Mesoscale Block Copolymers

Abstract

Materials composed of well-defined mesoscale building blocks are ubiquitous in nature, with noted ability to assemble into hierarchical structures possessing exceptional physical and mechanical properties. Fabrication of similar synthetic mesoscale structures will offer opportunities for precise conformational tuning toward advantageous bulk properties, such as increased toughness or elastic modulus. This requires new materials designs to be discovered to impart such structural control. Here, the preparation of mesoscale polymers is achieved by solution fabrication of functional polymers containing photoinduced chemical triggers. Subsequent photopatterning affords mesoscale block copolymers composed of distinct segments of alternating chemical composition. When dispersed in appropriate solvents, selected segments form helices to generate architectures resembling block copolymers, but on an optically observable size scale. This approach provides a platform for producing mesoscale geometries with structural control and potential for driving materials assembly comparable to examples found in nature.

Drawing inspiration from nanoscale block copolymer architectures, mesoscale ribbons are patterned to generate alternating blocks of different chemical composition, thickness, and materials properties γ and E. These "mesoscale block copolymers" respond to the surrounding fluid environment to afford alternating ribbon–helix structures analogous to rod–coil block copolymers, adapting the block copolymer concept toward a new method of mesoscale conformational control.

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