Hongru Qiang, Xue Liang, Wenli Wang, Jiayun Jiang, Jianrui Li, Kai Hong, Jianzhong Du, Yunqing Zhu
{"title":"Exploiting Catalytic Steric Hindrance for Enhanced Tishchenko Polymerization: Toward Biorenewable Aromatic Polyesters","authors":"Hongru Qiang, Xue Liang, Wenli Wang, Jiayun Jiang, Jianrui Li, Kai Hong, Jianzhong Du, Yunqing Zhu","doi":"10.1021/acs.macromol.4c01955","DOIUrl":null,"url":null,"abstract":"Tishchenko reaction represents a highly atom-efficient method for synthesizing esters <i>via</i> aldehydes disproportionation, which holds significant promise in sustainable chemistry for polymerizing biorenewable dialdehydes into polyesters. However, previous Tishchenko polymerization attempts merely yielded oligomers with very low molecular weights due to intramolecular cyclization. To address this important challenge, we propose an efficient approach to leverage catalytic steric hindrance to achieve higher molecular weights. The investigation of six catalysts revealed that Al(OEt)<sub>3</sub>, with its three ethoxy groups initiating, imparts significant steric hindrance around the metal center and effectively prevents cyclization termination at the initial stage of polymerization, resulting in aromatic polyesters with a record <i>M</i><sub>w</sub> of 26.6 kg/mol. This breakthrough signals the potential of enhancing catalytic steric hindrance to overcome the low-molecular-weight limitation of Tishchenko polymerization. Building upon this discovery, we synthesized a series of biorenewable meta-substituted dialdehyde monomers (<b>M1</b>–<b>M4</b>) derived from vanillin to afford aromatic polyesters P(<b>M1</b>)–P(<b>M4</b>). These polymers offer tunable thermal properties through molecular weight and side chain flexibility adjustments, exhibiting high thermal stability (<i>T</i><sub>d,5%</sub> > 208 °C) and controllable glass transition temperatures (1–58 °C), and are degradable under mild conditions. This work highlights the importance of developing new methods to utilize readily available bioderived molecules, which is of great value for the sustainable economy.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":null,"pages":null},"PeriodicalIF":5.1000,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Macromolecules","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1021/acs.macromol.4c01955","RegionNum":1,"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
Tishchenko reaction represents a highly atom-efficient method for synthesizing esters via aldehydes disproportionation, which holds significant promise in sustainable chemistry for polymerizing biorenewable dialdehydes into polyesters. However, previous Tishchenko polymerization attempts merely yielded oligomers with very low molecular weights due to intramolecular cyclization. To address this important challenge, we propose an efficient approach to leverage catalytic steric hindrance to achieve higher molecular weights. The investigation of six catalysts revealed that Al(OEt)3, with its three ethoxy groups initiating, imparts significant steric hindrance around the metal center and effectively prevents cyclization termination at the initial stage of polymerization, resulting in aromatic polyesters with a record Mw of 26.6 kg/mol. This breakthrough signals the potential of enhancing catalytic steric hindrance to overcome the low-molecular-weight limitation of Tishchenko polymerization. Building upon this discovery, we synthesized a series of biorenewable meta-substituted dialdehyde monomers (M1–M4) derived from vanillin to afford aromatic polyesters P(M1)–P(M4). These polymers offer tunable thermal properties through molecular weight and side chain flexibility adjustments, exhibiting high thermal stability (Td,5% > 208 °C) and controllable glass transition temperatures (1–58 °C), and are degradable under mild conditions. This work highlights the importance of developing new methods to utilize readily available bioderived molecules, which is of great value for the sustainable economy.
期刊介绍:
Macromolecules publishes original, fundamental, and impactful research on all aspects of polymer science. Topics of interest include synthesis (e.g., controlled polymerizations, polymerization catalysis, post polymerization modification, new monomer structures and polymer architectures, and polymerization mechanisms/kinetics analysis); phase behavior, thermodynamics, dynamic, and ordering/disordering phenomena (e.g., self-assembly, gelation, crystallization, solution/melt/solid-state characteristics); structure and properties (e.g., mechanical and rheological properties, surface/interfacial characteristics, electronic and transport properties); new state of the art characterization (e.g., spectroscopy, scattering, microscopy, rheology), simulation (e.g., Monte Carlo, molecular dynamics, multi-scale/coarse-grained modeling), and theoretical methods. Renewable/sustainable polymers, polymer networks, responsive polymers, electro-, magneto- and opto-active macromolecules, inorganic polymers, charge-transporting polymers (ion-containing, semiconducting, and conducting), nanostructured polymers, and polymer composites are also of interest. Typical papers published in Macromolecules showcase important and innovative concepts, experimental methods/observations, and theoretical/computational approaches that demonstrate a fundamental advance in the understanding of polymers.