CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

[0001] This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application Ser. No. 63/424,394, filed November 10, 2022, the entire contents of which is incorporated herein by reference.

FIELD

[0002] The present disclosure generally relates to functionalized coatings for inert substrates, which impart desirable chemical, physical and/or biological properties to the substrate. The present disclosure further generally relates to methods for coating inert substrates having multifarious geometric configurations.

BACKGROUND

[0003] Recent advances in the fields of proteomics and genomics have necessitated the development of high-throughput screening methods (HTS), such as microfluidic systems, for the systematic transformation of large amounts of biological/chemical data into organized databases. Microfluidic systems offer high analytical throughput and exhibit superior sensitivity and functionality compared to traditional micro-array techniques. Chip-based microfluidic operations, including cell-based assays, gene sequencing, immunoassays, electrophoresis, polymerase chain reaction, nucleic acid array technologies, and expression cloning, have substantially evolved over the past decade. Microfluidic platforms integrate efficient analytical technologies and sensitive detection methods, which may be used in various applications.

[0004] A microfluidic system may be integrated in a chip. The chip may be used to process a biological sample. Fluid transport in microfluidic devices is accomplished through fluid transport features formed in or on material layers, in the form of topological substrate features such as, for example, channels, troughs, and apertures, which provide fluid-wise transport and/or fluid-wise communication between various features of the device by allowing the passage of fluid. The chip may further comprise a plurality of compartments, which may be in communication with each other via the network of channels. The multidimensional topography and the micro scale of the microfluidic chip makes it a challenging substrate to manufacture and to modify.

[00051 A myriad of substrates or supports are available for microfluidic applications. Specific physical and chemical characteristics such as porosity, surface area, permeability, solvent resistance, hydrophilicity, flexibility and mechanical integrity need to be considered when selecting a substrate, although other characteristics, such as surface functionalization, may be important for certain applications. Well-established polymer mass fabrication techniques, such as injection molding, can be used manufacture micro devices, but the high cost, wasteful nature, and slow processing of such commonly used fabrication techniques, particularly for complex multi-layer geometries, severely impede the development process. Further, while low activity surfaces such as plastics can be derivatized to build in functionality through methods such as chemical vapor deposition, spray coating, spin coating and dip coating, these application methods can be difficult to use with substrates having confined or complex spatial geometries such as microfluidic chips.

[0006] As mentioned above, material integration and surface modification need to be tailored to the specifics of microfluidic systems, but often face prohibitive cost consideration and processing challenges. As such, there remains a need in the field for economic materials and methods for manufacturing substrates for microfluidic application, with streamlined processing for surface modification, integration of functional elements, and for making active channels.

SUMMARY OF THE INVENTION

[0007] The present disclosure provides methods for modifying and functionalizing inert substrates by installing reactive chemical groups on surfaces of inert substrates that can be used to derivatize and functionalize the surface with subsequent chemistries.

[0008] In some aspects, a method of modifying a surface of a substrate comprises (a) providing at least one substrate having at least one surface; (b) applying a first mixture comprising one or more silicon-based compound to at least a portion of the surface so as to at least partially coat the surface of the substrate to provide a first coated substrate; (c) curing the first coated substrate in an oxidizing atmosphere at a suitable temperature; (d) optionally applying a second coating mixture to at least a portion of the first cured coated substrate, the second coating mixture comprising one or more functionalization compound to provide a second coated substrate; and (e) optionally curing the said second coated substrate to provide a modified coated substrate.

[0009] In some embodiments of the method, the first coating mixture comprises the one or more silicon-based compound, a solvent and optionally a crosslinking catalyst. In other embodiments, the one or more silicon-based compound is a perhydropolysilazane or a perhydropoly siloxane. In some embodiments of the method, the solvent is selected from the group consisting of aromatic hydrocarbons, alkanes, ketones, alcohols, esters, ethers, and partially or completely fluorinated alkanes, ethers, ketones, amines, and ionic liquids, and wherein the solvent is present in an amount sufficient to dissolve the silicon-based compound. In some embodiments, the crosslinking catalyst is a base catalyst selected from the group consisting of sodium hydroxide, potassium hydroxide, potassium carbonate, diisopropylethylamine, triethylamine, N-methylmorpholine, pyridine, 4-(dimethylamino) pyridine, picoline, or a combination of any two or more thereof. In some embodiments, the oxidizing atmosphere is selected from the group consisting of air, oxygen, oxygen plasma, ozone, water vapor, ammonia, amines or a combination of any two or more thereof. In some embodiments, the first coated substrate is cured by heating it to a temperature between about 20° and about 200° C. In some embodiments, the first coated substrate is heated to a temperature in the range of about 30° to about 90° C for a time of about 15 min to about 24 h.

(0010] Disclosed herein are methods wherein the curing step is performed by one or more methods selected from the group consisting of chemical vapor deposition, spray coating, spin coating, dip coating, flow coating, passive wash coating, physical vapor deposition (PVD), chemical vapor deposition (CVD), sputtering, electron-beam deposition, electroplating, electrochemical deposition, gas-phase deposition, roll-to-roll deposition, screen printing, wet coating, dynamic coating, or a combination of any two or more thereof. [00111 In other aspects, a substrate coated with a functionalized silicon-based material is provided, wherein said functionalized silicon-based material comprises structural units having Formula I A or IB:

R ¹

R - S Ii - Y

R I ² (IB) wherein

X is selected from O, NR ^a , and CR ⁴ R ⁵ ;

Y is selected from H, Cl and OR ^b ; n is greater than 1; and each of R ¹ , R ² , and R ³ is independently a hydrogen, hydroxy, amino, a mono- or difunctional fluorinated group, substituted or unsubstituted Ci-6 alkyl, substituted or unsubstituted Ci-e haloalkyl, substituted or unsubstituted Ci-6 alkenyl, substituted or unsubstituted Ci-6 alkoxy, substituted or unsubstituted C3-C6 cycloalkyl, substituted or unsubstituted C5-C10 aryl, or substituted or unsubstituted 5- to 10-membered heteroaryl group; and each of R ⁴ , R ⁵ , R ^a and R ^b is independently a hydrogen, substituted or unsubstituted Ci- 6 alkyl, substituted or unsubstituted C3-C6 cycloalkyl, substituted or unsubstituted C5-C10 aryl, and substituted or unsubstituted 5- to 10-membered heteroaryl, or substituted or unsubstituted 3- to 10- membered heterocyclyl group.

10012] In some embodiments of structural units having Formula IA, X is O or NR ^a ; and R ¹ and R ² are each independently selected from a hydrogen, a mono- or di-functional fluorinated group, a substituted or unsubstituted C1-6 alkyl group, a substituted or unsubstituted C1-6 alkyl haloalkyl group and a substituted or unsubstituted C1-6 alkyl alkoxy group. In some embodiments, X is NR ^a ; and R ¹ and R ² and R ^a are all hydrogen. [0013] In some embodiments of structural units having Formula IB, Y is Cl or OR ^b ; and R ¹ , R ² and R ³ , are each independently selected from a hydrogen, a substituted or unsubstituted Ci-6 alkyl group, a substituted or unsubstituted Ci-6 haloalkyl group, and a substituted or unsubstituted Ci-6 alkoxy group.

[0014] In some embodiments, the one or more functionalization compound comprises a fluorinated compound having at least one functional group that is capable of reacting with said silicon-based compound. In other embodiments, the fluorinated compound is selected from the group consisting of hexafluoropropyleneoxide (HFPO) disilane, HFPO ether silane, perfluoropolyether (PFPE) disilane, PFPE amido silane, ethoxy functional polydimethylsiloxane, N-methylperfhiorobutanesulfonamidopropyltrimethoxysilane, perfluorooctyltriethoxysilane, or a combination of any two or more thereof.

[0015] In some embodiments, the substrate is selected from polymer, paper, glass, quartz, metal, textile, ceramic, acrylic and combinations of two or more thereof. In other embodiments, the substrate is a polymer selected from the group consisting of a thermoplastic polymer, a thermosetting polymer, or a combination thereof. In yet other embodiments, the polymer is selected from the group consisting of polyolefines, polyethers, polyesters, polyamides, polyimides, polyvinylchlorides, polyacrylates, fluoropolymers, and derivatives and copolymers thereof. In certain embodiments, the polymer is selected from the group consisting of polystyrene (PS), polycarbonate (PC), polytetrafluoroethylene (PTFE), Polyvinylidene fluoride (PVDF), Ethylene tetrafluoroethylene (ETFE), acrylonitrile butadiene styrene (ABS), polyethylene (PE), polypropylene (PP), polyvinyl- chloride (PVC), polyamide (PA), polyoxymethylene (POM), polyurethane (PU), polyimide (PI), polyether- ether-ketone (PEEK), polylactic acid (PLA), polymethylpentene (PMP), polymethacrylate, polymethyl methacrylate (PMMA), polyvinyl chloride, polyurethane-methacrylate (PUMA), polyethylene terephthalate (PET), polyglycolic acid (PGA), polyphosphazene, poly dimethyl siloxane (PDMS), unmodified or plasma-modified cyclic olefin copolymer (COC), nylon, or a combination of any two or more thereof. In some embodiments, the substrate is clear, translucent, textured, opaque, soft, hard, smooth, rough, flexible, rigid, patterned, primed, pre-treated, sacrificial, or a combination of any two or more thereof. In some embodiments, the substrate is a microfluidic substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[00161 The following drawings illustrate certain embodiments of the features and advantages of this disclosure. These embodiments are not intended to limit the scope of the appended claims in any manner. Like reference symbols in the drawings indicate like elements.

100.17] FIG. 1A shows the flowchart for a standard coating process of a substrate. FIG. IB shows the flowchart of an illustrative embodiment of the inventive coating process wherein the substrate is first coated with a coating including a silicon-based compound, followed by a second coating including mono- or multi-functional agent.

[0018] FIG. 2A shows a light microscopy image or micrograph of the microfluidic channel on a substrate prepared according to an illustrative embodiment of the inventive methods. FIG. 2B shows a comparative light microscopy image or micrograph of the microfluidic channel on a substrate prepared without the perhydropolysilazane coating.

[0019] FIG. 3A illustrates a substrate panel for a substrate prepared according to an illustrative embodiment of the inventive methods. FIG. 3B illustrates a comparative substrate panel for a substrate prepared without the perhydropolysilazane coating.

DETAILED DESCRIPTION

[0020] As used in the present disclosure and claims, the singular forms "a," "an," and "the" include plural forms unless the context clearly dictates otherwise.

[0021] It is understood that wherever aspects are described herein with the language "comprising," otherwise analogous aspects described in terms of "consisting of' and/or "consisting essentially of' are also provided. In this disclosure, "comprises," "comprising," "containing" and "having" and the like can mean "includes," "including," and the like;

"consisting essentially of' or "consists essentially of' are open-ended, allowing for the presence of more than that which is recited so long as basic or novel characteristics of that which is recited is not changed by the presence of more than that which is recited, but excludes prior art aspects. [0022] Unless specifically stated or obvious from context, as used herein, the term "or" is understood to be inclusive. The term "and/or" as used in a phrase such as "A and/or B" herein is intended to include both "A and B," "A or B," "A," and "B." Likewise, the term "and/or" as used in a phrase such as "A, B, and/or C" is intended to encompass each of the following aspects: A, B, and C; A, B, or C; A or C; A or B; B or C; A and C; A and B; B and C; A (alone); B (alone); and C (alone).

[0023] As used herein, the terms "about" and "approximately," when used to modify a numeric value or numeric range, indicate that deviations of up to 10% above and down to 10% below the value or range remain within the intended meaning of the recited value or range. It is understood that wherever aspects are described herein with the language "about" or "approximately" a numeric value or range, otherwise analogous aspects referring to the specific numeric value or range are also provided.

[0024] “Cx-y” when placed before a group refers to the number of carbon atoms in that group to be in the range of and including x and y. For example, a “Ci-6 alkyl” would refer to any alkyl group containing one to six carbon atoms.

[0025] The term “alkyl” refers to a monovalent, saturated aliphatic hydrocarbon radical having from 1 to 20 carbon atoms, and typically from 1 to 12 carbon atoms, and, in some embodiments, from 1 to 8 carbon atoms or from 1 to 6 carbon atoms. Higher carbon atom containing alkyl groups are also contemplated in certain embodiments, as the context will indicate. Alkyl may be a straight chain (i.e., linear) or a branched chain. Representative examples lower alkyl radicals include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, isopropyl, isobutyl, isopentyl, amyl, sec-butyl, tert-butyl, tert-pentyl, n-heptyl, n-octyl, and the like, along with branched variations thereof. The radical may be optionally substituted with substituents at positions that do not significantly interfere with the preparation of compounds falling within the scope of this invention and that do not significantly reduce the efficacy of the compounds. “Substituted alkyl” refers to an alkyl group having from 1 to 5, preferably 1 to 3, or more preferably 1 to 2 substituents independently selected from the group consisting of halo, lower alkoxy, hydroxy, cyano, nitro, or amino. As used herein the term haloalkyl is an alkyl group having one or more halo groups. In some embodiments, haloalkyl refers to a per-haloalkyl group. [0026] The term “alkenyl” straight chain, branched or cyclic alkyl groups having 2 to about 20 carbon atoms, and further including at least one double bond. In some embodiments, alkenyl groups have from 1 to 12 carbon atoms, from 1 to 8 carbon atoms, or, from 1 to 6 carbon atoms. Alkenyl groups may be substituted or unsubstituted. Alkenyl groups include, for instance, vinyl, propenyl, 2-butenyl, 3-butenyl, isobutenyl, cyclohexenyl, cyclopentenyl, cyclohexadienyl, butadienyl, pentadienyl, and hexadienyl groups among others. Alkenyl groups may be substituted similarly to alkyl groups. Divalent alkenyl groups, i.e., alkenyl groups with two points of attachment, include, but are not limited to, CH-CH=CH ₂ , C=CH ₂ , or C=CHCH ₃ .

[0027] The term “alkoxy” refers to a monovalent radical of the formula RO, where R is an alkyl as defined herein. Lower alkoxy refers to an alkoxy of 1-6 carbon atoms, with higher alkoxy is an alkoxy of seven or more carbon atoms. Representative lower alkoxy radicals include methoxy, ethoxy, n-propoxy, n-butoxy, n-pentyloxy, n-hexyloxy, isopropoxy, isobutoxy, isopentyloxy, amyloxy, sec-butoxy, tert-butoxy, tert-pentyloxy, and the like. Higher alkoxy radicals include those corresponding to the higher alkyl radicals set forth herein. The radical may be optionally substituted with substituents at positions that do not significantly interfere with the preparation of compounds falling within the scope of this invention and that do not significantly reduce the efficacy of the compounds. “Substituted alkoxy” refers to the group -©-(substituted alkyl) wherein substituted alkyl is defined herein.

[0028] The term “cycloalkyl” refers to a monovalent, alicyclic, saturated hydrocarbon radical having three or more carbons forming the ring. While known cycloalkyl compounds may have up to 30 or more carbon atoms, generally the cycloalkyl group has 3 to 8 ring members, whereas in other embodiments the number of ring carbon atoms range from 3 to 5, 6, or 7. Examples include, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl groups. The cycloalkyl groups may be optionally substituted with substituents at positions that do not significantly interfere with the preparation of compounds falling within the scope of this invention and that do not significantly reduce the efficacy of the compounds. “Substituted cycloalkyl” refers to a cycloalkyl group having from one to five substituents independently selected from the group consisting of halo, lower alkyl, lower alkoxy, hydroxy, cyano, nitro, amino, halogenated lower alkyl, halogenated lower alkoxy, hydroxycarbonyl, lower alkoxycarbonyl, lower alkylcarbonyloxy, and lower alkylcarbonylamino.

[0029] “Amino” refers to the group NH2.

[0030] "Aryl" or "Ar" refers to a monovalent aromatic carbocyclic group of from 6 to 14 carbon atoms having a single ring (e.g., phenyl (Ph)) or multiple condensed rings (e.g., naphthyl or anthryl) which condensed rings may or may not be aromatic (e.g., 2 benzoxazolinone, 2H 1,4 benzoxazin 3(4H) one 7 yl, and the like) provided that the point of attachment is at an aromatic carbon atom. Preferred aryl groups include phenyl and naphthyl. “Substituted aryl” refers to aryl groups which are substituted with 1 to 5, preferably 1 to 3, or more preferably 1 to 2 substituents selected from the group consisting of alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, alkoxy, substituted alkoxy, acyl, acylamino, acyloxy, amino, substituted amino, aminocarbonyl, aminothiocarbonyl, aminocarbonylamino, aminothiocarbonylamino, aminocarbonyloxy, aminosulfonyl, aminosulfonyloxy, aminosulfonylamino, amidino, aryl, substituted aryl, aryloxy, substituted aryloxy, arylthio, substituted arylthio, carboxyl, carboxyl ester, (carboxyl ester)amino, (carboxyl ester)oxy, cyano, cycloalkyl, substituted cycloalkyl, cycloalkyloxy, substituted cycloalkyloxy, cycloalkylthio, substituted cycloalkylthio, guanidino, substituted guanidino, halo, hydroxy, heteroaryl, substituted heteroaryl, heteroaryloxy, substituted heteroaryloxy, heteroarylthio, substituted heteroarylthio, heterocyclic, substituted heterocyclic, heterocyclyloxy, substituted heterocyclyloxy, heterocyclylthio, substituted heterocyclylthio, nitro, SO3H, substituted sulfonyl, sulfonyloxy, thioacyl, thiol, alkylthio, and substituted alkylthio, wherein said substituents are defined herein.

[0031 ] A “halo” substituent is a monovalent halogen radical chosen from chloro, bromo, iodo, and fluoro. A “halogenated” compound is one substituted with one or more halo substituent.

[0032] "Heteroaryl" refers to an aromatic group of from 1 to 10 carbon atoms and 1 to 4 heteroatoms selected from the group consisting of oxygen, nitrogen and sulfur within the ring. Such heteroaryl groups can have a single ring (e.g., pyridinyl or furyl) or multiple condensed rings (e.g., indolizinyl or benzothienyl) wherein the condensed rings may or may not be aromatic and/or contain a heteroatom provided that the point of attachment is through an atom of the aromatic heteroaryl group. In one embodiment, the nitrogen and/or the sulfur ring atom(s) of the heteroaryl group are optionally oxidized to provide for the N oxide (N— >0), sulfinyl, or sulfonyl moieties. Preferred heteroaryls include 5 or 6 membered heteroaryls such as pyridinyl, pyrrolyl, indolyl, thiophenyl, and furanyl. "Substituted heteroaryl" refers to heteroaryl groups that are substituted with from 1 to 5, preferably 1 to 3, or more preferably 1 to 2 substituents selected from the group consisting of the same group of substituents defined for substituted aryl.

[0033] Heterocycle" or "heterocyclic" or “heterocycloalkyl” or “heterocyclyl” refers to a saturated or partially saturated, but not aromatic, group having from 1 to 10 ring carbon atoms and from 1 to 4 ring heteroatoms selected from the group consisting of nitrogen, sulfur, or oxygen. Cx cycloalkyl refers to a heterocycloalkyl group having x number of ring atoms including the ring heteroatoms. Heterocycle encompasses single ring or multiple condensed rings, including fused bridged and spiro ring systems. In fused ring systems, one or more the rings can be cycloalkyl, aryl or heteroaryl provided that the point of attachment is through the non-aromatic ring. In one embodiment, the nitrogen and/or sulfur atom(s) of the heterocyclic group are optionally oxidized to provide for the N oxide, sulfinyl, sulfonyl moieties.

"Substituted heterocyclic" or “substituted heterocycloalkyl” or “substituted heterocyclyl” refers to heterocyclyl groups that are substituted with from 1 to 5 or preferably 1 to 3 of the same substituents as defined for substituted cycloalkyl.

[0034] It is understood that the above definitions are not intended to include impermissible substitution patterns (e.g., methyl substituted with 5 fluoro groups). Such impermissible substitution patterns are well known to the skilled artisan.

[0035] The ability to functionalize substrates with different materials in precise spatial locations would be a major advantage for a range of applications including microfluidic technologies. In some cases, this would involve incorporating functional materials directly within the channels that can partake in, guide or facilitate reactions in precisely controlled microenvironments. However, the integration of functional materials constitutes a major cost factor and presents challenges, especially in creating uniform surfaces for chemical modification of difficult to use substrate materials such as plastics and substrates having confined or complex geometries. The inventors have discovered that such substrates, e.g., microfluidic substrates, can be uniformly coated and their properties can be substantially modified by coating the substrate with a composition comprising a silicon-based compound and optionally a functionalization compound. A flowchart showing the steps of a standard coating process is shown in Figure 1 A, and a flowchart showing the steps of the inventive process described herein is depicted in Figure IB. The standard process provides a coated substrate that has multiple layers thick, requires high crosslinking, and has few surface bound strands. Conversely, the inventive process provides a coated substrate that has high surface adhesion and high surface functionality.

[0036] In an aspect, the present disclosure provides coating compositions, substrates and methods to install reactive chemical groups on inert surfaces that can be used to derivatize and functionalize the surface with subsequent chemistries. The application of the composition to install reactive groups can be done in both exposed and confined geometries, as well as complex non-uniform surfaces.

[0037] In an aspect, the present technology provides a substrate coated with a silicon- based material. The silicon-based material may be functionalized and include structural units having Formula IA or IB: wherein

X is selected from O, NR ^a , and CR ⁴ R ⁵ ;

Y is selected from H, Cl and OR ^b ; n is greater than 1; each of R ¹ , R ² , and R ³ is independently a hydrogen, hydroxy, amino, a mono- or difunctional fluorinated group, substituted or unsubstituted Ci-6 alkyl, substituted or unsubstituted Ci-6 haloalkyl, substituted or unsubstituted Ci-6 alkenyl, substituted or unsubstituted Ci-6 alkoxy, substituted or unsubstituted C3-C6 cycloalkyl, substituted or unsubstituted C5-C10 aryl, or substituted or unsubstituted 5- to 10-membered heteroaryl group; and each of R ⁴ , R ⁵ , R ^a and R ^b is independently a hydrogen, substituted or unsubstituted Ci- 6 alkyl, substituted or unsubstituted C3-C6 cycloalkyl, substituted or unsubstituted C5-C10 aryl, and substituted or unsubstituted 5- to 10-membered heteroaryl, or substituted or unsubstituted 3- to 10- membered heterocyclyl group.

100381 In some embodiments, X is O or NR ^a ; and R ¹ and R ² are each independently selected from a hydrogen, a mono- or di-functional fluorinated group, a substituted or unsubstituted C1-6 alkyl group, a substituted or unsubstituted C1-6 alkyl haloalkyl group and a substituted or unsubstituted C1-6 alkyl alkoxy group. In some embodiments, X is O or NR ^a ; and R ¹ , R ² and R ^a are each independently selected from a hydrogen, a mono- or di-functional fluorinated group, a substituted or unsubstituted C1-6 alkyl group, a substituted or unsubstituted C1-6 alkyl haloalkyl group and a substituted or unsubstituted C1-6 alkyl alkoxy group.

[0039] In some embodiments, X is NR ^a , and R ¹ , R ² and R ^a are all hydrogen. In some embodiments, n is selected from 3 to 10,000. In some embodiments, n is selected from 3 to 6,000. In some embodiments, n is selected from 3 to 3,000.

10040] In some embodiments, Y is Cl or OR ^b , and R ¹ , R ² , and R ³ are each independently selected from a hydrogen, hydroxy, a substituted or unsubstituted C1-6 alkyl group, a substituted or unsubstituted C1-6 haloalkyl group, and a substituted or unsubstituted C1-6 alkoxy group.

[0041 ] In some embodiments, Y is OR ^b , and R ¹ , R ² and R ³ are each independently hydrogen, hydroxy or methyl group. In some embodiments, n is selected from 3 to 10,000. In some embodiments, n is selected from 3 to 6,000. In some embodiments, n is selected from 3 to 3,000. [0042] The substrate of the present technology is intended may be any substrate which may effectively coated with a silicon-based material. Suitable substrates include, without limitation, polymer, paper, glass, quartz, metal, textile, ceramic, acrylic and combinations of any two or more thereof. Embodiments of the present disclosure relate to microfluidic substrates and microfluidic chips for accumulating a biological entity. In some embodiments, the substrate is a microfluidic substrate. The substrate may be clear, translucent, textured, opaque, soft, hard, smooth, rough, flexible, rigid, patterned, primed, pre-treated, sacrificial, or a combination of any two or more thereof.

[0043] In some embodiments, the substrate may include a polymer selected from the group consisting of a thermoplastic polymer, a thermosetting polymer, or a combination thereof. Suitable polymers may include, without limitation, polyolefines, polyethers, polyesters, polyamides, polyimides, polyvinylchlorides, polyacrylates, fluoropolymers, and derivatives or copolymers thereof. Illustrative polymer substrate materials may include polystyrene (PS), polycarbonate (PC), polytetrafluoroethylene (PTFE), Polyvinylidene fluoride (PVDF), Ethylene tetrafluoroethylene (ETFE), acrylonitrile butadiene styrene (ABS), polyethylene (PE), polypropylene (PP), polyvinyl- chloride (PVC), polyamide (PA), polyoxymethylene (POM), polyurethane (PU), polyimide (PI), polyether-ether-ketone (PEEK), polylactic acid (PLA), polymethylpentene (PMP), polymethacrylate, polymethyl methacrylate (PMMA), polyvinyl chloride, polyurethane-methacrylate (PUMA), polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), polyglycolic acid (PGA), polyphosphazene, poly dimethyl siloxane (PDMS), unmodified or plasma-modified cyclic olefin copolymer (COC), nylon, or any combination of any two or more thereof.

[0044] In an aspect, the present technology provides methods for treating and/or modifying the substrate with a coating composition of the invention. The methods utilize a silicon-based material as described hereinabove, including, without limitation, alkoxysilicates, polysilazanes, polyhydrosilaxanes, hydrosilanes, chlorosilanes, and the like or combinations thereof. In some embodiments, the silicon-based material may include polysilazane polymer comprised of C, Si, O, F, N and H. The polymer is then reacted with water at elevated temperature to produce a thin layer of silica on the desired surface. The silica surface can directly contain functional groups bound to the silicon atom or the hydroxyl rich surface of the silica can be derivatized or functionalized with silane species containing different functional groups including, without limitation, alkenes, alkynes, amines, acids, epoxides, anhydrides and isocyanates. The substrates can be modified to include a wide variety of functional groups to advantageously affect changes in the substrates, such as contact angle modification, addition of fluorescent or other molecules, and conjugation of biomolecules (e.g., enzymes, oligos and antibodies) for biological applications.

[0045] In an aspect, the present technology provides methods for modifying a surface of a substrate, the method including (a) providing at least one substrate having at least one surface; (b) applying a first mixture comprising one or more silicon-based compound to at least a portion of the surface so as to at least partially coat the surface of the substrate to provide a first coated substrate, (c) curing the first coated substrate in an oxidizing atmosphere at a suitable temperature; (d) optionally applying a second coating mixture to at least a portion of the first cured coated substrate, the second coating mixture comprising one or more functionalization compound to provide a second coated substrate; and (e) optionally curing the said second coated substrate to provide a modified coated substrate.

[0046] The methods of the present technology include applying a first mixture comprising one or more silicon-based compound to at least a portion of the surface so as to at least partially coat the surface of the substrate to provide a first coated substrate. In some embodiments, the first mixture may include the one or more silicon-based compound, a solvent and optionally a crosslinking catalyst. Suitable silicon-based compounds may include, without limitation, polysilazane, polysiloxane, perhydropolysilazane perhydropolysiloxane, silsesquioxane, hydrogen silsesquioxane, and the like or combinations thereof. In some embodiments, the first mixture can directly comprise functionalization compound. In such embodiments, the silicon-based compound (e.g., polysilazane) can be derivatized or functionalized before coating it on to the substrate. After coating, the substrate may be reacted with water at elevated temperature to produce a thin layer of silica on the substrate. During coating to the substrate, the substrate may be held at room temperature or at a slightly elevated temperature.

[0047] The first mixture may include a solvent that suitably dissolves the silicon- based compound while not affecting the substrate material. Suitable solvents include, without limitation, aromatic hydrocarbons, alkanes, ketones, alcohols, esters, ethers, partially or completely fluorinated alkanes, ethers, ketones, amines, and ionic liquids. The solvent is present in an amount sufficient to dissolve the silicon-based compound.

[0048] The first mixture may also include one or more optional additives. Such optional additives may include, for example, catalysts to assist with curing and/or crosslinking of silicon-based compounds in the first mixture once added to the solvent and coated on the substrate. In some embodiments, the crosslinking catalyst is a base catalyst. The base catalyst could be aqueous, organic, or fluorinated, and may include, without limitation, metal hydroxides (aqueous); primary/secondary/tertiary organic amines; alkoxides; amide salts (organic); and partially or completely fluorinated amines or alkoxide salts. Illustrative crosslinking catalysts may include sodium hydroxide, potassium hydroxide, potassium carbonate, diisopropylethylamine, triethylamine, N-methylmorpholine, pyridine, 4-(dimethylamino) pyridine, picoline, and the like, or combinations thereof. Some of the base catalysts, e.g., oxygen-containing bases such as sodium hydroxide, potassium hydroxide, and potassium carbonate may require coating immediately after mixing.

[0049] After coating the substrate with the first mixture, the first coated substrate thus obtained may be subjected to curing in an inert atmosphere or an oxidizing atmosphere at a suitable temperature. The oxidizing atmosphere may include applying or exposing the first coated substrate to a suitable oxidant including, without limitation, air, oxygen, oxygen plasma, ozone, water vapor, ammonia, amines and combinations of two or more thereof. The first coated substrate may be cured by heating it to a temperature between about 20° and about 200° C. In some embodiments, the curing may include heating the first coated substrate or its surface to a temperature of about 20°C to 200°C, about 25°C to 190°C, about 30°C to 180°C, about 35°C to 170°C, about 40°C to 160°C, about 45°C to 150°C, about 50°C to 140°C, about 55°C to 130°C, about 60°C to 120°C, about 70°C to 110°C, about 80°C to 100°C, about 85°C to 90°C, about 20° and about 150° C, about 20° and about 100° C, about 20° and about 80° C, about 30° and about 150° C, about 30° and about 90° C, about 30° and about 80° C, or any range including and/or in-between any two of these values. In some embodiments, the first coated substrate may be cured by heating it to a temperature between about 30° and about 90° C. In some embodiments, the curing may include heating the first coated substrate or its surface to a temperature of about 200°C, about 150°C, about 100°C, about 90°C, about 80°C, about 60°C, about 50°C, about 40°C, about 30°C, about 20°C, or any value thereinbetween.

[0050] Suitable curing time for the coating is in the range of about 5 min to about 30 h, such as about 10 min to about 28 h, about 15 min to about 24 h, about 30 min to about 20 h, about 45 min to about 15 h, about 1 h to about 10 h, about 1.5 h to about 5 h, about 2 h to about 4 h, or about 2.5 h to about 3 h, or any range including and/or in-between any two of these values. In certain embodiments, the curing may include heating the coated substrate or its surface to a suitable temperature for about 5 min, about 10 min, about 15 min, about 20 min, about 25 min, about 30 min, about 45 min, about 1 h, about 2 h, about 3 h, about 4 h, about 5 h, about 6 h, about 7 h, about 8 h, about 9 h, about 10 h, , about 11 h, about 12 h, about 13 h, about 14 h, about 15 h, about 16 h, about 17 h, about 18 h, about 19 h, about 20 h, about 21 h, about 22 h, about 23 h, about 24 h, or any value thereinbetween.

(0051 ] The first coating formed on the substrate surface according to the present disclosure may be continuous or discontinuous. In certain embodiments, the first coating covers at least about 20%, at least about 25%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, or about 100% of the substrate surface, or any range including and/or inbetween any two of these values.

[0052] In certain embodiments, the one or more silicon-based compound comprises or consists of perhydropolysilazane and/or perhydropolysiloxane. Thus, in one aspect, the method according to the present disclosure comprises applying a composition comprising perhydropolysilazane, perhydropolysiloxane or a mixture thereof to the surface of the substrate, and curing the coated substrate surface. In certain embodiments, the process steps can be repeated for multiple layers of the first coating mixture.

[0053] After forming the first coated substrate, a second coating mixture may be optionally applied to at least a portion of the first cured coated substrate. The second coating mixture may be applied to functionalize or derivatize the coating to include one or more functional groups. Thus, the second coating mixture may include one or more functionalization compound. The functionalization compound may include, for example, a fluorinated compound or a non-fluorinated compound having at least one functional group that is capable of reacting with said silicon-based compound. Suitable functionalization compounds may include, without limitation, fluorinated compounds, alkenes, alkynes, amines, acids, epoxides, anhydrides, isocyanates, and the like or combinations thereof. Suitable fluorinated compounds may include, without limitation, fluorosilanes, fluoroalkylsilanes, perfluoropolyether alkoxy silanes, perfluoroalkyl alkoxy silanes, fluoroalkylsilane-(non-fluoroalkylsilane) copolymers, and mixtures of fluoroalkylsilanes. Illustrative, fluorinated compounds include hexafluoropropyleneoxide (HFPO) disilane, HFPO ether silane, perfluoropolyether (PFPE) disilane, PFPE amido silane, ethoxy functional polydimethylsiloxane, N-methyl perfluorobutanesulfonamidopropyltrimethoxysilane, perfluorooctyltriethoxysilane, and the like, or combinations thereof. In certain embodiments, the functionalization compound includes a fluorinated polymer. The fluorinated polymer may be mono-functionalized or a multi-functionalized. In certain embodiments, the functionalization compound includes a mono-functionalized fluorinated polymer, e.g., a fluorosilane polymer. Examples of mono-functionalized fluorinated polymers includes fluoropolymer solutions marketed by 3M Company under the trade designation NOVEC®, e.g., NOVEC® 2022.

10054] The second coating mixture may be dissolved in a suitable solvent to dissolve or disperse the functionalization compound prior to application, although the coating may be used without a solvent. Exemplary solvents may include, without limitation, organic solvents and inorganic solvents, including, without limitation, fluorinated solvents, alcohols, ketones, esters, ethers, hydrocarbons, and the like, or combinations thereof. For example, the fluorosilane polymer (fluorinated polymer) may be optionally introduced in a hydrofluoroether solvent. In certain embodiments, the second coating mixture does not include a solvent. Following application of the second coating mixture, the substrate may be subjected to a second curing step to provide a modified coated substrate. Suitable temperatures and times for the second curing step may be in the ranges described for the first curing step. [0055] The first and the second coatings may be applied to the substrate using suitable methods known in the art, including, without limitation, chemical vapor deposition (CVD), spray coating, spin coating, dip coating, flow coating, immersion coating, dip coating, brush coating, passive wash coating, thermal deposition (physical vapor deposition), sputtering, electron-beam deposition, electroplating, electrochemical deposition, gas-phase deposition, roll-to-roll deposition, screen printing, wet coating, dynamic coating, manually application, or a combination of two or more thereof.

[0056] The first coating can be generally applied at a thickness of about 5 nm to about 10 micrometers, about 10 nm to about 8 micrometers, about 20 nm to about 5 micrometers, about 50 nm to about 1 micrometers, and about 100 nm to about 500 nm, or a range between and including any two of the foregoing values; however, according to other exemplary embodiments, the first coating may be applied at other thicknesses greater than or less than the stated ranges. In certain embodiments, the thickness of the first coating may range from about 5 nm to about 500 nm. The second coating can be generally applied at a thickness of about 5 nm to about 15 nm, about 7 nm to about 12 nm, about 8 nm to about 15 nm, and about 10 nm to about 15 nm, about 5 nm to about 50 nm, or a range between and including any two of the foregoing values; however, according to other exemplary embodiments, the second coating may be applied at other thicknesses greater than or less than the stated ranges. In certain embodiments, the thickness of the second coating may range from about 5 nm to about 15 nm. The combined thickness of the first and the second coating may range from about 5 nm to about 10 micrometers, about 10 nm to about 8 micrometers, about 20 nm to about 5 micrometers, about 50 nm to about 1 micrometers, and about 100 nm to about 500 nm, or a range between and including any two of the foregoing values; however, according to other exemplary embodiments, the two coatings may be applied at other thicknesses greater than or less than the stated ranges. In certain embodiments, the combined thickness of the first and the second coating may range from about 5 nm to about 500nm.

[0057] In certain embodiments, the method according to the present disclosure may produce a hydrophobic substrate surface that exhibits a high water contact angle. The contact angle, refers to the angle at which a liquid/vapor interface meets a solid surface. In certain embodiments, the water contact angle of the substrate surface may be greater than at least about 100°. In certain embodiments, the contact angle may be greater than at least about 110°, greater than at least about 120°, greater than at least about 125°, greater than at least about 130°, greater than at least about 135°, greater than at least about 140°, greater than at least about 145°, greater than at least about 150°, greater than at least about 160°, greater than at least about 170°, greater than at least about 180°, or a range between and including any two of the foregoing values. For example, the contact angle may range from about 100° to about 180°, from about 110° to about 180°, or from about 120° to 145°. In certain embodiments, the contact angle may be greater than at least 100°, greater than at least 110°, greater than at least 120°, greater than at least 130°, greater than at least 140°, greater than at least 150°, greater than at least 160°, greater than at least 170°, greater than at least 180°, or a range between and including any two of the foregoing values.

[0058] The methods described herein can be used to modify the surface of substrates, such as chips, using functionalized coatings such as fluorinated silanes to produce an ultrahydrophobic surface inside the confined geometry of a chip. The method has a lot of advantages such as providing a uniform substrate surface, providing a functionalized and durable coating on the surface of a substrate, allowing for the fast manufacturer of parts with plastic injection molding while giving the functionality of glass parts to do surface functionalization with oligos and other biological materials inside difficult to reach surfaces of the substrates. The perhydropolysilazane or perhydropolysiloxane coating can be designed with a variety of functional groups to perform crosslinking chemistry driven by UV or free radical chemistry and provide substrates having improve durability, abrasion resistance and chemical resistance.

[0059] The following examples are given for the purpose of illustrating various embodiments of the disclosure and are not meant to limit the present disclosure in any fashion. One skilled in the art will appreciate readily that the present disclosure is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as those objects, ends and advantages inherent herein. The present examples, along with the methods described herein are presently representative of embodiments and are exemplary, and are not intended as limitations on the scope of the disclosure. Changes therein and other uses which are encompassed within the spirit of the disclosure as defined by the scope of the claims will occur to those skilled in the art. It is to be understood that this present technology is not limited to particular methods, reagents, compounds compositions or biological systems, which can, of course, vary. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

EXAMPLES

Example 1. Coating of Substrate

[0060] In the present example, a plasma-modified cyclic olefin copolymer (COC) substrate was subjected to a two-step coating process. The substrate was first coated with PHPS thin film, followed by a mono-functionalized fluorinated polymer using the following conditions:

Substrate: Plasma-modified cyclic olefin copolymer (COC);

Coating material: Perhydropolysilazane (PHPS) at 0.5 wt.% with 15uL and 20 uL wash; Catalyst: N,N-Diisopropylethylamine (DIPEA) at 0.2 wt.%;

Curing: Cure at 60 °C and 60% RH for 1 h;

Post-treatment: Coat with 0.2 wt.% fluorinated polymer (NOVEC® 2202; 3M Company) (mono-functionalized) with 20 uL and wash with 30 uL;

Post-treatment curing: Cure at 60 °C and 60% RH for 30 min.

Example 2: Light Microscopy

10061] The microfluidic channel for the coated substrates was observed using an imaging device such as a light microscope, which permits monitoring of the flow of beads along the microfluidic channel and whether the beads and an aqueous solution are capable of being formed into water-in-oil droplets at the exit of the microfluidic channel. The flow was observed for dual-coated substrate prepared according to Example 1 as well as a comparative substrate, which includes only the functionalized coating. Figure 2 A shows an light microscopy image or micrograph of the microfluidic channel on a substrate prepared according to an embodiment of the methods of the present disclosure, i.e., Example 1, which yields microfluidic channels that are capable of forming droplets (water-in-oil emulsions). In contrast, Figure 2B depicts light microscopy image or micrograph of a substrate which does not include the PHPS coating, but is directly treated with the functionalized coating (NOVEC® 2202), and which is not capable of reliably forming droplets.

|0062] The observations of the light microscopy can be illustrated in the form of a basic visual characterization of the channel surfaces. Figure 3 A illustrates a substrate panel with the PHPS coating and the mono-functional fluorosilane polymer (NOVEC® 2202) coating. It is evident that the PHPS coating (which likely forms a silica layer) effectively yields a new surface that can be broadly and uniformly functionalized with a mono-functional fluorosilane polymer, such as NOVEC® 2202. On the other hand, Figure 3B illustrates a substrate panel which excludes the PHPS coating, where in the absence of the creation of the new surface with PHPS, the uniformity of the fluorosilane polymer is spotty and non-uniform at best, and the benefit of functionalized coating is lost. In the absence of the PHPS coating, there is no surface modification (and poor to no droplet formation) due to poor adhesion of the fluorosilane polymer to the surface of the microfluidics channel.

(0063] The invention is not to be limited in scope by the specific aspects described herein. Indeed, various modifications of the invention in addition to those described will become apparent to those skilled in the art from the foregoing description and accompanying figures. Such modifications are intended to fall within the scope of the appended claims.

[0064] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, patent application, or item of information was specifically and individually indicated to be incorporated by reference. To the extent publications, patents, patent applications, and items of information incorporated by reference contradict the disclosure contained in the specification, the specification is intended to supersede and/or take precedence over any such contradictory material.

[0065] Where values are described in terms of ranges, it should be understood that the description includes the disclosure of all possible sub-ranges within such ranges, as well as specific numerical values that fall within such ranges irrespective of whether a specific numerical value or specific sub-range is expressly stated. [0066] The term “each,” when used in reference to a collection of items, is intended to identify an individual item in the collection but does not necessarily refer to every item in the collection, unless expressly stated otherwise, or unless the context of the usage clearly indicates otherwise.

10067] Various embodiments of the features of this disclosure are described herein. However, it should be understood that such embodiments are provided merely by way of example, and numerous variations, changes, and substitutions can occur to those skilled in the art without departing from the scope of this disclosure. It should also be understood that various alternatives to the specific embodiments described herein are also within the scope of this disclosure.

10068] Other aspects are within the following claims.