Synthesis and characterization of poly(N-acyl or N-aroyl ethylenimines) containing various pendant functional groups .2. Copolymers with pendant hydroxyl groups

Poly(N-acylethylenimines) with hydroxyl groups randomly attached to the end of the side chains were synthesized from decenyl/heptyl oxazoline random copolymers. The terminal olefin groups in the polymer side chains react quantitatively with 9-borabicyclo[3.3.1]nonane (9-BBN) in THF solvent. The hydroborated polymers can be oxidized and transformed to the polymers with -OH in their side chains. The polymer backbone is very stable in the hydroboration and oxidation reaction environment. The polymers were named as DH-OH or DH(m/n)-OH, where m and n represent the calculated numbers of monomers with and without the -OH group, respectively. The DH(m/n)-OH copolymers were studied by DSC, wide-angle x-ray diffraction, contact angle measurement, and FT-IR. They are crystalline and show birefringence. In polymers with high concentration of hydroxyl groups, the -OH groups promote polymer crystallization due to their strong interactions. They have very high Delta H of fusion, sharp crystallization peaks, and small supercoolings. Wide-angle x-ray diffraction study of these polymers demonstrated that their alkyl side chains are not fully extended in crystalline domain as those in the DH copolymers. Data from advancing water/ethanol mixture contact angle measurement indicates that most of the -OH groups in the copolymers are buried and the polymer surface is mainly composed of methyl or methylene group. FT-IR study in the carbonyl stretching region proves that the -OH groups can bend back and form hydrogen bonding with the carbonyl groups in the polymer backbone. Though the DH-OH polymers show basically a hydrocarbon surface in a normal environment, both receding water contact angle and peel strength measurements demonstrate that the polymer surfaces can reorganize when they are in contact with a polar liquid. The buried -OH groups can be ''pulled'' out by polar agents such as water or tape adhesive. (C) 1996 John Wiley & Sons, Inc.