Thermosensitive supramolecular and colloidal hydrogels via self-assembly modulated by hydrophobized cellulose nanocrystals
Thermosensitive supramolecular and colloidal hydrogels via self-assembly modulated by hydrophobized cellulose nanocrystals
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DOI：
10.1007/s10570-018-02225-8
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发表时间：
2019-01-01
期刊：
影响因子：
5.7
通讯作者：
Eichhorn, Stephen J.
中科院分区：
文献类型：
--
作者：
Nigmatullin, Rinat;Gabrielli, Valeria;Eichhorn, Stephen J.
利用可逆的非共价相互作用是开发刺激响应性软材料的一种通用设计策略。在这项研究中，利用疏水相互作用将水溶性大分子和纳米颗粒组装成一个瞬时杂化网络，形成具有可调流变性的热敏性水凝胶。杂化水凝胶是由生物聚合物衍生的成分：纤维素纳米晶(CNCS)、高纵横比纳米颗粒和羟丙基甲基纤维素(HPMC)构建的。为了能够通过疏水相互作用实现聚合物/碳纳米管的组装，对高亲水性碳纳米管的表面进行了辛基结合基团的修饰。表面张力测定证实了辛基碳纳米管的两亲性。分子和颗粒两亲分子组装成杂化网络，与HPMC水凝胶和亲水碳纳米管增强的水凝胶相比，形成了更坚硬和更坚固的水凝胶。杂化水凝胶保留了HPMC水凝胶在外加剪应力下流动的能力。然而，HPMC/辛基-CNCS水凝胶的粘度明显高于HPMC/CNCS水凝胶。由于温度通过疏水相互作用诱导聚合物/纳米粒子的缔合，HPMC水凝胶的流变性固有热响应与辛基碳纳米管结合被进一步放大。饱和传递差核磁共振谱表明，随着温度的升高，网络结合水的增长，这与水凝胶在受热时的硬度和粘度的增加有关。这些杂化水凝胶的流变性能由可溶聚合物和CNCS的含量来确定，并表明它们可以根据需要进行精细调整。
Utilization of reversible non-covalent interactions is a versatile design strategy for the development of stimuli responsive soft materials. In this study, hydrophobic interactions were harnessed to assemble water-soluble macromolecules and nanoparticles into a transient hybrid network forming thermosensitive hydrogels with tunable rheological properties. Hybrid hydrogels were built of biopolymer derived components: cellulose nanocrystals (CNCs), nanoparticles of high aspect ratio, and hydroxypropyl methylcellulose (HPMC). To enable polymer/CNC assembly via hydrophobic interactions, the surface of highly hydrophilic CNCs was modified by binding octyl moieties (octyl-CNCs). The amphiphilicity of octyl-CNCs was confirmed by surface tension measurements. The molecular and particulate amphiphiles assemble into hybrid networks, which result in stiffer and stronger hydrogels compared to HPMC hydrogels and hydrogels reinforced with hydrophilic CNCs. Hybrid hydrogels retain the ability of HPMC hydrogels to flow under applied shear stress. However, significantly higher viscosity was achieved for HPMC/octyl-CNCs compared with HPMC/CNCs hydrogels. The inherent thermal response of rheological properties of HPMC hydrogels was further amplified in combination with octyl-CNCs due to temperature-induced polymer/nanoparticle association via hydrophobic interactions. Saturation transfer difference NMR spectroscopy demonstrated the growth of network-bound water with an increase in temperature, which correlates with the increase of stiffness and viscosity of hydrogels upon heating. Rheological properties of these hybrid hydrogels are defined by the content of the soluble polymer and the CNCs, and it is shown that they can be finely adjusted for a required application.