Speaker Name: Dr. Supriya Gupta (Lawrence Berkeley National Laboratory)
Date: 15-10-2025 (Wednesday)
Time: 2:30 PM
Venue: LC002
Abstract: Block copolymers are fascinating materials by virtue of their ability to self-organize into a rich variety of nanostructures with superior physico-chemical properties. The ordered phases formed by the dissimilar blocks exhibit tremendous potential to produce advanced functional nanomaterials for fast-emerging applications such as drug delivery, optoelectronic devices, nanoreactors, and nanofiltration. The incompatibility between constituent blocks and the block fraction provide tunable parameters for designing diverse nanostructures. The present study focuses on creating highly ordered, novel nanostructures using both computational and experimental approaches. Computationally, self-consistent field theory has emerged as a powerful tool for predicting equilibrium ordered nanostructures in inhomogeneous polymer systems. While the number of ordered phases in diblock copolymers is limited, many novel phases can be generated by altering polymer architecture or imposing geometric confinement.
This study elucidates the role of chain architecture and confinement geometry in the ensuing self-assembled phases. Structural frustration and confinement-induced entropy loss, combined with domain curvature, give rise to a variety of exciting novel phases such as helical and toroidal microstructures not observed in bulk systems. In particular, the mikto-arm star block copolymer under confinement provides myriads of three-dimensional ordered phases ranging from multi-component helices to honeycomb structures by tuning the block fractions and the degree of confinement. A comprehensive understanding of the self-assembly behavior enables the design of novel nanostructured materials with tailored properties. In a selective solvent, diblock copolymers form micelles.
Experimentally, core–shell block copolymer (BCP) micelles are formed and equilibrated by thermal annealing. Mechanistically, BCP micelles equilibrate through fusion, fragmentation, and chain exchange processes. The present study investigates the fragmentation kinetics of BCP micelles to attain equilibrium size. The role of the driving force in the timescale of micellar fragmentation is examined using in-situ DLS measurements, complemented with SAXS and TEM. A novel protocol to expedite the fragmentation of super-micelles is presented. The advanced X-ray scattering technique to probe the local orientational order of polymer segments grafted onto nanoparticle surfaces will also be briefly discussed. The polarized soft X-ray scattering reveals nanoscale polymer organization, enabling the design of advanced functional nanomaterials with tunable properties.