Abstract

Block copolymers can exhibit chirality at three different length scales – molecular chirality at the residue scale, conformational chirality at the molecular scale, and structural chirality at the mesoscale from the self-assembly of thousands of molecules. Unique morphologies have been formed due to chirality transfer, a phenomenon where chirality at smaller length scales imparts chirality to larger length scales. However, chirality does not always transfer, with chiral blocks existing in an achiral phase due to chiral frustration. The thermodynamics of the effects of chirality on block copolymer self-assembly is not well understood. This work demonstrates that coarse-grained models can effectively capture and explain the influence of chain conformation and repulsive interactions on chirality induction, transfer, and frustration while offering valuable insights into these phenomena. First, achiral triblock copolymers in the gyroid morphology are studied. The gyroid is stabilized with short homopolymer additions that prevent excessive chain stretching and provide more network tunability. Secondly, a model for chiral chain conformations is developed. A wide range of helical conformations is accessed and the model is matched to an experimental polypeptoid system. Finally, this model is expanded to investigate chiral diblock copolymers in the achiral lamellar phase. The interplay between the chains and the phase is found to depend on a variety of chain metrics such as chain stiffness and pitch. This work provides a perspective to compare and contrast different chiral polymer systems, providing explanations for different self-assembly behavior.

Library of Congress Subject Headings

Block copolymers--Conformation; Block copolymers--Structure; Chirality

Publication Date

4-25-2024

Document Type

Dissertation

Student Type

Graduate

Degree Name

Microsystems Engineering (Ph.D.)

Department, Program, or Center

Microsystems Engineering

College

Kate Gleason College of Engineering

Advisor

Poornima Padmanabhan

Advisor/Committee Member

Matt Miri

Advisor/Committee Member

Lishibanya Mohapatra

Campus

RIT – Main Campus

Plan Codes

MCSE-PHD

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