Characteristic Bands and Correlation Filters for 2D-COS IR Study of Solution Crystallization Process of Biodegradable Polyesters

Wednesday, October 8, 2025

2:10 PM - 2:30 PM EDT

Location: Meeting Room #2

Presenting Author(s)

IN

Isao Noda, PhD

Affiliated Professor
University of Delaware
Newark, Delaware, United States

Non-Presenting Author(s)

YP

Yeonju Park

Associate Professor
Kangwon Natonal University
Chuncheon, Kangwon-do, Republic of Korea
YJ

Young Mee Jung

Professor
Kangwon Natonal University
Chuncheon, Kangwon-do, Republic of Korea

In fifteen words or less, explain the significance of this contribution (Novel Aspect).: Advanced analysis of different spectral regions of bioplastics reveal different aspects of crystal formation processes

Abstract Text: We introduced last year a technique called correlation filters (CF) to selectively attenuating the contributions of overlapping spectral signals. We applied this tool to analyze the dynamic spectral changes of a chloroform solution of biodegradable polyester, poly(3-hydroxybutyrate-co-3-hydroxyhexanate), undergoing the solvent evaporation and subsequent crystallization of the polymer. While the analysis of this system involving several similar parallel processes was challenging, the overlapped dynamics of components was successfully separated using the CF technique. The construction of CF requires a selection of a set of spectral intensity variation signals arising from the so-called characteristic bands, which are least synchronously correlated with each other. Subjective visual observation of asynchronous cross peaks was previously used for this purpose with some level of uncertainty. Recently, a new systematic hierarchical search procedure for the identification of characteristic bands based on 2D-COS using a series of horizontal slices of correlation spectra has been developed. Using this technique, CFs are more reliably reconstructed to revisit the same dataset for the solution crystallization process. Furthermore, 2D-COS study of the process is then extended to examination of the C-H stretching and fingerprint regions of ATR IR spectra beyond the carbonyl stretching region. Based on the improved CF analysis and 2D hetero-mode correlation study, we discovered an intriguing observation that each spectral region represents surprisingly different and unique aspects of the progression of crystal formation revealed at the molecular level.