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首页> 外文期刊>RSC Advances >Biomass-based thermogelling copolymers consisting of lignin and grafted poly(N-isopropylacrylamide), poly(ethylene glycol), and poly(propylene glycol)
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Biomass-based thermogelling copolymers consisting of lignin and grafted poly(N-isopropylacrylamide), poly(ethylene glycol), and poly(propylene glycol)

机译：由木质素和接枝的聚（N-异丙基丙烯酰胺），聚（乙二醇）和聚（丙二醇）组成的基于生物质的热胶凝共聚物

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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 degrees 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.
机译：本文报道了使用原子转移自由基聚合（ATRP）技术合成和表征一系列基于生物质的热胶接枝共聚物，它们由木质素核心和接枝聚合物链的多臂组成，其中每个接枝均由一个嵌段组成。聚（N-异丙基丙烯酰胺）（PNIPAAm）和聚乙二醇（PEG）与聚丙二醇（PPG）的刷状无规嵌段共聚物。为了比较的目的，还合成了一些具有不同链结构和/或组成的对照共聚物。发现木质素基PNIPAAm-嵌段-PEG / PPG共聚物在水性介质中具有热响应性。共聚物的水溶液表现出热胶凝行为，从低温下的溶胶变成约32-34℃下的水凝胶，再到更高温度下变成脱水的凝胶。热胶凝共聚物的临界胶凝浓度非常低，为1.3至2.5重量％。研究了热响应流变性能。共聚物溶液的弹性模量G'和粘性模量G''在低温下非常低，而在较高温度下增加，然后在它们的胶凝温度下相交，在凝胶形成后，G'占主导地位。木质素基PNIPAAm-嵌段-PEG / PPG共聚物的结构对它们的水凝胶形成至关重要，因为具有相同单体比的木质素基PNIPAAm-无规-PEG / PPG共聚物作为对照聚合物无法在30℃形成水凝胶。任何温度，当温度升高时，溶液仅从透明变为浑浊。

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