Synthesis and Molecular Composites of Functionalized Polyisocyanates

Abstract

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 9l/9 copolymer of styrene and vinylphenol (PHS-91, 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 pHs but with a depolymerization whose rate increased at higher pH.

The Macromolecular Route to Chiral Amplification

“…Successful blending [38] of certain functionalized polyisocyanates with copolymers of styrene and vinyl phenol allowed this experiment to be carried out. A material was formed without birefringence, allowing measurement of the optical activity properties of the polyisocyanate in the solid state.…”

Synthesis and Anionic Polymerization of Isocyanates Bearing a Carbamate Group

“…However, only a few studies 14 -16 have been done on the polymerization of isocyanates with a polar functional group, and the polymerization of isocyanates with an active hydrogen except for an acetyl group 15 has not yet been reported. Polyisocyanates with a polar side group capable of making hydrogen bonds may be important since polar interactions between the side groups may strongly influence the helical structure of a polymer chain.…”

Formation of a True Molecular Composite using Optimal Hydrogen Bonding

“…Moreover, these results suggest that by increasing the spacing between functional groups that participate in intermolecular interactions, the extent of intermolecular interactions can be optimized and this in turn can induce miscibility in a blend containing a liquid crystalline polymer and an amorphous polymer. It should be emphasized that previous works [10,16] on rod/coil polymer mixtures by other authors have focussed on a single composition of VPh in the PS-co-VPh copolymer used for the blend. Alternatively, this article describes how varying the amount of VPh in the copolymer can optimize the extent of intermolecular hydrogen bonds between an LCP and an amorphous polymer.…”

“…[17] Poly[styrene-co-(4-vinylphenol)] (PS-co-VPh) random copolymers of 5, 10, 20, 30, and 50 mole percent (mol-%) VPh (M -n = 13 700, 20 700, 47 100, 22 100, 34 100 g/mol, respectively) were synthesized by free-radical polymerization of styrene and 4-acetoxystyrene using 2,29-azoisobutyronitrile (AIBN) as the initiator and the subsequent hydrolysis of the acetoxy groups to hydroxyl groups using hydrazine hydrate. [16] Molecular weights relative to polystyrene standards were determined in a Waters gel permeation chromatograph (GPC) equipped with ultrastyragel columns with a refractive index detector. N,N-dimethylformamide (DMF) was used as the elution solvent for the LCPU and tetrahydrofuran (THF) for the PS-co-VPh.…”

“…[13] In the case of a rod-like and coil polymer mixture, there is an additional tendency of the former to form liquid crystal regimes which excludes the coil polymer, thus further lowering miscibility. [14] Painter et al [10,15] and Green et al [16] have demonstrated that it is possible to form a thermodynamically stable molecular composite by incorporating hydrogen bonding between the LCP and amorphous polymer, which provides a favorable enthalpic contribution to the free energy. However, these isolated examples have not provided insight into how such miscible systems may be predicted and reproducibly created with a broad range of LCP and amorphous polymer structures.…”