Postdoctoral Researcher, Penn State
Presented: December 3 and 4, 2020
“Soft materials from block copolymer self-assembly: from bioinspired membranes to hierarchically-structured hydrogels”
Due to advancements in theoretical understanding and synthetic methods, block copolymers have found widespread applications ranging from uses in commodity products to highly-engineered devices. In this presentation, I will talk about innovative strategies for preparing bioinspired soft materials based on block copolymer self-assembly. In the first part, I will introduce a biomimetic strategy to construct channel-based membranes inspired by nature. In living systems, cell membranes control mass, energy, and information flow to and from the cell with extremely high selectivity and efficiency, a feat unmatched by current synthetic membranes.
To fabricate channel-based membranes, ABA triblock copolymer lamellae were used as a scalable and robust replacement of lipid bilayers for aligning the channel molecules while maintaining their molecular-level transport functions. By coassembly of block copolymers with either artificial channels or natural channels, we were able to synthesize nanofiltration membranes with sharp selectivity profiles as well as uncharged ion exchange membranes exhibiting ion selectivity. The strategy reported here could promote the construction of a range of channel-based membranes and sensors with desired properties, such as ion separations, stimuli responsiveness, and high sensitivity. In the second half of the presentation, I will talk about a universal and quantitative method, named rapid-injection, for fabricating and controlling physically crosslinked block copolymer hierarchically-ordered hydrogels. Plasmonic nanocomposite hydrogels containing gold nanoparticles and hierarchically-ordered hydrogels exhibiting structural colors were assembled within one minute using this rapid-injection technique.
Surprisingly, the rapid-injection hydrogels display superior mechanical properties and can be further processed into shape-memory materials. These works provide new inspirations for applying block copolymer materials in technologically relevant areas such as water filtration, drug delivery, tissue engineering, and soft robotics.
Chao Lang, Ph.D., Postdoctoral Researcher, Penn State
Chao Lang received his B.S. in chemistry (minor in biotechnology) in 2011 and doctorate in polymer chemistry and physics in 2016 at Jilin University. His Ph.D. conducted under the guidance of Professor Junqiu Liu on biomimetic channels and transporters resulted in the first report on synthetic transmembrane channels made from helical polymers.
As a postdoctoral researcher, he worked in the labs of professors Manish Kumar and Robert Hickey at Penn State. At Penn State, he has developed a block copolymer thin-film platform for fabricating channel-based membranes, which can be used for incorporating both artificial and biological channels. Focusing on block copolymer self-assembly, he has also established a universal and quantitative method, rapid-injection, for preparing different colloidal block copolymer hierarchical structures (micelles, microgels, and hydrogels) during non-equilibrium processing conditions. He is now working on light-weight artificial muscles based on polymer crystallization.