TECHNICAL FIELD

The present disclosure relates to optically transparent polyamideimides.

BACKGROUND ART

Organic films are high in flexibility as compared to glass, difficult to break, and lightweight. Recently, a study has been performed with the aim of developing a flexible display using organic film as the substrate of a flat panel display.

Generally, resins used in organic film include polyester, polyamide, polyimide, polyamideimide, polycarbonate, polyether sulfone, acrylic, and epoxy. Of these, polyamideimide resin is high in heat resistance, mechanical strength, abrasion resistance, dimensional stability, chemical resistance, insulation capability, and accordingly in wide use in the electric/electronic industries.

For use as an alternative to the glass substrate in display elements, polyamideimide resin should also have high transparency and low birefringence. These properties are necessary to obtain clear images. However, manufacturing methods provide inconsistencies in resins leading to variation in performance properties. Accordingly, there is a need for devising and improving processes that lead to performance consistency.

SUMMARY

Various aspects and embodiments contemplated herein may include, but are not limited to, one or more of the following.

In a first aspect, a polyamideimide includes a moiety selected from:

mbination thereof.

In a second aspect, an optical stack includes a polyamideimide according to the foregoing first aspect.

In a third aspect, an electronic device includes a polyamideimide according to the foregoing first aspect.

In a fourth aspect, a polyamideimide film includes a moiety selected from:

combination thereof.

In a fifth aspect, a method of forming a polyamideimide includes: polymerizing at least one dianhydride monomer and at least one diamine monomer to form the polyamideimide, wherein the polyamideimide includes at least one moiety selected from:

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

The following description in combination with the figures is provided to assist in understanding the teachings disclosed herein. The following discussion will focus on specific implementations and embodiments of the teachings. This focus is provided to assist in describing the teachings and should not be interpreted as a limitation on the scope or applicability of the teachings.

Definitions:

As used herein, the term “any suitable derivative” means any chemical compound capable of producing the same chemical reaction product as the compounds listed in the sentences with the term “any suitable derivative.” For example, and without limiting the scope of the present disclosure, if the sentence lists an acid chloride compound A as a comonomer for the formation of a polyamide-imide, any suitable derivatives are chemical compounds that yield the same polyamide-imide, such as the acid bromide, or an ester derivative of compound A.

As used herein, the term “about” means +/- 10% of any recited value. As used herein, this term modifies any recited value, range of values, or endpoints of one or more ranges.

As used herein, the terms “top,” “bottom,” “upper,” “lower,” “above,” and “below” are used to provide a relative relationship between structures. The use of these terms does not indicate or require that a particular structure must be located at a particular location in the apparatus.

As used herein, the terms “comprises”, “comprising”, “includes”, “including”, “has”, “having” or any other variation thereof, are open-ended terms and should be interpreted to mean “including, but not limited to. . . .” These terms encompass the more restrictive terms “consisting essentially of’ and “consisting of.” In an embodiment, a method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive-or and not to an exclusive-or. For example, a condition A or B is satisfied by any one of the following: A is true (or present), and B is false (or not present), A is false (or not present), and B is true (or present), and both A and B are true (or present).

It should be noted that ratios, concentrations, amounts, and other numerical data may be expressed herein in a range format. It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. To illustrate, a concentration range of “about 0.1% to about 5%” should be interpreted to include not only the explicitly recited concentration of about 0.1 wt. % to about 5 wt. %, but also include individual concentrations (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.5%, 1.1%, 2.2%, 3.3%, and 4.4%) within the indicated range. In an embodiment, the term “about” can include traditional rounding according to significant figures of the numerical value. In addition, the phrase “about ‘x’ to ‘y’” includes “about ‘x’ to about ‘y’”.

Also, the use of “a” or “an” is employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural, or vice versa, unless it is clear that it is meant otherwise. For example, when a single item is described herein, more than one item may be used in place of a single item. Similarly, where more than one item is described herein, a single item may be substituted for that more than one item.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The materials, methods, and examples are illustrative only and not intended to be limiting. To the extent not described herein, many details regarding specific materials and processing acts are conventional and may be found in reference books and other sources within the structural arts and corresponding manufacturing arts. Unless indicated otherwise, all measurements are at about 23°C +/- 5°C per ASTM, unless indicated otherwise.

As described above, a polyamideimide includes a moiety selected from:

5 mbination thereof.

In an embodiment, the polyamideimide is selected from the moiety consisting essentially of: combination thereof. In another embodiment, the polyamideimide is selected from the moiety consisting of: combination thereof. In one embodiment, the polyamideimide is formed into a film. The film has advantageous properties such as structural, thermal, mechanical, and optical properties. For instance, the film has at least two properties including, but not limited to:

(i) a thickness of not greater than 100 pm, not greater than 90 pm, not greater than 80 pm, not greater than 70 pm, not greater than 60 pm, not greater than 50 pm, not greater than 40 |im, not greater than 35 |im, not greater than 30 |im, or not greater than 25 pm;

(ii) a tensile modulus according to ASTM D638-14 of at least 3 GPa, at least 5.2 GPa, at least 5.4 GPa, at least 5.6 GPa, at least 5.8 GPa, at least 6 GPa, at least 6.2 GPa, at least 6.4 GPa, at least 6.6 GPa, at least 6.8 GPa, at least 7 GPa, at least 7.2 GPa, at least 7.4 GPa, at least 7.6 GPa, at least 7.8 GPa, at least 8 GPa, at least 8.2 GPa, at least 8.5 GPa, at least 9 GPa, or at least 10 GPa;

(iii) a first optical transparency according to ASTM D1746-15 at 380 nm of less than 50%, less than 40%, less than 35%, less than 30%, less than 25%, less than 20%, less than 15%, less than 10%, less than 8%, less than 6%, less than 4%, less than 2%, or less than 1%, and a second optical transparency according to ASTM D1746-15 at 400 nm of greater than 50%, greater than 60%, greater than 70%, greater than 80%, greater than 82%, greater than 84%, greater than 86%, greater than 88%, greater than 90%, greater than 92%, greater than 94%, greater than 96%, or greater than 98%;

(iv) a Yellowing Index according to ASTM E313-20 of not greater than 4.5, not greater than 2.4, not greater than 2.3, not greater than 2.2, not greater than 2.1, not greater than 2.0, not greater than 1.9, not greater than 1.8, not greater than 1.7, not greater than 1.6, not greater than 1.5, not greater than 1.4, or not greater than 1.3;

(v) a haze as determined according to ASTM D 1003- 13 of not greater than 1.5%, not greater than 1.3%, not greater than 1.1%, not greater than 1.0%, not greater than 0.8%, not greater than 0.6%, not greater than 0.5%, not greater than 0.4%, or not greater than 0.3%;

(vi) a pencil hardness of greater than HB, greater than 1H, greater than 2H, greater than 3H, greater than 4H, greater than 5H, or greater than 6H;

(vii) a coefficient of moisture expansion (‘CME’) as determined according to ASTM D5229/D5229M-14 of not greater than 50 ppm, not greater than 45 ppm, not greater than 40 ppm, not greater than 35 ppm, not greater than 30 ppm, not greater than 25 ppm, not greater than 20 ppm, or not greater than 15 ppm;

(viii) an elongation at break as determined according to ASTM D638-14 of at least 2%, at least 15%, at least 20%, at least 22%, at least 24%, at least 26%, at least 28%, at least 30%, at least 35%, or at least 40%; or

(ix) a folding endurance as determined according to ASTM D2176-16 at a radius of 1 mm of at least 10,000 folds, at least 20,000 folds, at least 50,000 folds, at least 80,000 folds, at least 100,000 folds, at least 150,000 folds, at least 180,000 folds, at least 200,000 folds, at least 250,000 folds, at least 300,000 folds, at least 500,000 folds, or at least 1,000,000 folds.

The polyamideimide film has at least two, at least three, or at least four properties selected from (i) through (ix). In an embodiment, the polyamideimide film has at least three properties selected from (i) through (ix), at least four properties selected from (i) through (ix), at least five properties selected from (i) through (ix), at least six properties selected from (i) through (ix), at least seven properties selected from (i) through (ix), at least eight properties selected from (i) through (ix), or all properties selected from (i) through (ix).

In one embodiment, the polyamideimide is formed with at least one moiety including a diamine reacted with at least one moiety including a dianhydride. Any reasonable diamine is envisioned. In an embodiment, the diamine is selected from: combination thereof.

In an embodiment, the diamine consists essentially of: diamine of formula (13) is also known as Nl,N4-bis[4-(2-aminoethyl)phenyl]benzene-l,4- dicarboxamide (APEA TPC 1). The diamine of formula (14) is also known as Nl,N4-bis[2-

(4-aminophenyl)ethyl]benzene-l,4-dicarboxamide (APEA TPC 2). In yet another embodiment, the diamine can be selected independently for each occasion from the group consisting of: combination thereof. In an embodiment, the polyamideimide is further formed with at least one moiety including at least one dianhydride. Any dianhydride is envisioned. In a particular embodiment, the dianhydride is selected from:

Moreover in one embodiment, the dianhydride is selected from the group consisting essentially of: , also known as “6FDA”.

In an embodiment, the dianhydride is selected from the group consisting of:

In one embodiment, the diamine moiety and the dianhydride moiety can be in any molar ratio. The molar ratio of the diamine moiety : dianhydride moiety can range from 10:1 to 1:10, from 5:1 to 1:5, from 3:1 to 1:3, from 2:1 to 1:2, from 3:2 to 2:3, from 4:3 to 3:4, from 5:4 to 4:5, from 6:5 to 5:6, from 7:6 to 6:7, from 8:7 to 7:8, from 9:8 to 8:9, or from 10:9 to 9:10. In one embodiment, the diamine moiety is in the majority. In another embodiment, the polyamideimide may include a third, a fourth, and further moieties. For such multiple monomeric systems, the molar ratio of first to the sum of all other monomers can range from 10:1 to 1: 10, from 5:1 to 1:5, from 3:1 to 1:3, from 2:1 to 1:2, from 3:2 to 2:3, from 4:3 to 3:4, from 5:4 to 4:5, from 6:5 to 5:6, from 7:6 to 6:7, from 8:7 to 7:8, from 9:8 to 8:9, or from 10:9 to 9:10.

In an embodiment, an optical stack can include a polyamideimide according to the first aspect or its embodiments. For example, the polyamideimide can form a rear or backing layer or a cover layer of the optical stack. In another embodiment, the polyamideimide can be a substrate to the nanocircuitry of an optical stack. In yet another embodiment, the polyamideimide can form the horizontal or vertical polarizer of an optical stack or the layers adjacent to the liquid crystal layers. In one further embodiment, the optical stack is an LED or an OLED assembly. The polyamideimide layer can be a substrate or cover layer of the LED or OLED assembly.

In an embodiment, an electronic device includes a polyamideimide according to the first aspect. The electronic device can include but is not limited to telephones, cell phones, personal computers, desktop computers, laptops, tablet computers, printers, flatscreen TVs, music players, digital cameras, camcorders, video game consoles, remote controls, smart appliances, automobile control displays, marine and aviation transport control systems.

In an embodiment, a method of forming a polyamideimide is provided. The method includes polymerizing at least one dianhydride monomer and at least one diamine monomer to form the polyamideimide. The polyamideimide formed includes at least one moiety selected from polyamideimide moiety described above. The at least one dianhydride monomer and at least one diamine monomer can be selected from the dianhydride monomer and diamine monomer described above. Many different aspects and embodiments are possible. Some of those aspects and embodiments are described herein. After reading this specification, skilled artisans will appreciate that those aspects and embodiments are only illustrative and do not limit the scope of the present invention. Embodiments may be in accordance with any one or more of the items as listed below.

Embodiment 1. A polyamideimide including a moiety selected from:

Embodiment 2. The polyamideimide in accordance with embodiment 1, wherein the polyamideimide is a film, the film including at least two properties selected from:

(i) a thickness of not greater than 100 pm, not greater than 90 pm, not greater than 80 pm, not greater than 70 pm, not greater than 60 pm, not greater than 50 pm, not greater than 40 pm, not greater than 35 pm, not greater than 30 pm, or not greater than 25 pm;

(ii) a tensile modulus according to ASTM D638-14 of at least 3 GPa, at least 5.2 GPa, at least 5.4 GPa, at least 5.6 GPa, at least 5.8 GPa, at least 6 GPa, at least 6.2 GPa, at least 6.4 GPa, at least 6.6 GPa, at least 6.8 GPa, at least 7 GPa, at least 7.2 GPa, at least 7.4 GPa, at least 7.6 GPa, at least 7.8 GPa, at least 8 GPa, at least 8.2 GPa, at least 8.5 GPa, at least 9 GPa, or at least 10 GPa;

(iii) a first optical transparency according to ASTM D1746-15 at 380 nm of less than 50%, less than 40%, less than 35%, less than 30%, less than 25%, less than 20%, less than 15%, less than 10%, less than 8%, less than 6%, less than 4%, less than 2%, or less than 1%, and a second optical transparency according to ASTM D1746-15 at 400 nm of greater than 50%, greater than 60%, greater than 70%, greater than 80%, greater than 82%, greater than 84%, greater than 86%, greater than 88%, greater than 90%, greater than 92%, greater than 94%, greater than 96%, or greater than 98%; (iv) a Yellowing Index according to ASTM E313-20 of not greater than 4.5, not greater than 2.4, not greater than 2.3, not greater than 2.2, not greater than 2.1, not greater than 2.0, not greater than 1.9, not greater than 1.8, not greater than 1.7, not greater than 1.6, not greater than 1.5, not greater than 1.4, or not greater than 1.3;

(v) a haze as determined according to ASTM D 1003- 13 of not greater than 1.5%, not greater than 1.3%, not greater than 1.1%, not greater than 1.0%, not greater than 0.8%, not greater than 0.6%, not greater than 0.5%, not greater than 0.4%, or not greater than 0.3%;

(vi) a pencil hardness of greater than HB, greater than 1H, greater than 2H, greater than 3H, greater than 4H, greater than 5H, or greater than 6H;

(vii) a coefficient of moisture expansion (‘CME’) as determined according to ASTM D5229/D5229M-14 of not greater than 50 ppm, not greater than 45 ppm, not greater than 40 ppm, not greater than 35 ppm, not greater than 30 ppm, not greater than 25 ppm, not greater than 20 ppm, or not greater than 15 ppm;

(viii) an elongation at break as determined according to ASTM D638-14 of at least 2%, at least 15%, at least 20%, at least 22%, at least 24%, at least 26%, at least 28%, at least 30%, at least 35%, or at least 40%; or

(ix) a folding endurance as determined according to ASTM D2176-16 at a radius of 1 mm of at least 10,000 folds, at least 20,000 folds, at least 50,000 folds, at least 80,000 folds, at least 100,000 folds, at least 150,000 folds, at least 180,000 folds, at least 200,000 folds, at least 250,000 folds, at least 300,000 folds, at least 500,000 folds, or at least 1,000,000 folds.

Embodiment 3. The polyamideimide in accordance with embodiment 2, including at least three properties selected from (i) through (ix), at least four properties selected from (i) through (ix), at least five properties selected from (i) through (ix), at least six properties selected from (i) through (ix), at least seven properties selected from (i) through (ix), at least eight properties selected from (i) through (ix), or all properties selected from (i) through (ix).

Embodiment 4. The polyamideimide in accordance with any of the preceding embodiments, formed with at least one moiety including at least one diamine.

Embodiment 5. The polyamideimide in accordance with embodiment 4, wherein the diamine is selected from the group consisting of:

Embodiment 6. The polyamideimide in accordance with any of the preceding embodiments, formed with at least one moiety including at least one dianhydride.

Embodiment 7. The polyamideimide in accordance with embodiment 6, wherein the dianhydride is selected from the group consisting of:

Embodiment 8. The polyamideimide in accordance with embodiment 7, wherein the dianhydride is selected from:

Embodiment 9. The polyamideimide in accordance with embodiments 4-8, wherein the diamine and the dianhydride are in a molar ratio ranging from 10:1 to 1:10, from 5:1 to 1:5, from 3:1 to 1:3, from 2:1 to 1:2, from 3:2 to 2:3, from 4:3 to 3:4, from 5:4 to 4:5, from

6:5 to 5:6, from 7:6 to 6:7, from 8:7 to 7:8, from 9:8 to 8:9, or from 10:9 to 9:10.

Embodiment 10. An optical stack including the polyamideimide according to embodiments 1 through 9.

Embodiment 11. An electronic device including the polyamideimide according to embodiments 1 through 9.

Embodiment 12. A polyamideimide film including a moiety selected from: combination thereof.

Embodiment 13. The polyamideimide film in accordance with embodiment 12, wherein the polyamideimide film includes at least two properties selected from:

(i) a thickness of not greater than 100 pm, not greater than 90 pm, not greater than 80 pm, not greater than 70 pm, not greater than 60 pm, not greater than 50 pm, not greater than 40 pm, not greater than 35 pm, not greater than 30 pm, or not greater than 25 pm;

(ii) a tensile modulus according to ASTM D638-14 of at least 3 GPa, at least 5.2 GPa, at least 5.4 GPa, at least 5.6 GPa, at least 5.8 GPa, at least 6 GPa, at least 6.2 GPa, at least 6.4 GPa, at least 6.6 GPa, at least 6.8 GPa, at least 7 GPa, at least 7.2 GPa, at least 7.4 GPa, at least 7.6 GPa, at least 7.8 GPa, at least 8 GPa, at least 8.2 GPa, at least 8.5 GPa, at least 9 GPa, or at least 10 GPa;

(iii) a first optical transparency according to ASTM D1746-15 at 380 nm of less than 50%, less than 40%, less than 35%, less than 30%, less than 25%, less than 20%, less than 15%, less than 10%, less than 8%, less than 6%, less than 4%, less than 2%, or less than 1%, and a second optical transparency according to ASTM D1746-15 at 400 nm of greater than 50%, greater than 60%, greater than 70%, greater than 80%, greater than 82%, greater than 84%, greater than 86%, greater than 88%, greater than 90%, greater than 92%, greater than 94%, greater than 96%, or greater than 98%;

(iv) a Yellowing Index according to ASTM E313-20 of not greater than 4.5, not greater than 2.4, not greater than 2.3, not greater than 2.2, not greater than 2.1, not greater than 2.0, not greater than 1.9, not greater than 1.8, not greater than 1.7, not greater than 1.6, not greater than 1.5, not greater than 1.4, or not greater than 1.3; (v) a haze as determined according to ASTM D 1003- 13 of not greater than 1.5%, not greater than 1.3%, not greater than 1.1%, not greater than 1.0%, not greater than 0.8%, not greater than 0.6%, not greater than 0.5%, not greater than 0.4%, or not greater than 0.3%;

(vi) a pencil hardness of greater than HB, greater than 1H, greater than 2H, greater than 3H, greater than 4H, greater than 5H, or greater than 6H;

(vii) a coefficient of moisture expansion (‘CME’) as determined according to ASTM D5229/D5229M-14 of not greater than 50 ppm, not greater than 45 ppm, not greater than 40 ppm, not greater than 35 ppm, not greater than 30 ppm, not greater than 25 ppm, not greater than 20 ppm, or not greater than 15 ppm;

(viii) an elongation at break as determined according to ASTM D638-14 of at least 2%, at least 15%, at least 20%, at least 22%, at least 24%, at least 26%, at least 28%, at least 30%, at least 35%, or at least 40%; or

(ix) a folding endurance as determined according to ASTM D2176-16 at a radius of 1 mm of at least 10,000 folds, at least 20,000 folds, at least 50,000 folds, at least 80,000 folds, at least 100,000 folds, at least 150,000 folds, at least 180,000 folds, at least 200,000 folds, at least 250,000 folds, at least 300,000 folds, at least 500,000 folds, or at least 1,000,000 folds.

Embodiment 14. The polyamideimide film in accordance with embodiment 13, including at least three properties selected from (i) through (ix), at least four properties selected from (i) through (ix), at least five properties selected from (i) through (ix), at least six properties selected from (i) through (ix), at least seven properties selected from (i) through (ix), at least eight properties selected from (i) through (ix), or all properties selected from (i) through (ix).

Embodiment 15. The polyamideimide film in accordance with embodiments 12-14, formed with at least one moiety including at least one diamine selected from the group combination thereof. Embodiment 16. The polyamideimide film in accordance with embodiments 12-15, formed with at least one dianhydride.

Embodiment 17. The polyamideimide film in accordance with embodiment 16, wherein the dianhydride is selected from the group consisting of:

Embodiment 18. The polyamideimide film in accordance with embodiment 17, wherein the dianhydride is selected from:

Embodiment 19. The polyamideimide film in accordance with embodiment 18, wherein the diamine and the dianhydride are in a molar ratio ranging from 10:1 to 1:10, from 5:1 to 1:5, from 3:1 to 1:3, from 2:1 to 1:2, from 3:2 to 2:3, from 4:3 to 3:4, from 5:4 to 4:5, from 6:5 to 5:6, from 7:6 to 6:7, from 8:7 to 7:8, from 9:8 to 8:9, or from 10:9 to 9:10.

Embodiment 20. The polyamideimide film in accordance with embodiments 12-19, wherein the moiety consists essentially of: combination thereof.

Embodiment 21. The polyamideimide film in accordance with embodiment 20, wherein the moiety consists of: combination thereof.

Embodiment 22. A method of forming a polyamideimide including: polymerizing at least one dianhydride monomer and at least one diamine monomer to form the polyamideimide, wherein the polyamideimide comprises at least one moiety selected from:

Embodiment 23. The method in accordance with embodiment 22, wherein the diamine is selected from the group consisting of: bination thereof.

Embodiment 24. The method in accordance with embodiment 22, wherein the dianhydride is selected from the group consisting of:

Embodiment 25. The method in accordance with embodiments 22-24, wherein the diamine and the dianhydride are in a molar ratio ranging from 10:1 to 1:10, from 5:1 to 1:5, from 3:1 to 1:3, from 2:1 to 1:2, from 3:2 to 2:3, from 4:3 to 3:4, from 5:4 to 4:5, from 6:5 to 5:6, from 7:6 to 6:7, from 8:7 to 7:8, from 9:8 to 8:9, or from 10:9 to 9:10.

Embodiment 26. The method in accordance with embodiments 22-25, wherein the polyamideimide is formed into a film.

Embodiment 27. The method in accordance with embodiment 26, wherein the film has a tensile modulus according to ASTM D638-14of at least 3 GPa, at least 5.2 GPa, at least 5.4 GPa, at least 5.6 GPa, at least 5.8 GPa, at least 6 GPa, at least 6.2 GPa, at least 6.4 GPa, at least 6.6 GPa, at least 6.8 GPa, at least 7 GPa, at least 7.2 GPa, at least 7.4 GPa, at least 7.6 GPa, at least 7.8 GPa, at least 8 GPa, at least 8.2 GPa, at least 8.5 GPa, at least 9 GPa, or at least 10 GPa.

The following examples are provided to better disclose and teach processes and compositions of the present invention. They are for illustrative purposes only, and it must be acknowledged that minor variations and changes can be made without materially affecting the spirit and scope of the invention as recited in the claims that follow.

EXAMPLES

Experiment 1 - Standard polyamideimide synthesis procedure

To a 250mL 4-neck round bottom flask equipped with nitrogen inlet and outlet, Vigreux reflux condenser, addition port, thermocouple, and overhead mechanical stirrer (with torque display), Nl,N4-bis[4-(2-aminoethyl)phenyl]benzene-l,4-dicarboxamide (APEA TPC 1) was added as a solid and rinsed in with solvent (10.809g, 26.856mmole, 1 eq). Subsequently, 4,4’-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) (11.931g, 26.856mmol, 1 eq), isoquinoline (0.57g, 4.41mmol, 0.08 eq relative to anhydride amount) and 150mL (m-Cresol) were added. The flask was heated to 160 °C for 4-6 hours.

After two hours, the flask was allowed to cool to room temperature. The flask contents were then precipitated into 4L of EtOH/fEO mixture. The precipitate was collected, blended in fresh EtOH/fEO and filtered, producing a fine white colorless powder of the polyamide-imide (PAI).

The reaction was repeated with amounts of with various combinations of the listed diamines and dianhydrides.

When it comes to the preparation of a polyamide-imide film, a solvent cast approach can be used. Polyamide-imide material can be dissolved in a solvent at a concentration ranging from 10 to 20 weight percent to form a varnish. Solvents can be N,N- dimethylacetamide (DMAc), Cyclopentanone (CPN), Cyclohexanone (CHN), y- Butyrolactone (GBL), or Acetophenone (PhAc). The varnish can be coated on a flat surface such as a glass plate or a flexible carrier substrate and subsequently be dried. After the initial drying step, the film can be delaminated from the flat surface and further processed.

Experiment 2 - Preparation of Polyamide-imide films

PAI films of the powders from Experiment 1 were prepared by first dissolving a portion of the powder in solvent (DMAc) at an approximate concentration of 10-20wt% to produce a colorless viscous varnish. The varnish was then coated onto a glass substrate via a doctor blade and heated at a temperature of 80°C for 30 minutes to produce a ‘wet’ PAI film.

The film was then removed from the plate and mounted into a stainless steel frame and baked under vacuum at 250°C for 12 hours, producing a dry, final colorless PAI film.

Characterization of polyamide-imide films

Polymer films obtained using the method described in Experiment 2 were characterized for their optical, thermal and mechanical properties using the following methods:

Film thickness - The thickness of a polyamide-imide film was measured using a Mahr, 2057551 Marameter XLI-57B-15 Portable Thickness Gage. Typically, 6 to 21 measurements were taken across the film and the average value was reported.

Color and Optical Transparency - The optical properties (e.g., percent transmittance, color, haze, R*) of a polyamide-imide film were measured using spectrophotometry. The percent transmittance of the polyamide-imide film was measured using a Shimadzu UV-2700 equipped with an integrating sphere (ISR-2600). Typically, films were inserted into a film sample holder and transmittance was measured from 800 nm to 200 nm using a slit width of 5 nm with the transmittance at 380nm and 400nm (T38o% and T4oo%) reported. Maximum transmission was also measured at 550nm (T _max ). The color and haze of a polyamide-imide film was measured using an X-rite Ci7800 spectrophotometer. Typically, a film sample was placed in a 25 mm sample holder and a Class I continuous wave 532 nm laser was flashed through the sample to measure direct and total transmittance as well as haze. The average of three measurements was reported. Yellow index (YI) was measured according to ASTM E313-20. Haze was determined according to ASTM D1OO3-13. The R* of a polyamide-imide film was measured using an Axometrics AxoScanTM Mueller Matrix Polarimeter. Typically, the film R* is measured by taking two axis out-of-plane retardance measurements at 550 nm wavelength in increments of 10° up to a maximum tilt angle of 50°; several spots are measured per film and the lowest R* value is reported.

Thermal properties - Incomplete imidization, residual solvent and thermal stability Ta (1%) were assessed using thermogravimetric analysis utilizing a TA Instruments Discovery TGA550. Typically, a few milligrams of polymer film were placed in a TGA pan which was heated at a rate of 10°C/min to 550°C under a nitrogen purge of 40-60 mL/min. The temperature at which 1% mass loss was achieved is recorded as the Ta (1%); for dry films (i.e., fully imidized, no residual solvent) this would typically occur in the 375-450°C temperature range for these materials. The glass transition (T _g ) of a polyamide-imide film was measured using dynamic mechanical analysis utilizing a TA Instruments Discovery DMA850 equipped with a film/fiber accessory. Typically, a 5 x 30 mm sample was die punched and loaded into the film/fiber accessory clamp; the film was heated at 5°C/min rate to 350-400°C in a nitrogen purged atmosphere under a 0.1% strain oscillated at 1Hz. The glass transition measurement was determined from the onset of the drop in storage modulus and/or the tan 6 maximum. The glass transition and coefficient of thermal expansion (CTE) of a polyamide-imide film was measured using thermal mechanical analysis utilizing a TA Instruments TMA Q400 with a film/fiber accessory. Typically, a 5 x 30 mm sample was used for testing. The sample was heated at 3 °C/min to 350-400 °C under a nitrogen purge of 50 mL/min with a load of 0.5 g per film thickness in um. CTE can be calculated using the slope of the line between 100-200°C. The T _g was calculated by measuring the temperature at which elongation of the sample occurs.

Mechanical properties - The tensile modulus, tensile strength, Young’s modulus, and elongation at break (EaB) were measured using an Instron 5967 with a 500 N load cell.

Typically, the specimens were tested following ASTM 1708. The sample dimensions follow those listed in ASTM 1708 and thickness was measured for each film utilizing a Mahr GmbH 1086Ri 25/0, 0005mm (1’7.00002”). Measured force and sample displacement were used by the Instron to calculate the modulus, tensile strength, and elongation at break. Elongation at break was tested following ASTM D638-14 and tensile modulus via ASTM D638-14.

Table of properties

¹ Nl,N4-bis[4-(2-aminoethyl)phenyl]benzene-l,4-dicarboxamide = APEA TPC 1 Nl,N4-bis[2-(4-aminophenyl)ethyl]benzene-l,4-dicarboxamide = APEA TPC 2

Structure; IV - intrinsic viscosity; res. sol. - residual solvent; T380 - transmittance at 380 nm; T400 - transmittance at 400 nm; T _max - maximum transmittance (-550 nm); YI - yellow index; H - Haze; Young’s modulus; T _g - glass transition temperature.

Note that not all of the activities described above in the general description or the examples are required, that a portion of a specific activity may not be required, and that one or more further activities may be performed in addition to those described. Still further, the order in which activities are listed is not necessarily the order in which they are performed.

In the foregoing specification, the concepts have been described with reference to specific embodiments. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the invention.

Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any feature(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature of any or all the claims. After reading the specification, skilled artisans will appreciate that certain features are, for clarity, described herein in the context of separate embodiments, and may also be provided in combination in a single embodiment. Conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any subcombination. Further, references to values stated in ranges include each and every value within that range.