(769g) Self Assembly of Coil-Hyperbranched Poly(styrene-block-acrylated epoxidized soybean oil) Block Copolymers

Lin, F. Y. - Presenter, Iowa State University
Hohmann, A. D., Iowa State University
Hernandez, N., Iowa State University
Cochran, E. W., Iowa State University
Biorenewable thermoplastic elastomers have shown its economic potential to substitute their petroleum counterparts. In this study we preset a series of coil-hyperbranched poly(styrene-b-acrylated epoxidized soybean oil) (PS-PAESO) diblock copolymers through reversible addition-fragmentation chain transfer (RAFT) polymerization, which demonstrate its competitiveness toward poly(styrene-b-butadiene-b-styrene) (SBS) in applications such as pressure sensitive adhesives and bitumen modification. Even with significant dispersity in both molecular weight and molecular architecture, triglyceride-based diblock copolymers undergo microphase separation. Through tuning the degree of acrylic functionality in AESO monomer, the influence of degree of branching of PAESO block can be shown on the phase diagram by constituting an additional parameter which has never been discussed before. By thoroughly understanding the self assembly behavior of PS-PAESO, the ability to adjusting the performance in applications will be enhanced. We have constructed a library of PS-PAESO polymers sampling the parameter space defined by the molecular weight, composition, and functionality of AESO. The self assembly behavior is demonstrated through dynamic shear rheology, transmission electron microscopy and the corresponding small angle X-ray scattering.