Microstructure analysis and thermal property of copolymers made of glycolide and ϵ‐caprolactone by stannous octoate

Abstract

Glycolide (GL) and ⑀-caprolactone (CL) were copolymerized in bulk at relatively high temperatures using stannous octoate as a catalyst. To investigate the relationship among microstructure, thermal properties, and crystallinity, three series of copolymers prepared at various reaction temperatures, times, and comonomer feed ratios were prepared and characterized by 1 H and 13 C NMR, DSC, and wide-angle X-ray diffraction (WAXD). The 600-MHz 1 H NMR spectra provided information about not only the copolymer compositions but also about the chain microstructure. The reactivity ratios (r G and r C ) were calculated from the monomer sequences and were 6.84 and 0.13, respectively. In terms of overall feed compositions, the sequence lengths of the glycolyl units calculated from the reactivity ratios exceeded those measured from the polymeric products. Mechanistic considerations based on reactivity ratios, monomer consumption data, and average sequence lengths are discussed. The unusual phase diagram of GL/CL copolymers implies that the copolymer melting temperature does not depend on its composition alone but rather on the nature of the sequence distribution. The DSC and WAXD measurements show a close relationship between polymer crystallinity and the nature of the polymer sequence.

Degradation of copolymers obtained by ring-opening polymerization of glycolide and ɛ-caprolactone: A high resolution NMR and ESI-MS study

“…Pack et al found r G ¼ 6.84 and r C ¼ 1.03 for bulk copolymerization in the temperature range 150e200 C using Sn(Oct) 2 as catalyst [21]. It is thus assumed that glycolide is first incorporated into growing chains.…”

High temperature reaction between poly(glycolic acid) and ε-caprolactone in ionic liquids

“…Since then, a number of research groups studied the copolymerization of GL and CL, using various initiating systems and various reaction conditions [6][7][8][9][10][11].…”

Copolymerization of L-lactide and ε-caprolactone in supercritical fluid

“…Such reductions in M n and monomer conversion were consistent with previous research on lactide polymerization, 18,20 and another study on lactone polymerization. 21 The optimum temperature commonly used in bulk copolymerization is 130 o C. 22 Effect of Monomer Concentrations. Monomer concentration is defined by monomer-to-solvent weight ratio.…”