以乙二醇、二甘醇、三甘醇、氯乙酰氯和N, N-二甲基十二烷基胺等为原料,经过两步反应合成了不同连接基链长的含酯基季铵盐Gemini表面活性剂C
12-E
2nO
m-C
12 (
n=1, 2, 3;
m=2, 3, 4),通过红外光谱(IR)、核磁氢谱(
1H NMR)、核磁碳谱(
13C NMR)和高分辨率质谱(HRMS)表征其结构,并对其表面张力、乳化性能、润湿性能、泡沫性能等进行了测试。结果表明,C
12-E
2O
2-C
12,C
12-E
4O
3-C
12和C
12-E
6O
4-C
12的临界胶束浓度(cmc)分别为0.815,0.152和0.044 2 mmol/L, 与十二烷基三甲基氯化铵DTAC (cmc值为10.25 mmol/L)相比要低1~2个数量级,且随着连接基链长的增加cmc值降低。C
12-E
2O
2-C
12,C
12-E
4O
3-C
12和C
12-E
6O
4-C
12的乳化分水时间分别为336,492和682 s,润湿时间分别为79,70和64 s,与DTAC (乳化分水时间和润湿时间分别为116和87 s)相比,C
12-E
2nO
m-C
12具有良好的乳化性能和润湿性能。进一步研究发现C
12-E
2nO
m-C
12具有优异的起泡和稳泡性能;且随着连接基链长的增长,其乳化、起泡、稳泡和润湿性能增强。
Three Gemini quaternary ammonium surfactants containing ester groups in spacers, C12-E2nOm-C12 (i.e., C12-E2O2-C12, C12-E4O3-C12 and C12-E6O4-C12), were synthesized via two-step reaction and characterized by IR, 1H NMR, 13C NMR and HRMS. The effects of spacer length on the self-aggregation, emulsifying, foaming and wetting properties of C12-E2nOm-C12 were investigated. Their corresponding monomer dodecyltrimethylammonium chloride (DTAC) was also investigated for comparison. The results showed that, the critical micelle concentration (cmc) values of C12-E2O2-C12, C12-E4O3-C12 and C12-E6O4-C12 were 0.815, 0.152 and 0.044 2 mmol/L, respectively, which were significantly lower than that of DTAC (10.25 mmol/L). Among these three Geminis, it was found that the cmc values of C12-E2nOm-C12 decreased with increasing spacer length. The phase separation time for evaluating the emulsifying abilities of C12-E2O2-C12, C12-E4O3-C12 and C12-E6O4-C12 were 336, 492 and 682 s, respectively; the wetting time of C12-E2O2-C12, C12-E4O3-C12 and C12-E6O4-C12 were 79, 70 and 64 s, respectively; therefore, C12-E2nOm-C12 exhibited excellent emulsifying and wetting properties compared with DTAC (the phase separation time was 116 s and the wetting time was 87 s). Moreover, C12-E2nOm-C12 also had better foaming ability and foam stability than DTAC. The emulsifying, foaming, foam-stabilizing and wetting abilities of C12-E2nOm-C12 were increased with the increase of spacer length.
