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

项目背景（确定问题及其重要性和与可持续性的相关性）随着社会和环境压力的增加，沿着出台了控制微塑料释放到环境中的新法规;行业非常关注确保配方由易于生物降解的可持续材料制成。增稠剂是许多制剂的关键组分，然而它们通常由高分子量聚合物形成，例如聚（丙烯酸），其因其以非常低的重量百分比形成凝胶的能力而受到青睐。不幸的是，这些高分子量聚合物具有差的生物降解性，并且通常来源于石化产品，而生物基聚合物替代品，如羟乙基纤维素，是昂贵的并且需要大量提取。因此，产生了创造高分子量聚合物的替代品的挑战，所述高分子量聚合物是可生物降解的，在设计时考虑了可持续性，并且在相似的重量百分比下表现相同。 提出的解决方案和方法提出，通过设计具有通过超分子、非共价相互作用自组装的能力的低分子量结构（<2000 Da），可以形成具有与基于聚合物的系统类似的性质的凝胶。当低分子量胶凝剂（LMWG）与溶剂混合并施加刺激时，非共价相互作用（如氢键、π-π堆积或范德华力）可导致原纤维的形成，其缠结在一起并将溶剂分子截留在基质内形成凝胶。由于这些原纤维的骨架是非共价的，它们可以通过施加另一种物理或化学刺激而断裂，这可以根据废物处理的条件进行调整。主要挑战之一是设计能够在极性溶剂如水和丙二醇中形成凝胶的LMWG，作为个人护理制剂中的优选溶剂。溶剂的影响是复杂的，在这些系统中，因此在不同的溶剂系统中的胶凝剂的行为是难以预测的。该项目的一个关键部分将专注于扩展现有的结构-属性数据库，以改进机器学习和预测。该项目将开始与文献报道的凝胶因子的合成，旨在通过“绿色”合成途径获得这些结构。利用从以前的研究中获得的化学物质，该项目将转向从生物基废物，萜烯，香草醛和大型藻类等原料中设计LMWG。将对不同溶剂系统和配方中的每种胶凝剂的性能进行广泛测试，并与基于聚合物的配方进行比较。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.