polycaprolactone, polydioxanone, polypivalolactone, polyethyleneadipate, polybuthyl- eneadipate, polybuthyleneglutarate, polyethyleneglutarate, polyethylensebacate, poly- buthylensebacate, polydiethyleneglycoladipate, polyethyleneglycolglutarate, while said ali- phatic polycarbonate or polyetherecarbonate is polyethylenecarbonate, polytrimethylenecar- bonate, polyhexamethylenecarbonate, poly(2,2-dimethyl) propylenecarbonate, polycyclohex- anecarbonate, poly(ethylene ether-carbonate), poly(propylene ether-carbonate).

In a more preferred embodiment of the invention, the hybrid is formed by one of the above cited polymers and Titanium oxide (titania).

The process for the preparation of the hybrid of the present invention comprises the preparation of an inorganic oxide in the presence of the selected polymer.

The inorganic oxide is prepared according to the sol-gel method. Said method is well-known to the person of ordinary skill in the art and does not require particular explanation. For the sake of exemplification, reference is made to Sumio Sakka "Handbook of Sol-gel Science and Technology: Processing, Characterization, and Applications" Springier 2004 or to the above mentioned EP 0 918 061.

Generally, the process for the preparation of the hybrid of the present invention is disclosed in the following manner.

The hybrid can be represented by the scheme below.

O segment

Q$ Polymer chain

According to the process of the present invention, a solution of the polymer is added to a solution of a precursor of the inorganic oxide to give a precursor solution of the hybrid.

Preferably, the solvent of the polymer solution is the same solvent of the solution of the precursor of the inorganic oxide.

Conveniently, the solution of the precursor of the inorganic oxide preferably contains an acid, preferably an inorganic acid, for example hydrochloric acid or sulphuric acid.

In another embodiment of the present invention, the solution of the precursor of the hybrid can contain a certain amount of water as impurity.

The ratio between said polymer and the precursor of the inorganic oxide is preferably from 1/99 w/w to 99/1 w/w, preferably, better properties are obtained when said ratio is comprised between 25/75 and 75/25.

The total concentration of the polymer and of the precursor of the inorganic oxide in the solvent is comprised between 0.01 g/ml and 1 g/ml.

The final solution can provide the hybrid in the desired form, for example the solution can be cast in a mold and let cure at room temperature, till the bulk hybrid is obtained, otherwise, it can be used for coating other materials at room temperature, for example fabrics.

The hybrid can conveniently undergo a thermal treatment in order to bring the reaction to completeness. The course of the reaction can be monitored by TGA and FT-IR spectroscopy, which also allow checking its completeness.

Although it is not essential, the polymer can carry two OH groups at both chain ends.

The process for the preparation is summarized as follows:

The oxide of the metal is prepared starting from a suitable precursor, for example an alkoxide of the metal.

Hydrolysis:

M(OR) ₄ + H ₂ O -> M(OR) ₃ -OH + ROH

Condensation:

M(OR) ₃ -OH + M(OR) ₃ -OH -> (RO) ₃ M-M(OR) ₃ + H ₂ O

and/or

M(OR) ₃ -OH + M(OR) ₃ -OR -> (RO) ₃ M-M(OR) ₃ + ROH

If in the condensation phase a polymer bearing groups able covalently bind to the metal atom is added, the inorganic network will be strongly anchored to the polymer phase.

A suitable amount of polymer is weighed and dissolved in a suitable solvent, for example THF, chloroform, ethanol or 1-propanol, at room temperature (Solution 1).

In a second container a suitable amount of the precursor of the metal oxide is weighed.

In the second container, the solvent, preferably the same used for the polymer or one compatible with it, is firstly added under stirring, then an acid, for example HCl (37% w/v aqueous solution) and stirring is continued until dissolution, verifying that the solution does not become cloudy (Solution 2). The so obtained mixture is the sol of the oxide. While always stirring, solution 1 is slowly added to the oxide sol (solution 2). The so obtained mixture (so- lution 1+2) is left under stirring for a proper time. Solution 1+2 can now be applied on suitable supports, or can be cast in a mold. The mold will be in a material which allows release of the obtained object, for example PTFE-coated. The solution 1+2 is left to cure at room temperature, for example for 12-24h. The obtained solid material is treated in an oven, for example at 100-13O ⁰ C for 0.5-4h, in order to bring the crosslinking reaction to completeness and to eliminate from the hybrid the reaction coproducts and the residual solvent.

In a preferred embodiment of the process according to the invention, the titanium oxide precursor is titanium tetraisopropoxide.

In another preferred embodiment of the process according to the invention, the zirconium oxide precursor is tetrapropoxide of zirconium.

The precursors of the oxides are commercially available, or can be prepared by well-known methods.

The hybrid obtainable from the above disclosed process is a further object of the invention.

As said, it is an object of the present invention a material comprising the above disclosed hybrid.

Preferably, the material is characterized by being radio-opaque. A suitable embodiment is a radio-opaque coating, for example in the form of film. It is also comprised in the present invention a material for medical use, for example an endoprosthesis coated with a material comprising the hybrid herein disclosed. An example of endoprosthesis is a coronary stent, see EP 0 824 900 and the general literature relevant to stents; a catheter, cardiac supports and every other type of device which can be implanted in the body of a living subject, human or animal, which must be traced by means of radiography.

In a particularly preferred embodiment of the invention, the material comprising the hybrid is a tissue. This tissue is used for the manufacture of articles that must be radio-opaque. A pre- ferred field is the medical one, where the present invention finds its application for the manufacture of all those garment articles that are used in environments exposed to radiations. Examples are white coats, aprons, draw-sheets, blankets, masks, pyjamas, nightgowns, gloves and any other textile article, also comprising bandages, sheets, curtains. Preferably, the tissue is made of vegetal or animal natural fibres, such as cotton, silk, wool, or by synthetic fibres, such as polyesters or polyamides, or a mixed fiber.

The tissue is treated with the hybrid of the present invention with well-known and common finishing techniques, for example as disclosed in the patent references cited in this application.

A simple manner of applying the hybrid to the tissue is for example impregnation with the so- lution from which the hybrid is prepared (solution 1+2 disclosed above).

Thanks to the capability of the hybrids of the present invention to shield UV radiations, another possible practical use thereof is in manufacturing of fabrics of any type with the purpose to provide a protection from UV radiations.

There are particular pathologies, for example of Cockayne syndrome and xeroderma pigmen- tosus (Rapin, I, et al. Neurology, 2000, Nov 28; 55(10):1442-9), whihc require a protection as strong as possible from UV radiations. The lack of proper protection compels the affected subjects to an extremely limited outdoor stay, or even to avoid to stand near windows, unless suitably shielded or even darkened.

A further object of the present invention is the textile disclosed above for the manufacturing of garments and other accessories for the protection from UV radiations.

This embodiment can be carried out also for commonly used objects, for the general protection from UV radiations, especially for sensible subjects, in particular children. Examples of such embodiments are beach umbrellas, marquees, awnings, towels, tents.

A further object of the present invention is represented by articles comprising the hybrid herein disclosed, therefore transparent to visible light, but opaque to UV radiation. Examples according to the invention are transparent slabs, and their uses, for example, all the uses provided in building, such as slabs for closures for openings in buildings, such as doors, win- dows, shutters, or openings for the passage of the light inside environments or coverings of buildings, or for vehicle windows. In this manner, it is possible to provide suitable protection to those subjects in need of the maximum protection, or wish anyway protection, without drastically reducing natural lighting.

Another interesting embodiment is a lens for glasses, either corrective or not, for the protec- tion from UV rays.

The following examples further illustrate the invention.

Example 1 : Hybrid Polybutyleneglutarate (PBGVTitania

In the following example, the reported amounts of reactants refer to a hybrid obtained from a PBG/TIPT 25/75 feed (hybrid El -a). The quantities in brackets refer to additional syntheses of hybrids with feed composition PBG/TIPT 50/50 and 75/25 (hybrid El-b e El-c respectively).

0.5g (1.Og; 1.5g) of commercial poly(l,4-butyleneglutarate) di-hydroxy-terminated (PBG) (Aldrich, Catalogue N°: 445991, M _n 1,000 Da) are dissolved in 4ml of THF at room temperature (solution 1).

Separately 1.5g (l.Og; 0.5g) of titanium tetraisopropoxide (TIPT) (Aldrich, 99%; Catalogue N° 205273) are mixed with 1.0ml of THF and 120μl (80μl; 40μl) of HCl (aqueous solution 37%w/w, Fluka) under vigorous stirring for 2min, obtaining solution 2. Solution 1 is slowly added to solution 2 under vigorous stirring.

Mixture 1+2 is stirred for 2min, then it is poured into a PTFE coated container and kept at room temperature for 24h. The obtained material is subsequently heat treated in an oven at 110 ⁰ C for 2h, yielding hybrid samples labeled as El -a, El-b, El-c.

The three hybrids El -a, El-b, El-c have been analyzed by thermo gravimetric analysis (TGA) in air purge. The obtained results are listed in Table 1. The solid residue obtained after heating at 600 ⁰ C in the presence of oxygen, is attributed to titania. The values reported in Table 1 show a good agreement with the expected value calculated on the basis of the feed composition of mixture 1+2.

Table 1

Thermal and spectroscopic (UV) properties of hybrids El -a, El-b, El-c.

Mixture 1+2 TGA results UV-Vis results

Sample PBG/TIPT Residue at 600 ⁰ C Calculated residue λ ₂₅ ^c

(%) ^a (%) (titania)(%) ^b (nm)

El-a 25/75 45.04 45.74 337 ^d

El-b 50/50 23.15 21.94 339 ^d

El-c 75/25 11.50 8.56 321 ^d

^a Residue obtained from TGA measurements run in air from room temperature to 600 ⁰ C at heating rate 20°/min.

^b Residue calculated according to the feed composition of mixture 1+2.

^c Wavelength at which UV transmitted radiation undergoes a 75% reduction.

^d Values obtained for hybrid samples cast on PP (PP-El -a, PP-E 1-b and PP-E 1-c).

In Figure 1 FT-IR spectra of hybrid El-b and of the plain PBG polymer are compared. The hybrid spectrum shows all absorption bands of plain PBG, as well as absorptions typical of amorphous titania vibrations are observed [M. J. Velasco, F. Rubio, J. Rubio, J. L. Oteo Thermochimica Acta, 326, 91-97 (1999)]. However, hybrid spectrum is not the mere addition of the two plain component spectra (PBG and Titania), showing additional absorptions at 1535cm ^"1 and 610cm ^"1 (arrows in figure 1) attributed to bond formation between organic and inorganic phases.

In order to analyze the UV-Vis absorption properties of the hybrids, mixture 1+2 is applied as a coating on polypropylene films (PP). PP films are fully transparent to radiation in the UV range. Hybrid application on PP is obtained by dipping the PP film in the mixture 1+2 for 5sec. The coated PP samples are kept at room temperature for 24h followed by heat treatment in oven at 110 ⁰ C for Ih. The coated samples are labeled PP-El-a, PP-El-b and PP-El-c.

Figure 2 shows UV-Vis spectra of PP-El-a, PP-El-b e PP-El-c. For the sake of comparison, Figure 2 also shows the spectra of uncoated PP and of PBG (in THF solution, since no PBG coated PP film was obtained). The PP films, coated with a very thin hybrid layer (average thickness 5μm) display an excellent cut off of the radiation in the UV range. At wavelengths lower than 320/340nm, the hybrid acts as an excellent UV-filter. The wavelength values at

which the transmitted radiation intensity undergoes a 75% reduction are listed in Table 1

(λ ₂₅ ).

Example 2: Fabric treated with a hybrid coating.

Mixture 1+2, already described in Example 1, was applied to cotton fabric. Application was achieved by dipping cotton samples to be coated in mixture 1+2 for 15sec. Coated cotton samples were kept at room temperature for 24h and finally heat treated at 110 ⁰ C for Ih. At the end of the described procedure fabric samples with a hybrid coating were obtained and they were labeled as Cot-E2-a, Cot-E2-b, Cot-E2-c.

Samples Cot-E2-a, Cot-E2-b, Cot-E2-c were analyzed by TGA. The obtained results are listed in Table 2.

Table 2

Thermogravimetric results of cotton fabric samples coated with hybrid (Cot-E2-a, Cot-E2-b,

Cot-E2-c).

Sample Mixture 1+2 Hybrid load on Solid residue at Calculated

PBG/TIPT fabric ¹ 600°C ^b residue

(%) (%) (%) (titania) ⁰

(%)

Cot-E2-a 25/75 13.30 10.20 7.47

Cot-E2-b 50/50 22.72 7.08 6.43

Cot-E2-c 75/25 17.54 3.20 3.42

¹ Gravimetrically determined. b Residue obtained from TGA measurements run in air from room temperature to 600 ⁰ C at heating rate 20°/min.

^c Residue calculated according to the feed composition of mixture 1+2 and on the hybrid load on the cotton fabric.

As already discussed in Example 1 for hybrids El -a, El-b, El-c, also for samples Cot-E2-a, Cot-E2-b, Cot-E2-c the solid residue obtained in air after heating at 600 ⁰ C is related to the titania content in the analyzed sample. The measured value is in all cases in good agreement with the calculated data (that takes into account both the mixture 1+2 composition and the hybrid load on the cotton fabric). This result demonstrates that, upon deposition on the fabric,

hybrid composition stays unchanged. Consequently composition of the hybrid coated on cotton fibres can be controlled by formulation of the mixture 1+2.

Figure 3 compares scanning electron microscopy (SEM) images taken on untreated cotton fabric (a and c, images at different magnification, xlOO e x 1,000 respectively) and on cotton fabric after hybrid coating (b and d, sample Cot-E2-b). No significant differences in the aspect of the two fabrics are observed, even at magnification x 1,000 (images c and d), where single fibres belonging to the hybrid-treated yarn look well separated one from the other, as observed in the untreated sample. The fibres are seen to be individually covered by the hybrid. Hence the coating does not macroscopically and indistinctly include the whole yarn, thus ob- structing fabric porosity; on the contrary the fabric maintains the openings between yarns (see Figure 3) providing breathability and comfort.

Analogous results are obtained upon coating with the hybrid silk, wool and polyester fabrics.

Example 3: Hybrid Polybutyleneglutarate PBG/Titania

l.Og of commercial PBG are dissolved in 5ml of THF at room temperature (solution 3).

Separately 1.Og of titanium TIPT are mixed with 1.0ml of THF and 80μl of HCl 37%w/w under vigorous stirring for 2 min (solution 4). Solution 3 is slowly added to solution 4 under vigorous stirring. Mixture 3+4 is stirred for 5min. Separately a solution of H ₂ O (quantities comprised in the range of 60-180 μl) in 1.0ml of THF is prepared (solution 5). Solution 5 is slowly added to mixture 3+4 under vigorous stirring, obtaining mixture 3+4+5.

Mixture 3+4+5 is poured into a PTFE-coated container and kept at room temperature for 24h. The obtained material is subsequently heat treated in an oven at 110 ⁰ C for 2h, yielding the hybrid sample.

The hybrid FT-IR spectrum shows all absorption bands of plain PBG, as well as absorptions typical of amorphous titania vibrations. However, hybrid spectrum is not the mere addition of the two plain component spectra (PBG and Titania). Indeed it shows additional absorptions at 1535cm ^"1 and 610cm ^"1 attributed to bond formation between organic and inorganic phases.

Example 4: Hybrid Polybutyleneglutarate (PBGVTitania

0.5g (l.Og; 1.5g) of commercial poly(l,4-butyleneglutarate) di-hydroxy-terminated (PBG) are dissolved in 6ml of chloroform at room temperature (solution 6).

Separately 1.5g (l.Og; 0.5g) of titanium tetraisopropoxide (TIPT) (Aldrich, 99%; Catalogue N° 205273) are mixed with 120μl (80μl; 40μl) of HCl (aqueous solution 37%w/w, Fluka) and

2.0ml of chloroform under vigorous stirring for 2min, obtaining solution 7. Solution 6 is slowly added to solution 7 under vigorous stirring.

Mixture 6+7 is stirred for 2min, then it is poured into a PTFE coated container and kept at room temperature for 24h. The obtained material is subsequently heat treated in an oven at 110 ⁰ C for 2h, yielding hybrid samples labeled as E4-a, E4-b, E4-c.

The three hybrids E4-a, E4-b, E4-c have been analyzed by thermo gravimetric analysis (TGA) in air purge. The obtained results are listed in Table 3. The solid residue obtained after heating at 600 ⁰ C in the presence of oxygen, is attributed to titania. The values reported in Table 3 show a good agreement with the expected value calculated on the basis of the feed composi- tion of mixture 6+7.

Table 3

Thermal properties of hybrids E4-a, E4-b, E4-c.

Mixture 6+7 TGA results

Sample PBG/TIPT Residue at 600 ⁰ C ^a Calculated residue (tita¬

(%) (%) nia) (%) ^b

E4-a 25/75 43.0 45.7

E4-b 50/50 21.1 21.9

E4-c 75/25 9.9 8.6

^a Residue obtained from TGA measurements run in air from room temperature to 600 ⁰ C at heating rate 20°/min.

^b Residue calculated according to the feed composition of mixture 6+7.

The hybrid FT-IR spectrum shows all absorption bands of plain PBG, as well as absorptions typical of amorphous titania vibrations are observed. Analogously to previously discussed samples, additional absorptions attributed to bond formation between organic and inorganic phases are also observed.

Example 5 : Hybrid Polytrimethylenecarbonate (PTMC VTitania

By following the synthetic procedure in Example 1, except for the preparation of solution 1, hybrids PTMC/Titania are prepared.

Preparation of solution 1 : 0.5g (l.Og; 1.5g) of polytrimethylenecarbonate di-hydroxy- terminated (PTMC; average molecular weight 2,500Da from ¹ H-NMR spectra) synthesized

according to the literature [M. Sepulchre, M. O. Sepulchre, M. A. Dourges, and M. Neblai Macromol. Chem. Phys., 201, 1405 (2000)] are dissolved in 6ml of THF at room temperature.

The hybrid FT-IR spectrum shows all absorption bands of plain PTMC, as well as absorptions typical of amorphous titania vibrations. However, hybrid spectrum is not the mere addition of the two plain component spectra (PTMC and Titania). In addition bands at 1,090cm ^"1 and 602cm ^"1 are observed that indicate bond formation between organic and inorganic phases.

Analogously, a polytrimethylenecarbonate di-hydroxy-terminated (PTMC) with average molecular weight 3,900Da (from ¹ H-NMR spectra) and synthesized according to the literature [M. Sepulchre, M. O. Sepulchre, M. A. Dourges, and M. Neblai Macromol. Chem. Phys., 201, 1405 (2000)] was used obtaining the desired hybrid.

Example 6: Hybrid Polytrimethylenecarbonate (PTMC VTitania

By following the synthetic procedure in Example 1, except for the preparation of solution 1, hybrids PTMC/Titania are prepared. Hybrid samples are labeled as E6-a, E6-b, E6-c, according to solution 1 composition.

Preparation of solution 1 : 0,5g (l,0g; l,5g) of polytrimethylenecarbonate di-hydroxy- terminated (PTMC; average molecular weight 12,000Da from ¹ H-NMR spectra) synthesized according to the literature [M. Sepulchre, M. O. Sepulchre, M. A. Dourges, and M. Neblai Macromol. Chem. Phys., 201, 1405 (2000)] are dissolved in 6ml of THF at room temperature.

In Figure 4 FT-IR spectra of hybrid E6-b and of the plain PBG polymer are compared. The hybrid spectrum shows all absorption bands of plain PTMC, as well as absorptions typical of amorphous titania vibrations. However, hybrid spectrum is not the mere addition of the two plain component spectra (PTMC and Titania). In addition bands at 1090cm ^"1 and 602cm ^"1 (arrows in figure 4) are observed that indicate bond formation between organic and inorganic phases.

Example 7: Hybrid polydiethylenglycoleadipate PDEGA/Titania

By following the synthetic procedure of Example 1, except for the preparation of solution 1, hybrids PDEGA/Titania are prepared.

Preparation of solution 1 : 0.5g (l.Og; 1.5g) of commercial polydiethylenglycoleadipate di- hydroxy-terminated (PDEGA) (Aldrich, N° Catalogue: 458392, M _n 2,500Da) are dissolved in 6ml of THF at room temperature.

The hybrid FT-IR spectrum shows all absorption bands of plain PDEGA, as well as absorptions typical of amorphous titania vibrations. However, hybrid spectrum is not the mere addition of the two plain component spectra (PDEGA and Titania). In addition bands at 1535cm ^"1 and 610cm ^"1 are observed that indicate bond formation between organic and inorganic phases.

Example 8: Hybrid polybutyleneglutarate (PBGVZirconia

0.5g (1.Og; 1.5g) of commercial polybutyleneglutarate di-hydroxy-terminated (PBG) (Aldrich, N° Catalogue: 445991, M _n 1,000 Da) are dissolved in 6ml of THF at room temperature (so Iu- tion 8).

Separately 2.15g (1.43g; 0.72g) of a commercial solution of zirconium tetrapropoxide (TPOZ) in 1-propanol (Aldrich, 70% w/w solution, N° Catalogue 333972) are weighed (solution 9). Solution 8 is slowly added to solution 9 under vigorous stirring. The obtained mixture 8+9 is stirred for 2min.

Mixture 8+9 is poured into a PTFE-coated container and kept at room temperature for 24h. The obtained material is heat treated in an oven at 110 ⁰ C for 2h, yielding the hybrid sample.

The hybrid FT-IR spectrum shows all absorption bands of plain PBG, as well as absorptions typical of amorphous zirconia vibrations are observed. However, hybrid spectrum is not the mere addition of the two plain component spectra (PBG and zirconia), instead it shows additional absorptions at 1,550cm ^"1 and 620cm ^"1 attributed to bond formation between organic and inorganic phases.

Example 9: Hybrid polybutyleneglutarate (PBGVZirconia

0.5g (l.Og; 1.5g) of commercial polybutyleneglutarate di-hydroxy-terminated (PBG) (Aldrich, N° Catalogue: 445991, M _n 1,000 Da) are dissolved in 6ml of THF at room temperature, then 92μl (61μl; 30μl) of HCl (37%wt water solution, Fluka) are added (solution 10).

Separately 2.15g (1.43g; 0.72g) of a commercial solution of zirconium tetrapropoxide in 1- propanol (70% w/w solution) are weighed (solution 11). Solution 10 is slowly added to solution 11 under vigorous stirring. The obtained mixture 10+11 is stirred for 2min.

Mixture 10+11 is poured into a PTFE coated container and kept at room temperature for 24h. The obtained material is heat treated in an oven at 110 ⁰ C for 2h, yielding the hybrid sample.

The hybrid FT-IR spectrum shows all absorption bands of plain PBG, as well as absorptions typical of amorphous zirconia vibrations are observed. However, hybrid spectrum is not the mere addition of the two plain component spectra (PBG and zirconia), showing additional ab-

sorptions at 1,550cm ^"1 and 620cm ^"1 attributed to bond formation between organic and inorganic phases.

Example 10: Fabric treated with a hybrid coating.

Mixture 10+11, already described in Example 9, was applied to cotton fabric. Application was achieved by dipping cotton samples to be coated in mixture 10+11 for 15sec. Coated cotton samples were kept at room temperature for 24h and finally heat treated at 110 ⁰ C for Ih. At the end of the described procedure fabric samples with a hybrid coating were obtained and they were labeled as Cot-El 0-a, Cot-El 0-b, Cot-El 0-c.

Samples Cot-El 0-a, Cot-El 0-b, Cot-El 0-c were analyzed by TGA. The obtained results are listed in Table 4.

Table 4

Thermogravimetric results of cotton fabric samples coated with hybrid (Cot-E3-a, Cot-E3-b,

Cot-E3-c).

Sample Mixture 10+11 Hybrid load on Solid residue at Calculated

PBG/TPOZ fabric ¹ 600°C ^b residue

(%) (%) (%) (zirconia) ⁰

(%)

Cot-El 0-a 25/75 23.70 14.11 13.39

Cot-El 0-b 50/50 27.24 10.55 9.42

Cot-El 0-c 75/25 34.18 4.61 5.49

¹ Gravimetrically determined. b Residue obtained from TGA measurements run in air from room temperature to 600 ⁰ C at heating rate 20°/min.

^c Residue calculated according to the feed composition of mixture 10+11 and on the hybrid load on the cotton fabric.

As already discussed in Example 2 for hybrids Cot-E2-a, Cot-E2-b, Cot-E2-c, for samples Cot-El 0-a, Cot-El 0-b, Cot-El 0-c the solid residue obtained in air after heating at 600 ⁰ C is related to the zirconia content in the analyzed sample. The measured value is in all cases in good agreement with the calculated data (that takes into account both the mixture 10+11 composition and the hybrid load on the cotton fabric). This result demonstrates that, upon

deposition on the fabric, hybrid composition stays unchanged. Consequently composition of the hybrid coated on cotton fibres can be controlled by formulation of the mixture 10+11.

Comparison of SEM pictures of untreated cotton fabric and of the same fabric after coating with the hybrid show that the fibres composing the yarns are practically individually coated. Hence the coating does not macroscopically and indistinctly include the whole yarn, thus obstructing fabric porosity; on the contrary the fabric maintains the openings between yarns providing breathability and comfort.

Analogous results are obtained upon coating with the hybrid silk, wool and polyester fabrics.

Example 11 : Hybrid Poly(DX)lactide (P(DX)LA /Titania

0.5g (1.Og; 1.5g) of commercial poly(D,L) lactide (P(D ₅ L)LA) (Boehringer Ingelheim, Re- somer R 203 H) are dissolved in 6ml of chloroform at room temperature (solution 12).

Separately 1.5g (1.Og; 0.5g) of titanium tetraisopropoxide (TIPT) are mixed with 1.0ml of chloroform under vigorous stirring for 2min, obtaining solution 13. Solution 12 is slowly added to solution 13 under vigorous stirring obtaining mixture 12+13.

Mixture 12+13 is poured into a PTFE coated container and kept at room temperature for 24h. The obtained material is heat treated in an oven at 110 ⁰ C for 2h, yielding the hybrid sample.

The hybrid FT-IR spectrum shows all absorption bands of plain P(D ₅ L)LA, as well as absorptions typical of amorphous titania vibrations are observed. Although the starting polymer does not bear hydroxyl moieties at both chain ends as in Examples 1 to 9, FT-IR spectrum is still not the mere addition of the two plain component spectra (P(D ₅ L)LA and titania), showing additional absorptions at 1,580 cm ^"1 and 620cm ^"1 attributed to bond formation between organic and inorganic phases.

Example 12: Hybrid Polycapro lactone (PCLVTitania

By following the synthetic procedure of Example 10, except for the preparation of solution 12, hybrids PCL/Titania are prepared. Hybrid samples are labeled as E12-a, E12-b, E12-c, according to solution 12 composition.

Preparation of solution 12: 0,5g (l,0g; l,5g) of commercial polycaprolactone (PCL, Union Carbide, TONE P787 POLYMER) are dissolved in 6ml of chloroform at room temperature (solution 12).

In Figure 5 FT-IR spectra of hybrid E12-b and of the plain PBG polymer are compared. The hybrid spectrum shows all absorption bands of plain PCL, as well as absorptions typical of amorphous titania vibrations are observed. Although the starting polymer does not bear hy- droxyl moieties at both chain ends as in Examples 1 to 9, FT-IR spectrum is still not the mere addition of the two plain component spectra (PCL and titania), showing additional absorptions at 1540cm ^"1 and 615cm ^"1 (arrows in figure 5) attributed to bond formation between organic and inorganic phases.

Example 13: Hybrid Polycapro lactone (PCLVZirconia

0.5g (1.Og; 1.5g) of commercial polycaprolactone (PCL) are dissolved in 6ml of chloroform at room temperature (solution 15) .

Separately 2.15g (1.43g; 0.72g) of a commercial solution of zirconium tetrapropoxide in 1- propanol (70% w/w solution) are weighed (solution 16). Solution 15 is slowly added to solution 16 under vigorous stirring. The obtained mixture 15+16 is stirred for 2min.

Mixture 15+16 is poured into a PTFE-coated container and kept at room temperature for 24h. The obtained material is heat treated in an oven at 110 ⁰ C for 2h, yielding the hybrid sample.

The hybrid FT-IR spectrum shows all absorption bands of plain PCL, as well as absorptions typical of amorphous zirconia vibrations are observed. Although the starting polymer does not bear hydroxyl moieties at both chain ends as in Examples 1 to 9, FT-IR spectrum is still not the mere addition of the two plain component spectra (PCL and titania), showing additional absorptions at 1,550cm ^"1 and 630cm ^"1 attributed to bond formation between organic and inorganic phases.