Synthesis and Molecular Composites of Functionalized Polyisocyanates

Side chain functionalized polyisocyanates with ether, ester, and ketone groups, i.e. poly-(3-(benzyloxy)-n-propyl isocyanate) (PIET), poly(3-(benzyloxycarbonyl)-n-propyl isocyanate) (PIES), and poly(3-oxobutyl isocyanate) (PIK), were synthesized to enhance the possibility of forming miscible blends with hydrogen-bonding donor random coil polymers. While such blends do not form with poly(n-hexyl isocyanate) (PHIC) and a 91/9 copolymer of styrene and vinylphenol (PHS-9), several criteria are consistent with miscible blend formation with the functionalized polyisocyanates above. Infrared spectrometry demonstrates hydrogen bonding between the phenol hydroxyl groups and the polar side chain functions. The glass transitions of the blends are intermediate between those of PHS-9 and the polyisocyanate in certain composition ranges in which optical microscopy shows no evidence of birefringence or cloudiness. Optical activity properties and light-scattering measurements show that PIES and PIET are stiff helical macromolecules, as is well-known for PHIC. PIES was hydrogenolyzed to yield the unprotected polymer with carboxylic acid pendant groups. This polyelectrolyte was soluble in water with a pH 7 buffer and at higher pH's but with a depolymerization whose rate increased at higher pH.