Abstract

Polymers are a soft material with diverse applications across a spectrum of technologies including, but not limited to, packaging, drug-delivery, optics, lithography and templating. This ubiquity stems from over a century of in-depth theoretical and experimental investigations relating polymer size, stiffness and architecture to their emergent material properties. Interestingly, unlike small organic molecules where solution behavior is predominantly a function of hydrophobicity, in polymers, adjusting the aforementioned features can have a dramatic impact on their interactions with neighboring molecules. In turn, this allows for a tunable parameter space enabling the ability to achieve specific engineering goals. Yet, while the impact of size, stiffness and architecture are well studied, an understanding of how helical (chiral) polymers perturb the underlying thermodynamics of self-assembly is lagging. In this dissertation I leveraged molecular dynamics (MD) simulations to validate a novel mathematical model (The “Kremer-Grest Helical Chain”) that connects the underlying differential geometry of ideal helices to established particle-based polymer and continuumscale models. This was then used to quantify the chirality of helical polymer chains while also enabling the coarse-graining of experimental polymers with excellent efficacy. Given its facile implementation in MD simulations, it was leveraged to explore the impact of helical chain shape on the disordered thermodynamics of block copolymer (BCP) melts, where comparison of experimental findings across multiple research groups have been contradictory. Here, free-energy calculations of helical BCP melts, simulated using the Kremer Grest Helical Chain resolved this disagreement by showing that perturbations in effective interactions are dependent on the underlying geometry of the helical block. Specifically, longer pitch polymers increase these interactions while short pitch helices reduce them.  These insights were directly used to probe phase transitions to ordered morphologies. Interestingly, when exploring the lamellar phase ordered-disordered transition it was found that certain helical models prefer to “bridge” across the lamellae, introducing nematic alignment and further perturbing the self-assembly process when compared to more traditional polymer systems. Therefore, investigations into the Onsager-like nematic phase transition are discussed, where I’ve leveraged active learning to expeditiously elucidate the mapping of helical polymer geometry to favorable conditions that promote liquid crystalline behavior. All in all, this dissertation provides 1) a mathematical model that describes the differential geometry of helical polymers and their relation to chirality and 2) a thermodynamic blueprint that enables helicity to be leveraged as an engineering control parameter for future materials development.

Publication Date

8-2026

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

Pratik Dholabhai

Advisor/Committee Member

Emiliano Brini

Campus

RIT – Main Campus

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