Morphology Study of Polystyrene-Polybutadiene-polycaprolactone (PS-b-PB-b-PCL), Polybutadiene-Polycaprolactone (PB-b-PCL), and Polystyrene-Polycaprolactone (PS-b-PCL) Semicrystalline Block Copolymers

Abstract

Semicrystalline block copolymers containing one crystalline block, such as PCL, show more complicated morphologies than amorphous block copolymers. This is because the microstructure of semicrystalline block copolymers is determined by the interplay between the microphase-separation temperature, crystallization temperature, and glass transition temperatures of the respective blocks. This paper describes initial results of thermodynamic and kinetic effects associated with microphase separation and crystallization in as-cast semicrystalline (PS)0.62(PCL)0.38, (PB)0.2(PCL)0.8 and (PS)0.35(PB)0.15(PCL)0.5 block copolymers, where the subscripts denote the mass fraction of each block.Semicrystalline block copolymers (PS-b-PCL with Mn=209,000 g/mol, PB-b-PCL with Mn=146,000 g/mol and PS-b-PB-b-PCL with Mn= 150,000 g/mol) were prepared by anionic polymerization. Films were cast from 5% (mass fraction) solutions in toluene into ∼lmm thick films. A relatively slow solvent evaporation over approximately a 10 d period was achieved by partially covering the dishes containing polymer solutions.