New chitin-based polymer hybrids. 3 - Miscibility of chitin-graft-poly(2-ethyl-2-oxazoline) with poly(vinylalcohol)

The miscibility of blends of poly(vinyl alcohol) (PVA) with chitin-graft-po ly(2-ethyl-2-oxazoline) (1) and poly(2-ethyl-2-oxazoline) homopolymer (PEtO ZO) was investigated. Calorimetric results showed a single glass transition temperature (T-g) in the entire range of compositions for both blend syste ms, which indicated that PVA is miscible with both the graft copolymer 1 an d PEtOZO. The T-g of PVA is also shifted to lower temperature upon blending with the graft copolymer 1. IR analysis revealed the existence of specific interactions via hydrogen bonding between the hydroxyl groups in PVA and t he carbonyl groups in the poly(2-ethyl-2-oxazoline) side chain of graft cop olymer 1. The results show that the interaction of graft copolymer 1 with P VA is increased by introduction of longer poly(2-ethyl-2-oxazoline) side ch ains. Thermal decomposition (TG) measurements supported the compatibility o f PVA with graft copolymer 1 and with PEtOZO, and showed that the thermal s tability of PVA is improved upon blending with 1 or PEtOZO.