Porous/nanoporous PHT
Methods of forming nanoporous materials are described herein that include forming a polymer network with a chemically removable portion. The chemically removable portion may be polycarbonate polymer that is removable on application of heat or exposure to a base, or a polyhexahydrotriazine (PHT) or polyhemiaminal (PHA) polymer that is removable on exposure to an acid. The method generally includes forming a reaction mixture comprising a formaldehyde, a solvent, a primary aromatic diamine, and a diamine having a primary amino group and a secondary amino group, the secondary amino group having a base-reactive substituent, and heating the reaction mixture to a temperature of between about 50 degC. and about 150 degC. to form a polymer. Removing any portion of the polymer results in formation of nanoscopic pores as polymer chains are decomposed, leaving pores in the polymer matrix.
1. An article comprising a porous polymer having a plurality of hexahydrotriazine units, a plurality of hemiaminal units, or a combination thereof, the porous polymer having an average pore size less than about 100 nm and density less than about 1.5 g/cm 3 , wherein:
each hexahydrotriazine unit has the general structure
each hemiaminal unit has the general structure
wherein at least one starred bond of each hexahydrotriazine unit or hemiaminal unit is bonded to a divalent bridging group or a trivalent bridging group, and
the divalent bridging group or a trivalent bridging group is bonded to at least two hexahydrotriazine units or hemiaminal units.
2. The article of claim 1 , further comprising a plurality of carbon fibers disposed in the porous polymer.
3. The article of claim 1 , wherein each divalent bridging group has the structure
wherein L′ is a divalent linking group selected from the group consisting of —O—, —S—, —N(R′)—, —N(H)—, —R″—, and combinations thereof, wherein R′ and R″ independently comprise at least 1 carbon, and wherein each starred bond of each divalent bridging group is covalently bonded to a respective starred bond of a hexahydrotriazine unit or a hemiaminal unit.
4. The article of claim 1 , wherein the porous polymer also has a plurality of monovalent substituents.
5. The article of claim 1 , wherein the porous polymer includes a substituent having the general structure
wherein R is a substituted or unsubstituted alkyl, aryl, or alkoxy group having 1 to 50 carbon atoms, R′ is a substituted or unsubstituted alkyl or aryl group having 1 to 50 carbon atoms, and n is 1 to 1,000.
6. An article comprising a porous polymer having a plurality of hexahydrotriazine units, a plurality of hemiaminal units, or a combination thereof, the porous polymer having an average pore size of 20-100 nm and bulk density of 1.0-1.5 g/cm3, wherein:
each hexahydrotriazine unit has the general structure
each hemiaminal unit has the general structure,
wherein at least one starred bond of each hexahydrotriazine unit or hemiaminal unit is bonded to a divalent bridging group or a trivalent bridging group, and
the divalent bridging group or a trivalent bridging group is bonded to at least two hexahydrotriazine units or hemiaminal units.
7. The article of claim 6 , further comprising a plurality of carbon fibers disposed in the porous polymer.
8. The article of claim 6 , wherein each divalent bridging group has the structure
wherein L′ is a divalent linking group selected from the group consisting of —O—, —S—, —N(R′)—, —N(H)—, —R″—, and combinations thereof, wherein R′ and R″ independently comprise at least 1 carbon, and wherein each starred bond of each divalent bridging group is covalently bonded to a respective starred bond of a hexahydrotriazine unit or a hemiaminal unit.
9. The article of claim 6 , wherein the porous polymer also has a plurality of monovalent substituents.
10. The article of claim 6 , wherein the porous polymer includes a substituent having the general structure
wherein R is a substituted or unsubstituted alkyl, aryl, or alkoxy group having 1 to 50 carbon atoms, R′ is a substituted or unsubstituted alkyl or aryl group having 1 to 50 carbon atoms, and n is 1 to 1,000.
11. An article comprising a porous polymer having a plurality of hexahydrotriazine units, hemiaminal units, or both, the porous polymer having an average pore size of 20-100 nm and bulk density of 1.0-1.5 g/cm 3 , wherein the plurality of hexahydrotriazine units, hemiaminal units, or both are bonded together by a divalent aromatic linkage or a trivalent aromatic linkage.
12. The article of claim 11 , wherein the divalent aromatic linkage has the general structure
wherein L′ is a divalent linking group selected from the group consisting of —O—, —S—, —N(R′)—, —N(H)—, —R″—, and combinations thereof, and wherein R′ and R″ independently comprise at least 1 carbon.
13. The article of claim 11 , wherein the porous polymer also has a plurality of aromatic monovalent substituents.