Comparative Analysis of Green Solvent Efficacy in Polymerization Catalysis

Thesis Abstract

This study addresses the escalating environmental impact and resource intensity of conventional solvents in polymerization catalysis by evaluating the performance and sustainability of green solvents in cross-metathesis and controlled radical polymerization processes. The aim is to compare the efficacy, selectivity, and process metrics of eco-friendly solvents against benchmark organic solvents across multiple polymerization systems, thereby identifying solvent regimes that minimize environmental footprint without compromising product quality. Specific objectives include (1) quantifying polymerization rate, molecular weight distribution, and polydispersity under green solvent conditions; (2) assessing catalyst activity retention and turnover frequency in presence of alternative solvents; (3) evaluating process metrics such as solvent recovery, energy consumption, and waste generation; (4) characterizing the physicochemical interactions between solvent polarity, hydrogen-bonding capacity, and catalyst performance; and (5) developing a decision-support framework for solvent selection in industrial polymerization. A mixed-methods design is employed. The study utilizes a laboratory experimental component with a factorial arrangement across three monomer systems (j- styrene, acrylate, and vinyl acetate) and three green solvents (ethyl lactate, 2-mom, and cyclopentyl methyl ether) alongside conventional solvents (toluene, THF) as controls (n = 9 treatment combinations per polymerization system, each conducted in triplicate, total N = 81 experimental runs). Reaction conditions are standardized at 60–85°C, with monomer concentration fixed at 1.5 M and catalyst loading at 0.5 mol% for metathesis and ATRP-like systems. Analytical instruments include GPC for molecular weight distribution, GC-MS for residual solvent and byproducts, NMR spectroscopy for structural confirmation, and DSC for thermal properties of resultant polymers. Kinetic data are modeled via nonlinear regression to extract apparent rate constants, while ANOVA and post hoc Tukey tests assess statistical significance across solvent groups. A life-cycle assessment (LCA) is conducted to compare environmental impacts, focusing on global warming potential, embodied energy, and waste intensity, using ISO 14040/14044-compliant methodology. To triangulate findings, computational solvation models and Hansen solubility parameters are used to rationalize solvent–catalyst–monomer interactions. Expected findings include that selected green solvents yield comparable or improved polymerization rates and narrower molecular weight distributions relative to conventional solvents, with reduced catalyst leaching and enhanced recyclability. Ethyl lactate and cyclopentyl methyl ether are anticipated to demonstrate favorable polarity and hydrogen-bonding profiles that stabilize transition states and suppress side reactions, leading to higher polymer yields and lower residual catalyst content. The study also expects a measurable decrease in waste generation and energy demand, reflected in LCA results, thereby supporting a lower environmental footprint for green-solvent–enabled polymerizations. Theoretical interpretation will integrate Green Chemistry principles with the enthalpy-entropy balance of solvation, as explained by Hansen parameters and linear solvation energy relationships, to explain observed performance differentials. Contributions to knowledge include (i) an empirical performance benchmark of green solvents across diverse polymerization systems, (ii) a validated methodological framework combining kinetic, material, and environmental metrics for solvent evaluation, and (iii) a decision-support tool linking solvent attributes to catalytic activity and eco-efficiency. The study advances understanding of solvent–catalyst synergy and provides actionable guidance for industry to adopt sustainable solvents without sacrificing product specifications or process economics. The main conclusion anticipated is that carefully selected green solvents can match or exceed the performance of traditional solvents in polymerization catalysis while delivering substantive environmental and process efficiency gains. Recommendations emphasize the development of solvent libraries aligned with catalyst systems, integration of real-time reaction monitoring for solvent optimization, and policy-oriented guidance for adopting green solvents at scale, including incentives for solvent recovery and waste minimization.