摘要
以木质素磺酸钠(LS)和1-溴十二烷为原料,吡啶为催化剂,在碱性醇水混合溶液中,利用超声波辅助烷基化反应制备生物基表面活性剂.通过GPC,UV,FTIR和1H-NMR对木质素磺酸钠及其直接烷基化产物(ALS)、超声烷基化产物(UALS)进行结构表征,结果表明超声活化使木质素磺酸钠的分子量从154200下降到106000,酚羟基的含量从0.65%提高到1.55%,活化效率达139%.1H-NMR谱中甲氧基的峰面积占总面积的比值由超声前的36.0%下降到超声后的21.0%.烷基化反应位点是LS的酚羟基,超声波活化烷基化效率明显高于直接烷基化效率.1%质量浓度的UALS的表面张力为28.2 mN/m,相同质量浓度的ALS和LS的表面张力分别为34.1 mN/m和41.5 mN/m.UALS的临界胶束浓度(CMC)是5×10-2g/L,比LS的低近两个数量级.超声烷基化效果较直接烷基化好的原因在于超声波处理一方面提高了酚羟基的含量,一方面破坏了大分子的三维网状结构,强化了体系的传质和传热效率.
In the presence of pyridine as a catalyst,a bio-based surfactant was synthesized via the alkylation of sodium lignosulfonate （LS） with 1-bromododecane in an alkalic isopropanol/water solution,with the aid of ultrasonic treatment.Structure and property characterization of sodium lignosulfonate （LS）,alkylated sodium lignosulfonate without ultrasonication （ALS） and alkylated sodium lignosulfonate with ultrasonication （UALS） were performed by GPC,UV,FTIR and 1H-NMR.The results showed that molecular weight of sodium lignosulfonate decreased from 154200 to 106000 after ultrasonic treatment while the phenolic content of sodium lignosulfonate increased from 0.65% to 1.55%.And the content of methoxy reduced from 36.0% to 21.0% at the same time.The results also showed that the alkylation of sodium lignosulfonate with the aid of ultrasonic treatment was more effective than that of without ultrasonic treatment.The alkylation of sodium lignosulfonate primarily occurred in phenol sites.As a result of the improvement of alkylation,surface activity analysis showed that surface tension of 1% aqueous solution of UALS decreased to 28.2 mN/m,by contrast to 34.1 mN/m of ALS and 41.5 mN/m of LS at the identical concentrations.Crucial micelle concentration of UALS was 5×10-2g/L,two orders lower than that of LS.Because hydrophobic group was effectively grafted to the macromolecule of sodium lignosulfonate under the influence of ultrasonication,UALS could hold a well-ordered molecular arrangement on the interface between the water and the air.Thus,it showed better surface activity than LS and ALS.And there were two possibly main reasons accounting for the enhancement of alkylating results with the assistance of ultrasonic treatment：on the one hand,it was ascribed to the generation of phenolic groups,and on the other hand,it was attributed to the cleavage of complicated molecular structures of sodium lignosulfonate under the influence of ultrasonication.
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
2013年第11期1363-1368,共6页
Acta Polymerica Sinica
基金
广东省中国科学院全面战略合作项目(项目号2011B090300067)资助
关键词
木质素磺酸钠
超声波
烷基化
结构表征
表面活性
Sodium lignosulfonate
Ultrasonic treatment
Alkylation
Characterization
Surface acitivity
