Department of Chemistry, University of Warwick, Gibbet Hill Road, CV4 7AL, Coventry, UK.
J Mater Chem B. 2021 Jan 28;9(3):809-823. doi: 10.1039/d0tb02390f.
The application of functional self-healing and mechanically robust hydrogels in bioengineering, drug delivery, soft robotics, etc., is continuously growing. However, fabricating hydrogels that simultaneously possess good mechanical and self-healing properties remains a challenge. Developing robust hydrogel formulations for the encapsulation and release of hydrophobic substances is a major challenge especially in some pharmaceutical treatments where the many of drugs show incompatibility with the hydrophilic hydrogel matrices. Schiff base hydrogels have been developed using a benzaldehyde multifunctional amphiphilic polyacrylamide crosslinker in conjunction with glycol chitosan. The polymeric crosslinker was synthesized by a two-step reaction using aqueous Cu-RDRP to give an ABA telechelic copolymer of N,N-dimethyl acrylamide (DMAc) and N-hydroxyethyl acrylamide (HEAm) from a bifunctional PEG. The polymer was then modified by post functionalization leading to a multifunctional benzaldehyde crosslinker that was shown to be capable of self-assembly into aggregates in aqueous media serving as a possible candidate for the entrapment of hydrophobic substances. Aqueous solutions of the crosslinker spontaneously formed hydrogels when mixed with glycol chitosan due to the in situ formation of imine bonds. Hydrogels were characterized while additional comparisons were made with a commonly used bifunctional PEG crosslinker. The effect of introducing partially reduced graphene oxide (GO) nanosheets was also examined and led to enhancements in both mechanical properties (2.0 fold increase in modulus and 1.4 fold increase in strain) and self-healing efficiencies (>99% from 60% by rheology) relative to the pristine polymer hydrogels.
应用功能自修复和机械坚固的水凝胶在生物工程、药物输送、软机器人等领域不断发展。然而，制造同时具有良好机械性能和自修复性能的水凝胶仍然是一个挑战。开发用于封装和释放疏水性物质的坚固水凝胶配方是一个主要挑战，特别是在一些药物治疗中，许多药物与亲水性水凝胶基质不相容。席夫碱水凝胶是使用多功能苯甲醛两亲性聚丙烯酰胺交联剂与乙二醇壳聚糖联合开发的。通过两步反应使用水性 Cu-RDRP 合成了聚合物交联剂，从双功能 PEG 中得到 N，N-二甲基丙烯酰胺（DMAc）和 N-羟乙基丙烯酰胺（HEAm）的 ABA 遥爪共聚物。然后通过后功能化对聚合物进行修饰，得到多功能苯甲醛交联剂，该交联剂能够在水介质中自组装成聚集体，可用作疏水物质的包埋的候选物。由于亚胺键的原位形成，当交联剂与乙二醇壳聚糖混合时，水相溶液会自发形成水凝胶。对水凝胶进行了表征，并与常用的双功能 PEG 交联剂进行了额外的比较。还研究了引入部分还原氧化石墨烯（GO）纳米片的效果，与原始聚合物水凝胶相比，机械性能（模量增加 2 倍，应变增加 1.4 倍）和自修复效率（流变学上从 60%提高到>99%）都得到了提高。
