Effects of Conformational and Orientational Ordering in Polymer Crystal Nucleation

ABSTRACT

Many functional and commodity polymers crystallize incompletely. The properties of these materials are largely governed by the final semicrystalline morphologies, in which crystalline and amorphous domains coexist. Quantitatively modeling polymer crystallization is essential for optimizing the material properties, but remains unrealized. In this talk, I will discuss our recent efforts for better modeling of the polymer crystallization. Specifically, we have developed a model for predicting the thermodynamic driving force for polyethylene (PE) and isotactic polypropylene (iPP) crystallization. This model can rather accurately predict the bulk phase transition temperatures for iPP and PE of different molecular weights. Using the free energy model, atomistic simulations, and classical nucleation theory, we demonstrated the roles of conformational and orientational ordering in polymer crystal nucleation under both quiescent and flow conditions.

BIOGRAPHY

Wenlin Zhang received a B.S. degree in Chemical Engineering from University of Minnesota in 2012 and a Ph.D. in Chemical Engineering from the Pennsylvania State University in 2017 under the supervision of Scott Milner and Enrique Gomez. After working as a postdoctoral scholar with Ronald Larson at University of Michigan, he joined Dartmouth College as an Assistant Professor of Chemistry in 2020. His research focuses on applying multi-scale simulations and statistical mechanics to predict the assembly and properties of soft materials. The recognition of his work includes the Walter and Constance Burke Research Initiation Award (Dartmouth), the Petroleum Research Fund Doctoral New Investigator Grant (ACS), and the NSF CAREER Award.