2025 AIChE Annual Meeting

FTIR Analysis on Solvent-Cast PCL-B-PEO-B-PCL Films

Biocompatible and biodegradable polymers are of interest for a variety of reasons, including their applications in drug delivery. Hydrophilic poly-ethylene oxide (PEO) and hydrophobic poly-ε-caprolactone (PCL) are two commonly used semi-crystalline polymers that can be covalently bound in a variety of hierarchical assemblies. The properties of semi-crystalline copolymers are often affected by which polymer segment crystallizes first. In co-polymers where the crystallization and melting ranges are similar, this crystallization order can be manipulated. Two ways these manipulations can be achieved are by changing the hierarchical assembly and molecular weight ratios or changing the solvent used to suspend the polymer prior to casting. When casting from a solvent, one block will selectively precipitate out of the suspension as the solvent dries. Determining which block precipitates first depends on what solvent-solute interactions are more energetically favorable. While previous work has determined how solvents affect diblock PEO-b-PCL chains, other assemblies have not been thoroughly tested. One step towards a better understanding of how PEO and PCL interact is the analysis of a covalently bound tri-block configuration with both polymer types being of similar or equal molecular weight. This research shows, through hot-stage transmission FTIR, that the crystallization of 5k10k5k PCL-b-PEO-b-PCL is affected by the solvent type, with effects remaining even after the polymer has been fully melted and allowed to recrystallize.