Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada.
Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada.
J Am Chem Soc. 2023 Feb 15;145(6):3606-3614. doi: 10.1021/jacs.2c12668. Epub 2023 Feb 7.
Carotenoids are a class of biobased conjugated molecules that bear a resemblance to the substructure of polyacetylene, a well-known conductive but insoluble polymer. Solubility is an important physical attribute for processing materials using different techniques. To impart solubility in polymers, alkyl side chains are often included in the molecular design. While these design strategies are well explored in conjugated systems, they have not been implemented with carotenoids as a building block in polymers. Here, we show a series of carotenoid-based polymers with varying side chain lengths to tune solubility. Using carotenoid and -phenylenediamine-based monomers, degradable and biobased poly(azomethine)s were synthesized via imine polycondensation. Maximum solubilities corresponding to the varying alkyl chain lengths were quantitatively determined by ultraviolet-visible (UV-vis) absorption spectroscopy. Since carotenoids are biobased with known degradation products, the effect of acidic and artificial sunlight-promoted degradation was systematically investigated using UV-vis spectroscopy, H nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy, gel permeation chromatography (GPC), and high-resolution mass spectroscopy (HRMS). Our polymer system was found to have two modes of on-demand degradation, with acid hydrolysis accelerating the rate of polymer degradation and artificial sunlight generating additional degradation products. This work highlights carotenoid monomers as viable candidates in the design of biobased, degradable, and conjugated polymers.
类胡萝卜素是一类生物基共轭分子，其结构与聚乙炔的亚结构相似，聚乙炔是一种众所周知的导电但不溶的聚合物。溶解度是使用不同技术处理材料的重要物理性质。为了赋予聚合物溶解性，通常在分子设计中包含烷基侧链。虽然这些设计策略在共轭体系中得到了很好的探索，但它们尚未在聚合物中作为构建块应用于类胡萝卜素。在这里，我们展示了一系列具有不同侧链长度的基于类胡萝卜素的聚合物，以调节其溶解性。我们使用类胡萝卜素和 - 苯二胺基单体，通过亚胺缩聚合成了可降解和生物基的聚（亚胺）。通过紫外可见（UV-vis）吸收光谱定量确定了与变化的烷基链长度相对应的最大溶解度。由于类胡萝卜素具有已知的降解产物，因此系统地使用紫外可见光谱、H 核磁共振（NMR）光谱、红外（IR）光谱、凝胶渗透色谱（GPC）和高分辨率质谱（HRMS）研究了酸性和人工阳光促进降解的影响。我们的聚合物系统被发现具有两种按需降解模式，酸水解加速了聚合物降解的速率，人工阳光产生了额外的降解产物。这项工作强调了类胡萝卜素单体作为生物基、可降解和共轭聚合物设计的可行候选物。
