Thermal Decomposition of Fungal Poly(β,l-malic acid) and Poly(β,l-malate)s

Abstract

The thermal decomposition of poly(beta,l-malic acid), poly(alpha-methyl beta,l-malate), and ionic complexes of the polyacid with alkyltrimethylammonium salts was studied by TGA, GPC, and FTIR and NMR spectroscopy. It was found that poly(beta,l-malic acid) depolymerized above 200 degrees C by an unzipping mechanism with generation of fumaric acid which is then partially converted in a mixture of maleic acid and anhydride. On the contrary, random scission of the main chain was found to happen in the thermal decomposition of poly(alpha-methyl beta,l-malate). On the other hand, ionic poly(beta,l-malate)s degraded through a well defined three-stage process, the first one being depolymerization of the poly(malate) main chain along with decomposition of the ionic complex. Decomposition of the previously generated alkyltrimethylammonium salts followed by unspecific cracking of the resulting nitrogenated compounds happened at higher temperatures. Mechanisms partially explaining the decomposition processes of the three studied systems were proposed according to collected data.

Thermal decomposition of microbial poly(γ-glutamic acid) and poly(γ-glutamate)s

“…Kinetic parameters resulting from this analysis are summarized in Table 2 showing that similar E values were obtained by both methods for the two polymers, which is in full agreement with the occurrence of a common degradation mechanism for the two polymers. It should be noted that the E values resulting in this study are of the same order as those reported for poly(malic acid) and poly(methyl b,L-malate) which were determined using the same thermogravimetric method [19]. …”

“…It is worthy mentioning that certain polyesters such as poly(caprolactone) [22] and poly(lactic acid) [23] are known to degrade also by such a type of mechanism with generation of caprolactone and lactide, respectively. Decomposition of poly(b,L-malic) and poly(methyl b,L-malate) is known to occur through unzipping depolymerisation too, although in this case the released products are mixtures of fumaric and maleic acids [19].…”

“…The purpose is to characterize their thermal behaviour and to understand as far as possible the reaction mechanisms underlying the degradation. The approach followed in this study is the same that we previously used in the analysis of poly(b,L-malic) acid and polymalates, whose results have been recently reported [19].…”

Synthesis, Degradability, and Drug Releasing Properties of Methyl Esters of Fungal Poly(β,L‐malic acid)

“…Both onset and maximum rate decomposition temperatures are lower for the partially methylated products than for either of the two homopolymers. We reported recently on the thermal degradation of PMLA and PMLA-Me [17] showing that different decomposition mechanisms operate in each case. Decomposition of the polyacid takes place through an unzipping mechanism with the release of fumaric acid whereas the polymalate degrades by a random scission process leading to oligomeric fragments.…”

Development of materials and technologies for control of polymer recycling

“…Portilla-Arias et al 114 reported that poly(b,L-malic acid) was depolymerized above 200 1C by an unzipping mechanism from chain ends with the generation of fumaric acid, which was secondary Materials and technologies for polymer recycling H Nishida converted into maleic acid and anhydride (Scheme 27). These aliphatic acids and anhydride are reused to be incorporated in many chemical products.…”