Branched copolymer surfactants impart thermoreversible gelation to LAPONITE® gels
Branched copolymer surfactants impart thermoreversible gelation to LAPONITE® gels
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支化共聚物表面活性剂赋予 LAPONITE® 凝胶热可逆凝胶作用
DOI：
10.1039/d3sm01271a
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发表时间：
2024
期刊：
影响因子：
3.4
通讯作者：
Rajbanshi A
中科院分区：
文献类型：
--
作者：
Rajbanshi A
本研究旨在将LAPONITE®粘土凝胶与热敏支链共聚物表面活性剂（BCSs）相结合，开发具有温度诱导溶胶-凝胶行为的先进功能材料。众所周知，各种各样的分子强烈地吸附在粘土上，可用于控制医疗保健应用中物种的解放，因此，聚合物/粘土混合材料的开发可以增加天然粘土行为的功能，这是非常有趣的。BCS的合成结构包括聚（乙二醇）甲基丙烯酸酯（PEGMA）、乙二醇二甲基丙烯酸酯（EGDMA）和十二烷基硫醇（DDT），具有通用和可调的热响应特性。系统调节单体：滴滴涕/引发剂的比例，以促进跨分子量范围的BCS结构的合成。通过小振幅振荡剪切（SAOS）流变学和小角度中子散射（SANS）结合可控温度变化，阐明了这些纳米复合材料的溶胶-凝胶转变动力学。通过利用SANS技术，利用对比匹配方法来减轻粘土和聚合物散射干扰，对这种转变和温度引起的成分变化的机制进行了补充分析。研究发现，在较低平均分子量（Mn）的凝胶成型样品中，从室温到室温的加热系统可诱导BCS在体水相中自组装，并伴有粘土的同步结构。SANS的研究对这一现象进行了解构，发现凝胶化发生在BCS在体中同时聚集的过程中，只有在低锰BCS体系中才会产生粘土-粘土的相互作用。
This investigation seeks to integrate LAPONITE® clay gels with thermoresponsive branched copolymer surfactants (BCSs) to develop advanced functional materials with temperature-induced sol–gel behaviour. It is known that a diverse range of molecules adsorb strongly to clays which may be used to control liberation of the species in healthcare applications, and as such the development of polymer/clay hybrid materials which can add function to the native clay behaviour are of great interest. BCS were synthesised with a structure that encompasses poly(ethylene glycol)methacrylate (PEGMA), ethylene glycol dimethacrylate (EGDMA), and dodecanethiol (DDT), conferring versatile and tuneable thermoresponsive attributes. Systematic modulation of the monomer : DDT/initiator ratio was used to facilitate the synthesis of BCS architectures spanning a range of molecular weights. Through application of small-amplitude oscillatory shear (SAOS) rheology and small-angle neutron scattering (SANS) in conjunction with controlled temperature variations, the sol–gel transition dynamics of these nanocomposite materials were elucidated. Complementary insights into the mechanisms underpinning this transition and temperature-induced alterations in the constituents are gleaned through the utilization of SANS techniques employing contrast-matching methodologies to mitigate clay and polymer scattering interference. It is found that heating systems from room- to body- temperature induces self-assembly of BCS in the bulk aqueous phase with concurrent structuration of clay in gel-forming samples with lower number average molecular weight (Mn). SANS study unpicks this phenomenon to find that gelation occurs with concurrent aggregation of BCS in the bulk, inducing clay–clay interactions only in lower Mn BCS systems with large nanoaggregates.