Bottom-up patterning of polymers has emerged as a next-generation lithographic technique due to its advantages of low cost and spontaneous nanoscale order. One key requirement for nanostructured polymer films for practical applications is the ability to generate complex geometries including different shapes and diverse sizes across one substrate surface. The constraints on previous strategies indicate a limited control of the polymer chemistry within defined locations on a polymer film. True on-demand synthesis in polymer films integrated with self-assembly would enable exact hierarchical control over the resulting morphology, functionality, and properties. In this talk, I will demonstrate a photo-controlled in-film polymerization process in the presence of monomer vapor for synthesizing homopolymers in self-assembled BCP films. The homopolymers blend with BCP films and alter the nanopatterns by changing the underlying polymer chemistry and composition. Identical photopolymerization conditions with lower UV power intensity causes more expansion of domains due to addition of higher molecular weight homopolymers, leading to highly asymmetric nanopatterns for polymer photonic gels with broad wavelength range. As these altered nanostructures are locally near equilibrium, this method can be adapted and combined with other techniques for defect annihilation and ordering improvement. The region of in-film polymerization can be modulated by the location of irradiation using photomasks for obtaining distinct morphologies on one substrate, which provides a new platform for hierarchically manipulating nanopatterns from the self-assembled BCP thin film. With successful integration of polymer chemistry and self-assembly physics, in-film polymerization provides an exciting opportunity for on-demand synthesis as well as opening up a new area for radical polymerizations of monomers within such geometrically confined, swollen films

Simultaneous in-film polymer synthesis and self-assembly for hierarchical nanopatterns

256th National Meeting (2018)

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