Degradation of poly(1,3‐dioxolane). Depolymerization versus hydrolysis

Abstract

There is renewed interest in polymers of 1,3‐dioxolane (DXL), especially as components of degradable polymer networks. DXL, a five‐membered cyclic acetal, is easily available on a commercial scale. Due to the relatively low strain of the five‐membered ring, its polymerization proceeding by a cationic mechanism is reversible. Above the ceiling temperature in the presence of an acid catalyst, it therefore undergoes depolymerization and this is one of the possible ways of degradation. On the other hand, monomeric units within the poly(1,3‐dioxolane) (PDXL) chain are connected by acetal bonds that are susceptible to acid‐catalyzed hydrolysis and this offers an alternative route for PDXL chain degradation. Polymer networks with connecting PDXL blocks are designed as commodity plastic materials but also as gels intended for biomedical applications. In both applications the possibility of gel disintegration by controlled degradation of connecting PDXL blocks is advantageous. The degradation in the two instances should proceed under different conditions, however. Degradation of commodity plastic material may proceed at higher temperatures in ‘dry’ conditions while biomaterials should degrade at mild physiological temperatures in an aqueous environment. In published papers, the distinction between the two routes of degradation is not always considered. In the present mini‐review, both mechanisms of degradation are presented and the available information on PDXL bloc degradation is critically evaluated. © 2023 Society of Industrial Chemistry.

Emerging Trends in the Chemistry of End-to-End Depolymerization

“…A complete analysis of stabilities of promising depolymerizable systems is required, as minor structural changes either on the backbone or side-chain would affect the depolymerizability as manifested by the strong influence of geminal disubstitution on T c . Moreover, any undesirable degradation imparted by hydrolysis, acid, base, light irradiation, or oxidation for real applications would possibly result in alterations from the as-designed depolymerization pathways . Moreover, high-efficiency and facile methodologies to incorporate functional moieties including responsive end-caps into depolymerizable backbones without compromising depolymerization capability requires more efforts .…”

“… 94 Moreover, any undesirable degradation imparted by hydrolysis, acid, base, light irradiation, or oxidation for real applications would possibly result in alterations from the as-designed depolymerization pathways. 155 Moreover, high-efficiency and facile methodologies to incorporate functional moieties including responsive end-caps into depolymerizable backbones without compromising depolymerization capability requires more efforts. 156 On the other hand, other depolymerizable systems that are not discussed here, including polycarbonates, 43 polyamides, 92 polyurethanes, 157 and polysaccharides, 158 also show widely attainable properties and depolymerizations.…”

Synthesis and polymerization of cyclic formals of oligooxyethylene diols

“…The kinetics and mechanism of cationic ring‐opening polymerization of DXL are well established 2,3 . PDXL is a degradable polymer, and its degradation may proceed either by depolymerization or by hydrolysis 4 . Chemical depolymerization of poly‐DXL, even from a mixed plastic waste, leads to starting material (DXL), which may be repolymerized 5 .…”

“…2,3 PDXL is a degradable polymer, and its degradation may proceed either by depolymerization or by hydrolysis. 4 Chemical depolymerization of poly-DXL, even from a mixed plastic waste, leads to starting material (DXL), which may be repolymerized. 5 Although polymerization of DXL was patented already in the forties of the 20th century 6 in the next few decades, there was limited interest in this process.…”