Mrohs Tim B, Weichold Oliver
Institute of Building Materials Research, RWTH Aachen University, Schinkelstraße 3, 52062 Aachen, Germany.
Gels. 2022 Oct 19;8(10):669. doi: 10.3390/gels8100669.
The aim of this study was to evaluate the persistence of alkaline hydrogels based on a common (,'-methylenebisacrylamide, BIS) and three recently published tetraallyl crosslinkers. Such hydrogels have been shown to be suitable materials for the rehabilitation of cementitious materials. Of the four crosslinkers under investigation, ,,','-tetraallylpiperazinium dibromide decomposed quickly in 1 m KOH solution and was not considered further. BIS showed the first signs of a decomposition after several days, while tetraallylammonium bromide and ,,','-tetraallyltrimethylene dipiperidine dibromide remained unaffected. In contrast to BIS, which suffers from low solubility in water, the two tetraallyl crosslinkers show unlimited miscibility with diallyldimethylammonium hydroxide solutions. For the study, gels with up to 50 wt % crosslinker were prepared. Of these, gels containing tetraallylammonium bromide always show the highest degrees of swelling, with a peak value of 397 g/g at a content of 2 wt %. Under accelerated ageing at 60 °C for 28 d, gels crosslinked with BIS ultimately turned liquid, while the storage modulus and the degree of swelling of the two tetraallyl-crosslinked gels remained unchanged. This indicates that alkaline gels can be suitable for long application periods, which are common for rehabilitation measures in the construction industry.
本研究的目的是评估基于一种常见的（,'-亚甲基双丙烯酰胺，BIS）和三种最近发表的四烯丙基交联剂的碱性水凝胶的持久性。此类水凝胶已被证明是用于胶凝材料修复的合适材料。在所研究的四种交联剂中，,,','-四烯丙基哌嗪二溴化物在1 m KOH溶液中迅速分解，不再作进一步考虑。BIS在几天后出现了分解的最初迹象，而四烯丙基溴化铵和,,','-四烯丙基三亚甲基二哌啶二溴化物未受影响。与在水中溶解度低的BIS不同，这两种四烯丙基交联剂与二烯丙基二甲基氢氧化铵溶液无限混溶。为进行该研究，制备了交联剂含量高达50 wt%的水凝胶。其中，含有四烯丙基溴化铵的水凝胶总是表现出最高的溶胀度，在含量为2 wt%时峰值为397 g/g。在60°C加速老化28 d后，用BIS交联的水凝胶最终变成了液体，而两种四烯丙基交联水凝胶的储能模量和溶胀度保持不变。这表明碱性水凝胶可能适用于较长的应用期，这在建筑行业的修复措施中很常见。
