共聚物
乙二醇
高分子化学
聚合物
材料科学
原子转移自由基聚合
水溶液
自愈水凝胶
化学工程
聚合
PEG比率
低临界溶液温度
单体
化学
有机化学
复合材料
经济
工程类
财务
作者
Bishuo Diao,Zhongxing Zhang,Jingling Zhu,Jun Li
出处
期刊:RSC Advances
[The Royal Society of Chemistry]
日期:2014-09-11
卷期号:4 (81): 42996-43003
被引量:46
摘要
This paper reports the synthesis and characterization of a series of biomass-based thermogelling graft copolymers using atom transfer radical polymerization (ATRP) technique, which are composed of a lignin core and multiple arms of graft polymer chains, where each graft consists of a block of poly(N-isopropylacrylamide) (PNIPAAm) and a block of brush-like random copolymer of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG). A few control copolymers with different chain architectures and/or compositions were also synthesized for comparison purposes. It was found that the lignin-based PNIPAAm-block-PEG/PPG copolymers were thermo-responsive in aqueous medium. The aqueous solutions of the copolymers displayed thermogelling behaviors, turning from a sol at low temperatures to a hydrogel at temperatures around 32–34 °C, and further to a dehydrated gel at higher temperatures. The thermogelling copolymers had very low critical gelation concentrations ranging from 1.3 to 2.5 wt%. The thermo-responsive rheological properties were investigated. The elastic modulus G′ and viscous modulus G′′ of the copolymer solutions were very low at low temperatures, and increased at higher temperatures, and then crossed over at their gelation temperatures, with G′ dominating G′′ after the gel formation. The block architecture of the lignin-based PNIPAAm-block-PEG/PPG copolymers is key to their hydrogel formation, because the lignin-based PNIPAAm-random-PEG/PPG copolymer with the same monomer ratio, as a control polymer, could not form hydrogels at any temperature, whose solution only turned from transparent to turbid when the temperature was increased.
科研通智能强力驱动
Strongly Powered by AbleSci AI