Additive manufacturing of aromatic thermoplastics from photocurable precursor salts

1. A polymer resin for ultraviolet-assisted direct ink write photopolymerization, the polymer resin comprising:

(i) a polyamic acid salt comprising repeat units having a structure according to the following formula:

wherein each occurrence of R″ comprises a photocrosslinkable group selected from the group having a structure according to the following formulas:

wherein each occurrence of R is independently selected from the group consisting of H, substituted and unsubstituted alkyl, substituted and unsubstituted heteroalkyl, and substituted and unsubstituted alkenyl;

wherein each occurrence of Ar is independently selected from the group

wherein each occurrence of X is a substituted or unsubstituted aryl or heteroaryl group; and

wherein each occurrence of Y is independently selected from the group consisting of O, S, C═O, C(CF 3 ) 2 , C(CH 3 ) 2 , SO 2 , and C≡C;

(ii) a photoinitiator suitable for initiating crosslinking of the photocrosslinkable groups when exposed to a light source of a suitable wavelength and intensity; and

(iii) a suitable solvent.

2. The polymer resin according to claim 1 , wherein each occurrence of X is selected from the group:

3. A polymer resin for ultraviolet-assisted direct ink write photopolymerization, the polymer resin comprising:

(i) a polyamic acid salt formed from the addition of a photocrosslinkable amine to a polyamic acid

(ii) a photoinitiator suitable for initiating crosslinking of the photocrosslinkable amine when exposed to a light source of a suitable wavelength and intensity; and

(iii) a suitable solvent;

wherein the polyamic acid is formed by the addition of a diamine to a dianhydride in a suitable precursor solvent and wherein the polyamic acid is not isolated from the suitable solvent prior to forming the polyamic acid salt.

4. The polymer resin according to claim 3 , wherein the photocrosslinkable amine is selected from the group consisting of:

wherein each occurrence of R 1 is independently —H or —CH 3 ;

wherein each occurrence of R 2 is independently —H, —CH 3 , or —CH 2 CH 3 ; and

wherein each occurrence of R 3 and R 4 is independently —H, an aliphatic group, or an aromatic group.

5. The polymer resin of claim 3 , wherein the suitable precursor solvent is selected from the group consisting of: N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAC), dimethylformamide (DMF), y-butyrolactone, mixtures with hydrocarbon solvents/aromatic hydrocarbon solvents, water, ammonia, and mixtures thereof.

6. The polymer resin of claim 5 , wherein the suitable precursor solvent is N-methyl-2-pyrrolidone (NMP).

7. The polymer resin according to claim 3 , wherein the polyamic acid has a viscosity ranging from about 100 Pa·s to 400 Pa·s.

8. The polymer resin according to claim 3 , wherein the diamine is selected from the group:

wherein A is O, CH 2 , CH 2 CH 2 , SO 2 , C(CF 3 ) 2 , C(CH 3 ) 2 , S, S—S, CH═CH, C═O, or N;

wherein A 1 is Cl, CH, OCH 2 , CH 2 , CH 2 CH 3 or aliphatic or aromatic;

wherein A 2 is CH 3 , CF 3 , SO 3 H, SO 3 Na, tert-butyl or aliphatic or aromatic;

wherein A3 is CH 3 , CF 3 , or OH;

wherein n is 1, 3, or 3; and

wherein X is aliphatic or aromatic.

9. The polymer resin according to claim 3 , wherein the dianhydride is selected from the group:

wherein Y is C═O, C(CH 3 ), C(CH 3 ) 2 , SO 2 , or C≡O; and

wherein R 1 is F, CH 2 Cl, CH 2 Br, CH 2 F, H, or CH 3 .

10. The polymer resin according to claim 1 , wherein the polymer has an average molecular weight of about 40000 g/mol to about 60000 g/mol.

11. The polymer resin according to claim 1 , wherein the polymer has a polydispersity of about 2 or less.

12. The polymer resin according to claim 1 , wherein the photocrosslinkable groups have a thermal decomposition temperature of about 350° C. or less.

13. The polymer resin according to claim 1 , wherein the photocrosslinkable groups comprise an acrylate, a methacrylate, or a combination thereof.

14. The polymer resin according to claim 1 , wherein the suitable wavelength is about 300 nm to 500 nm.

15. The polymer resin according to claim 1 , wherein the photointiator is a phosphine oxide.

16. A polymer resin according to claim 1 , further comprising a UV blocker.

17. The polymer resin according to claim 1 , wherein the viscosity of the polymer resin is between 400 and 1,000 Pa·s.