Self-Assembly Structures through Competitive Interactions of Crystalline-Amorphous Diblock Copolymer/Homopolymer Blends: Poly(epsilon-caprolactone-b-4-vinyl pyridine)/Poly(vinyl phenol)

Abstract

A series of immiscible crystalline-amorphous diblock copolymers, poly(epsilon-caprolactone)-b-(4-vinyl pyridine) (PCL-b-P4VP), were synthesized through combination of sequential ring-opening and controlled living free radical (nitroxide-mediated) polymerizations and then blended with poly(vinyl phenol) (PVPh) homopolymer. Miscibility and self-assembly morphologies mediated by hydrogen-bonding interactions of this new A-B/C type polymer blend are discussed in detail. Self-assembly morphologies of these immiscible PCL-b-P4VP diblock copolymers change through competitive hydrogen-bonding interactions with the increase of PVPh contents The SAXS profiles also reveal a sharp primary peak and highly long-range order reflections such as cylinder or sphere structure at relatively lower PVPh content, which is consistent with TEM images. DSC, WAXD, and FT-IR analyses provide positive evidence that the pyridine group of P4VP is a significantly stronger hydrogen-bond acceptor than the carbonyl group of PCL with the hydroxyl group of PVPh and results in the excluded and confined PCL phase.