Structurally Tailored Polymeric Assemblies Derived from Pyroglutamic Acid

Chowdhury, Pampa (2026) Structurally Tailored Polymeric Assemblies Derived from Pyroglutamic Acid. PhD thesis, Indian Institute of Science Education and Research Kolkata.

Text (PhD thesis of Pampa Chowdhury (19IP004)) 19IP004.pdf - Submitted Version Restricted to Repository staff only Download (9MB)

Abstract

The current investigation focuses on the coherent design, synthesis, and the exploration of pyroglutamic acid-based polymeric systems showing self-coacervation property and advanced self-assembly behavior. A central theme of this work is the development of nonionic, hydrogen (H)-bonding -driven coacervates as an alternate to conventional electrostatically driven structures, thus addressing key restrictions such as poor constancy under high ionic strength conditions. This study begins with a comprehensive understanding of macromolecule-based self-coacervation, accenting its vital ethics and broad pertinency. Unlike traditional complex coacervation, the systems discovered here rely on single-macromolecule-based phase separation, providing streamlined and adaptable platforms for building membrane-less compartments with tunable physicochemical properties. These systems are positioned as promising candidates for biomimetic applications such as protocell models, drug delivery systems, and soft functional materials. A key highpoint of this study is the successful expansion of pyroglutamic acid-functionalized nonionic homopolymers capable of undergoing H- bonding-driven, stimuli-responsive self-coacervation. These polymers exhibit reversible thermoresponsive phase transitions and form micron-sized liquid droplets under controlled conditions. These coacervates can effectively encapsulate diverse cargoes, including small molecules, anticancer agents, and proteins, and enable their controlled release in response to environmental triggers such as temperature, pH, and ionic strength. This begins a robust platform for creating responsive therapeutic delivery systems. The work further helps to understand the fundamentals of thermoresponsive behavior by exploring cosolvency effects in polymer/water/alcohol systems. The capacity to finely tune phase behavior through solvent composition, molecular weight, and additives provides valuable insights into polymer-solvent interactions and expands the scope of designing smart responsive materials with predictable phase transitions. Another significant contribution lies in the design of pyroglutamate-pendant block copolymers via RAFT polymerization-induced self-assembly (RAFT-PISA). This approach enables the formation of a wide range of complex nanostructures, including conventional morphologies (micelles, vesicles) as well as rare inverse and hierarchical architectures. The introduction of (H)-bonding interactions at the core–shell interface creates a unique “fuzzy” boundary, facilitating unprecedented morphological diversity and expanding the design space of polymeric nanostructures. Finally, the investigation demonstrates the practical applicability of these systems in adhesive materials. H-bonding-driven coacervates exhibit excellent viscoelastic properties, strong substrate adhesion, and adaptability to different surfaces. Notably, these adhesives maintain performance even in challenging environments, highlighting their potential as next-generation nonionic, biomimetic adhesive materials. Overall, this work establishes a versatile framework for designing nonionic, stimuli-responsive polymeric coacervates and self-assembled systems, bridging fundamental understanding with real-world applications in therapeutics, nanotechnology, and advanced materials science.

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