Theoretical investigation of star diblock copolymer systems using the random phase approximation
摘要
The study of star A–B diblock copolymers has garnered growing attention due to their unique physicochemical properties, which are strongly governed by incompatibility effects between their constituent blocks. Unlike their linear counterparts, star-shaped architectures exhibit distinct behaviors in micellization and phase separation, making them attractive for advanced materials design. While linear diblock copolymers have been the subject of extensive theoretical and experimental investigations, systems with more complex topologies such as star polymers remain relatively underexplored from a theoretical standpoint. In this work, we investigate the static scattering of mixtures composed of star diblock copolymers and homopolymers. Specifically, we analyze the scattering behavior of star A-B diblocks copolymers in the melt state, mixed with homopolymers, and in solution using the Random Phase Approximation. In this approximation, the absolute intensity measured by small-angle neutron scattering is determined only by the structure factors of the core or corona part of the star polymer, which depends on the type of homopolymer in the mixture. The angular variations of the structure factors SBB(Q) and SAA(Q), accessible by neutron scattering when homopolymers A and B are added to the star diblock copolymers, are graphically illustrated for various values of physicochemical parameters. The results reveal the appearance of a correlation peak for all considered parameter values and a more or less significant dependence of the scattered intensity at the thermodynamic limit. These findings are in qualitative agreement with the experimental observations reported by Adhikari et al., underscoring the critical role of homopolymers in determining phase behavior.