About the Seminar:
Our interest in utilizing and incorporating strained rings in ladder-shaped molecular structures led to the development of unusual organic materials. We developed Catalytic Arene-Norbornene AnnuLation (CANAL) to synthesize rigid ladder polymers from readily available norbornenes and aryl bromides. Efficient CANAL polymerization produced rigid ladder polymers with molecular weights up to 1 MDa, contorted conformations, and various functionalities. These ladder polymers exhibited high microporosity (pore width < 1 nm) and surprisingly high thermal stability up to 400 °C without detectable Tg. Membranes from these polymers were fabricated for gas separation and understanding gas transport in glassy polymers.
In the quest for synthetic materials that transduce mechanical stimulation to multifaceted signals in response to force, we developed a unique family of insulating polyladderenes, which rapidly unzip under force into semiconducting polymers. The force-induced unzipping of macromolecular ladders opens new avenues for smart materials that transform their intrinsic properties drastically under stress and mechanistic understanding of mechanotransduction in polymers.
About the Speaker:
Yan Xia received his undergraduate degree from Peking University (’02) and MSc from McMaster University (’05). He then obtained his PhD in Chemistry from Caltech in 2010, working on cyclic and bottlebrush polymers under the guidance of Profs. Robert Grubbs and Julie Kornfield. Following his PhD, he worked as a senior chemist at Dow Chemical for one and a half years and then a postdoc associate with Prof. Brad Olsen at MIT Chemical Engineering. He joined the chemistry faculty at Stanford in the summer of 2013. His research interest lies in the design, synthesis, and manipulation of organic materials and polymers, driven by new synthetic capability, rational molecular design, and curiosity. He is a recipient of Terman Fellowship, ARO Young Investigator Award, 3M Non-Tenured Faculty Award, NSF CAREER Award, Thieme Chemistry Journals Award, and Cottrell Scholar Award.