Ring-opening Polymerization Of Glycolide Research Articles

One‐Step Solvent‐Free Synthesis of Polyglycolic Acid from Sustainable C1 Feedstocks

AbstractPolyglycolic acid (PGA) is an aliphatic biodegradable polyester commonly synthesized through the ring opening polymerization of glycolide using mostly tin (II) octoate catalyst. Previously, a very convenient method for the synthesis of PGA from the cationic alternating copolymerization of formaldehyde (from trioxane) and carbon monoxide (CO) with triflic acid (TfOH) catalyst in dichloromethane (DCM) at 170 °C is described with 92% of yield. The need of using harmful DCM solvent for this polymerization directs to discover solvent‐free polymerization of formaldehyde and CO. Here, one‐step solvent‐free synthesis of PGA from the cationic alternating copolymerization of formaldehyde and CO is presented. Unlike the polymerization carried out in DCM solvent, optimum polymerization in solvent‐free conditions with TfOH catalyst is achieved in 80% of yield at 130 °C. It is considered that utilization of solvent‐free conditions and lower reaction temperatures compared to the previous report provides a more green and economic way of the synthesis of PGA. The method is also extended to copolymerization strategy by adding a minor amount of an epoxide compound to the reaction mixture, and PGA‐based copolymer with improved physical properties (such as solubility and appearance) is obtained in solvent‐free conditions.

A review on synthesis and biomedical applications of polyglycolic acid

Poly(glycolic acid) (PGA) is an essential biopolymer due to its thermal and mechanical properties and biodegradability which provide utility for medical applications and renewable industry. For biomedical applications, production of PGA with high molecular weight is an essential factor to possess adequate mechanical stability. Primary pathways for PGA synthesis are ring-opening polymerization of glycolide (ROP), direct polycondensation of glycolic acid, and solid-state polycondensation of halogen acetates. For PGA synthesis, different systems have been developed with using varying parameters including catalysis, initiators, solvents, and reaction temperature. This review summarizes the different synthesis pathways and physicochemical properties of PGA. Biomedical applications of PGA are also discussed.

Synthesis of polyglycolic acid copolymers from cationic copolymerization of C1 feedstocks and long chain epoxides

Polyglycolic acid (PGA), which is an important biodegradable polymer, can traditionally be synthesized through the ring opening polymerization of glycolide (with mostly using tin octanoate catalyst). Our previous studies revealed that PGA was alternatively synthesized with one-step cationic polymerization of formaldehyde from trioxane and carbonmonoxide (CO), sustainable C1 feedstocks obtainable from biomethanol or biogas. PGA and its copolymers can be mainly used for the biomedical applications due to their biocompatibility and biodegradability. In order to utilize PGA in other marketing materials such as packaging, PGA should be specifically engineered to improve its physical properties by a copolymerization strategy utilizing appropriate comonomers since PGA displays brown or beige color and is not soluble in most organic solvents due to its very high crystallinity. In this study; to improve on the physical properties of PGA, such as melting temperature and solubility, polymerizations of trioxane, CO and a minor amount of epoxides with long side chains were performed under the same reaction condition as PGA homopolymer synthesis (DCM solvent, at 800 psi, with triflic acid catalyst, reaction time of 72 h). The results have shown that optimum polymerizations were achieved at lower reaction temperatures than that of PGA homopolymer synthesis (110 °C versus 170 °C). The melting temperatures of all copolymers are lower, and the colors of the copolymers have become lighter than that of PGA homopolymer. The solubilities of obtained copolymers also increased by increasing side chain length of epoxides in the polymer backbone.

Alternative Approach for Synthesizing Polyglycolic Acid Copolymers from C1 Feedstocks and Fatty Ester Epoxides

Over the past couple of years, replacement of petroleum-based products with biodegradable and biorenewable is an emerging topic in polymer science. Biodegradable polyglycolic acid (PGA), the simplest aliphatic linear polyester, can traditionally be synthesized through the ring-opening polymerization of glycolide. Our previous studies revealed that PGA can alternatively be produced via one-step cationic polymerization of formaldehyde from trioxane and carbon monoxide (CO), which are potentially sustainable C1 feedstocks, under Bronsted acidic conditions. In this study, trioxane, CO, and a minor amount of fatty ester epoxides are copolymerized to improve on the physical properties of PGA, such as solubility and appearance, under the same reaction conditions for PGA homopolymer synthesis (in DCM, at 800 psi CO, with triflic acid catalyst, reaction duration of 72 h). The results have shown that the addition of minor quantities of epoxide comonomers vastly improved the solubility and decreased the melting temp...

Ring-opening polymerization of glycolide and rac-lactide, catalyzed by aryloxy magnesium complexes: DFT study of reaction profile and stereocontrol mechanism

DFT modeling shows that the most likely route of rac -lactide ring-opening polymerization, catalyzed by mono-aryloxy magnesium complexes, includes the formation of lower energy polymer-Mg chelates, which makes the formation of heterotactic polylactide preferable.

Cationic Ring Opening Polymerization of Glycolide Catalysed by a Montmorillonite Clay Catalyst

The ring opening bulk polymerization of glycolide catalyzed by Maghnite-H+ was reported. Maghnite-H+ is a montmorillonite sheet silicate clay, exchanged with protons. The effect of the amount of Maghnite-H+ and the temperature on polymerisation was studied. Increasing Maghnite-H+ proportion and temperature produced the increase in glycolide conversion. The kinetics indicated that the polymerization rate is first order with respect to monomer concentration. Mechanism studies showed that monomer inserted into the growing chains with the acyl–oxygen bond scission rather than the break of alkyl–oxygen bond.

Structure−Property Relationships of Copolymers Obtained by Ring-Opening Polymerization of Glycolide and ε-Caprolactone. Part 2. Influence of Composition and Chain Microstructure on the Hydrolytic Degradation

A series of glycolide/epsilon-caprolactone copolymers were compression molded and allowed to degrade in a pH 7.4 phosphate buffer at 37 degrees C. Degradation was monitored by various analytical techniques such as (1)H NMR, X-ray diffraction, DSC, CZE, ESI-MS, and inherent viscosity measurements. The results show that the degradation rate depends not only on the copolymer composition but also on its chain microstructure. Generally, copolymers with a higher C-G bond content or a higher degree of randomness exhibit higher degradation rates. Sequences with odd numbers of glycolyl units such as -CGC- and -CGGGC-, which result from the second mode transesterification, appear more resistant to hydrolysis. As a consequence, degradation residues obtained at the later stages of degradation are mainly composed of long glycolyl and caproyl sequences linked by -CGC- and -CGGGC- ones. The degradation rate of the copolymers depends also on the degree of crystallinity of each component which is related to the block length. The caproyl component can be preferentially degraded if it is in the amorphous state and the glycolyl component is semicrystalline.