Lamellar structures in blends of amorphous–block–main-chain liquid crystal–block–amorphous copolymers and amorphous homopolymers: Effects of the amorphous homopolymer molecular weight

In this study, the lamellar forming T (5.5-39-5.5) and T (11-39-11) copolymers were blended with homoPEMA (Hz) with Mn of z kDa at a concentration of 20 wt% to give the two series of blends T (5.5-39-5.5)/Hz and T (11-39-11)/Hz. These blends were examined for microdomain morphology as a function of the molecular weight ratio of z/x. T (5.5-39-5.5)/Hz formed lamellar microdomains over the investigated z/x range of 0.6–3.8, whereas T (11-39-11)/Hz formed lamellae over a narrower range of 1.2–2.6. The lamellar spacing and the PEMA and LC lamellar thicknesses (dam and dLC) were constant over z/x and dam was greater than dam of the neat copolymer. However, the values of dLC for these two blends were different; T (5.5-39-5.5)/Hz had the same dLC as T (5.5-39-5.5), whereas T (11-39-11)/Hz had a smaller dLC than T (11-39-11). These lamellar thicknesses variations in the blends are discussed based on the conformations of the copolymer blocks and the accommodation fashion of the Hz additives.Graphical abstract

Source: Polymer - June 12, 2019 Category: Chemistry Source Type: research