Synthesis and Oxidative Degradation of Leucine-Based Poly(diacylhydrazine)

TL;DR

This paper describes a new polymer made from leucine that is stable under normal conditions but quickly breaks down when exposed to a specific chemical.

Contribution

A novel on-demand degradable polymer based on leucine with high thermal and chemical stability is synthesized and characterized.

Findings

The polymer remains stable in air up to 286 °C and is inert to oxygen.

It rapidly degrades into carboxylic acid and nitrogen gas when treated with sodium hypochlorite.

The polymer exhibits a polymodal molecular weight distribution and large polydispersity index.

Abstract

Diacylhydrazine is thermally and chemically stable, and it remains inert to oxygen even at high temperatures. However, it is rapidly oxidized by sodium hypochlorite, leading to its decomposition into carboxylic acid and nitrogen gas. In the synthesis of a novel poly(diacylhydrazine) as an oxidatively degradable polymer, L-leucine methyl ester is acylated by terephthaloyl chloride. Subsequent hydrazination yields a bishydrazide monomer. The oxidative coupling polymerization of this monomer produces poly(diacylhydrazine). The molecular structures of the products are confirmed by an 1H NMR analysis. A polymodal molecular weight distribution and a large polydispersity index are observed by GPC in all cases. A 10% weight loss temperature is noted at 286 °C in air by TGA. The obtained polymer is not oxidized by oxygen. No glass transition is observed below the decomposition temperature. Upon the treatment of the poly(diacylhydrazine) with sodium hypochlorite solution, decomposition occurs rapidly, resulting in monomeric carboxylic acid and nitrogen gas. The L-leucine-based poly(diacylhydrazine) serves as a novel on-demand degradable polymer with high levels of thermal and chemical stability during usage.

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