Synthesis of bio-based supramolecular gelators to act as thickeners in industrial applications

项目背景(确定问题及其对可持续性的重要性和相关性)在最近社会和环境压力增加，以及控制微塑料排放到环境中的新法规之后；工业界将极大的重点放在确保配方由易于生物降解的可持续材料制成。增稠剂是许多配方的关键成分，但它们通常由高分子量聚合物组成，例如聚丙烯酸，这种聚合物因其形成凝胶的能力非常低而受到青睐。不幸的是，这些高分子量聚合物的生物降解性很差，通常来自石化产品，而基于生物的聚合物替代品，如羟乙基纤维素，价格昂贵，需要大量提取。因此，出现的挑战是创造一种高分子量聚合物的替代品，这种聚合物是可生物降解的，设计时考虑了可持续性，并且在相同的重量百分比下具有相同的性能。建议的解决方案和方法建议通过设计具有通过超分子、非共价相互作用进行自组装的能力的低分子量结构(&lt；2000Da)，可以形成具有与基于聚合物的体系相似的性质的凝胶。当低分子量凝胶剂(LMWG)与溶剂混合并施加刺激时，非共价相互作用(如氢键、pi-pi堆积或van der-Waals力)可导致纤维的形成，这些纤维缠绕在一起并将溶剂分子包裹在基质中形成凝胶。由于这些纤维的主干是非共价的，可以通过施加另一种物理或化学刺激来打破它们，这些刺激可以根据废物处理的条件量身定做。主要的挑战之一是设计能够在水和丙二醇等极性溶剂中形成凝胶的低分子量凝胶，作为个人护理配方中的首选溶剂。在这些体系中，溶剂效应是复杂的，因此很难预测凝胶剂在不同溶剂体系中的行为。该项目的一个关键部分将侧重于扩展现有的结构-属性数据库，以改进机器学习和预测。该项目将从合成文献报道的凝胶剂开始，旨在通过“绿色”合成途径获得这些结构。利用前一项研究中获得的化学成分，该项目将转向从生物、废物、萜类、香草醛和大型藻类等原料中设计低分子量天然气。将对每种凝胶剂在不同溶剂系统和配方中的性能进行广泛的测试，并与聚合物配方进行比较。流变学筛选、光谱成像和毒理学研究都将是这项工作的关键组成部分。

Project background (identification of the problem and its importance and relevance to sustainability) Following a recent increase in social and environmental pressures, along with new regulations to control microplastic release into the environment; industry has put a huge focus on ensuring formulations are made from readily biodegradable, sustainable materials. Thickeners are a key component of many formulations however they are often formed of high molecular weight polymers, such as poly (acrylic acid), which are favoured for their ability to form gels at a very low weight percent. Unfortunately, these high molecular weight polymers have poor biodegradability, and are often sourced from petrochemicals, whilst bio-based polymer alternatives, such as hydroxyethyl cellulose, are costly and require heavy extraction. Thus, the challenge arises to create an alternative to high molecular weight polymers, that are bio-degradable, designed with consideration of sustainability, and that perform equally at a similar weight percentage. Proposed solution and methodology It is proposed that by designing low molecular weight structures (<2000Da) with the ability to self-assemble though supramolecular, non-covalent interactions, gels can be formed with similar properties to the polymer-based systems. When a low molecular weight gelator (LMWG) is mixed with a solvent and a stimulus is applied, non-covalent interactions (such as hydrogen-bonds, pi-pi stacking or van-der-waals forces) can lead to the formation of fibrils, which entangle together and entrap solvent molecules within the matrix forming a gel. Since the backbone of these fibrils are non-covalent, they can be broken by applying another physical or chemical stimulus, which could be tailored to conditions in waste-treatment. One of the main challenges is to design LMWG's that can form gels in polar solvents such as water and propylene glycol, as the preferred solvents in personal-care formulations. Solvent effects are complex within these systems and therefore the behaviour of gelators in different solvent systems is difficult to predict. A key part of the project will focus on expanding an existing structure-property database to improve machine learning and prediction. The project will begin with the synthesis of literature-reported gelators, aiming to obtain these structures via 'green' synthetic pathways. Using the chemistry acquired from the previous study, the project will then move toward the design of LMWGs from bio-based, waste, feedstocks such as terpenes, vanillin and macroalgae. Extensive testing of the properties of each gelator in different solvent systems and formulations will be carried out, comparing to polymer-based formulations. Rheological screening, spectroscopic imagery and toxicology studies will all be key components of this work.