Polyhemiaminal and polyhexahydrotriazine materials from 1,4 conjugate addition reactions
Polyhemiaminal (PHA) and polyhexahydrotriazine (PHT) materials are modified by 1,4 conjugate addition chemical reactions to produce a variety of molecular architectures comprising pendant groups and bridging segments. The materials are formed by a method that includes heating a mixture comprising solvent(s), paraformaldehyde, aromatic amine groups, aliphatic amine Michael donors, and Michael acceptors, such as acrylates. The reaction mixtures may be used to prepare polymer pre-impregnated materials and composites containing PHT matrix resin.
1. A polyhexahydrotriazine (PHT), comprising:
a plurality of trivalent hexahydrotriazine groups having the structure
and
a plurality of phenyl groups having the structure
wherein each wavy bond site of a given hexahydrotriazine group is covalently linked at a respective wavy bond site of a phenyl group, and each wavy bond site of a given phenyl group is covalently linked at a respective wavy bond site of a hexahydrotriazine group, and wherein at least one of A, B, C, D, and E is a chemical group that is a reaction product of a 1,4 conjugate addition chemical reaction.
2. The PHT of claim 1 , wherein at least one of A, B, C, D, and E is a Michael addition reaction product.
3. The PHT of claim 2 , wherein at least one of A, B, C, D, and E is a chemical group containing a Michael addition donor reaction product.
4. The PHT of claim 3 , wherein the Michael addition donor comprises a material selected from the group consisting of amines, thiols, sulphides, phosphines, phosphides carbanions, and alkoxides.
5. The PHT of claim 2 , wherein at least one of A, B, C, D, and E is a chemical group containing a Michael addition acceptor reaction product.
6. The PHT of claim 5 , wherein the Michael addition acceptor is selected from the group consisting of alpha-beta unsaturated esters, acrylates, methacrylates, alkyl methacrylates, cyanoacrylates, acrylonitrile, acrylamides, maleimides, vinyl sulfones, vinyl sulfoxides, vinyl sulfones, vinyl ketones, nitro ethylenes, vinyl phosphonates, acrylonitrile, vinyl pyridines, azo compounds, beta-keto acetylenes and acetylene esters.
7. The PHT of claim 2 , wherein less than three Michael addition reaction products are covalently bound pendant groups.
8. The PHT of claim 7 , wherein each Michael addition reaction product covalently bridges at least one hexahydrotriazine group to another hexahydrotriazine group.
9. The PHT of claim 2 , wherein at least one of A, B, C, D, and E comprises a Michael addition reaction product having a polymeric segment selected from the group consisting of poly(amides), poly(carbonates), poly(esters), poly(ether ketones) poly(ethers), poly(etherimides), poly(imides), poly(olefins), poly(siloxanes), poly(sulfones), halogenated polymers, poly(phenylenes), poly(urethanes) and copolymers thereof.
10. The PHT of claim 9 , wherein at least one polymeric segment has a repeating unit of at least two.
11. The PHT of claim 2 , comprising at least one polymer interpenetrating network.
12. The PHT of claim 11 , wherein the polymer interpenetrating network comprises a non-PHT polymer, and the non-PHT polymer comprises at least one of the Michael addition reaction products.
13. The PHT of claim 12 , wherein the non-PHT polymer is a radical-initiated polymer.