{"title":"One- and two-step synthesis of paramylon mixed ester derivatives and the substitution effect on mechanical properties and seawater biodegradability","authors":"Ruiqi Li, Jin Ho Seok, Tadahisa Iwata","doi":"10.1016/j.polymdegradstab.2024.111037","DOIUrl":null,"url":null,"abstract":"<div><div>Paramylon acetate hexanoate (PaAcHex) with total DS=1.7 was prepared by one- and two-step methods with acetylation and hexanoylation in different order (denoted as AcHex and HexAc) in homogeneous DMAc/LiCl. The distribution of substitution at various ring carbon atoms (C2, C4, and C6) of PaAcHex synthesized by different methods was determined by <sup>1</sup>H NMR spectroscopic analysis. The AcHex mixed esters showed a higher DS of long-chain Hex on C2 and C4 than the other samples. All mixed esters were amorphous and their glass transition temperatures (<em>T</em><sub>g</sub>) were obtained from DMA measurements. PaAcHex with higher DS of hexanoate groups had lower <em>T</em><sub>g</sub> and their melt films showed higher flexibility at the same total DS for all three series of samples. PaAcHex films produced by the two-step (AcHex) method exhibited high toughness even with a low DS of hexanoate groups, whereas those synthesized by the one-step and two-step (HexAc) methods were weak and brittle. Biochemical oxygen demand tests indicated that the mixed esters prepared by the two-step (AcHex) method underwent a two-step degradation process, which may be related to the hexanoate groups on C2 and C4. Short–long chain acylation by the two-step (AcHex) method was found to be the optimal synthesis technique for polysaccharide esters that displayed favorable thermoplasticity and controllable seawater biodegradation behavior. These polysaccharide esters show promise as bioplastic materials.</div></div>","PeriodicalId":406,"journal":{"name":"Polymer Degradation and Stability","volume":"230 ","pages":"Article 111037"},"PeriodicalIF":6.3000,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Polymer Degradation and Stability","FirstCategoryId":"92","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S014139102400380X","RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"POLYMER SCIENCE","Score":null,"Total":0}
引用次数: 0
Abstract
Paramylon acetate hexanoate (PaAcHex) with total DS=1.7 was prepared by one- and two-step methods with acetylation and hexanoylation in different order (denoted as AcHex and HexAc) in homogeneous DMAc/LiCl. The distribution of substitution at various ring carbon atoms (C2, C4, and C6) of PaAcHex synthesized by different methods was determined by 1H NMR spectroscopic analysis. The AcHex mixed esters showed a higher DS of long-chain Hex on C2 and C4 than the other samples. All mixed esters were amorphous and their glass transition temperatures (Tg) were obtained from DMA measurements. PaAcHex with higher DS of hexanoate groups had lower Tg and their melt films showed higher flexibility at the same total DS for all three series of samples. PaAcHex films produced by the two-step (AcHex) method exhibited high toughness even with a low DS of hexanoate groups, whereas those synthesized by the one-step and two-step (HexAc) methods were weak and brittle. Biochemical oxygen demand tests indicated that the mixed esters prepared by the two-step (AcHex) method underwent a two-step degradation process, which may be related to the hexanoate groups on C2 and C4. Short–long chain acylation by the two-step (AcHex) method was found to be the optimal synthesis technique for polysaccharide esters that displayed favorable thermoplasticity and controllable seawater biodegradation behavior. These polysaccharide esters show promise as bioplastic materials.
期刊介绍：
Polymer Degradation and Stability deals with the degradation reactions and their control which are a major preoccupation of practitioners of the many and diverse aspects of modern polymer technology.
Deteriorative reactions occur during processing, when polymers are subjected to heat, oxygen and mechanical stress, and during the useful life of the materials when oxygen and sunlight are the most important degradative agencies. In more specialised applications, degradation may be induced by high energy radiation, ozone, atmospheric pollutants, mechanical stress, biological action, hydrolysis and many other influences. The mechanisms of these reactions and stabilisation processes must be understood if the technology and application of polymers are to continue to advance. The reporting of investigations of this kind is therefore a major function of this journal.
However there are also new developments in polymer technology in which degradation processes find positive applications. For example, photodegradable plastics are now available, the recycling of polymeric products will become increasingly important, degradation and combustion studies are involved in the definition of the fire hazards which are associated with polymeric materials and the microelectronics industry is vitally dependent upon polymer degradation in the manufacture of its circuitry. Polymer properties may also be improved by processes like curing and grafting, the chemistry of which can be closely related to that which causes physical deterioration in other circumstances.
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