| 초록 |
The phase diagrams for mixtures of symmetric polystyrene-block-poly(n-butyl methacrylate) copolymer (PS-PnBMA) and PS (or PnBMA ) homopolymers with various molecular weights are presented, putting emphasis on the molecular weight of added homopolymers. For the study, PS-b-PnBMA copolymers having lamellar microdomains, and a series of polystyrene (PS) and poly(n-butyl methacrylate) (PnBMA) were used to prepare PS-PnBMA/PS and PS-PnBMA/PnBMA binary blends, via solvent casting. Phase diagrams were constructed experimentally for mixtures of PS-b-PnBMA block copolymer and homopolymer PS or PnBMA using the results of polarized optical microscope (POM) and small angle x-ray scattering (SAXS), which allowed us to determine the boundary between the microphase separated state (M1) of block copolymer and disordered state (L1), and cloud point measurements, which allowed us to determine the two-phase mixture (L1+L2) with L1 being disordered block copolymer and L2 being macrophase-separated homopolymer. Experimentally determined apparent lower disordered-ordered temperature (LDOT) decreased with increasing homopolymer molecular weight. Microphase separation was observed even when the molecular weight of the homopolymer is much larger than that of the miscible block copolymer segment. It was investigated on the effects of molecular weight and concentration of added homopolymers on the phase equilibria of ordered microdomains in mixtures of a block copolymer and homopolymers. |
