CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China , Hefei, 230026, People's Republic of China.
Department of Chemistry, University of Tennessee , Knoxville, Tennessee 37996, United States.
Langmuir. 2017 Jun 20;33(24):6092-6101. doi: 10.1021/acs.langmuir.7b00972. Epub 2017 Jun 5.
Carbon nanotubes can be used as promising reinforcement materials to improve the mechanical properties of hydrogels, but their poor dispersibility in aqueous solution severely limits their application in preparation of composite hydrogels. Therefore, to develop method for modification of carbon nanotubes is still highly desired. In this paper, a facile approach for preparation of the hydrophilic carbon nanotube was reported. The encapsulated multiwalled carbon nanotubes (E-CNT-PAA) with cross-linked shell structure were obatined through the self-assembly of the amphipathic azide diblock copolymers poly(acrylic acid)-b-poly(4-vinylbenzyl azide-co-styrene) (PAA-b-(PVBA-co-PS)), and the cross-linking of inside azide groups under UV irradiation. The encapsulated MWCNT was characterized by FT-IR, Raman and TEM. It was demonstrated that the dispersibility of the hydrophilic encapsulated MWCNTs was related to the length of the poly(acrylic acid) brushes. Subsequently, thermal-responsive composite hydrogels (PNIPAM/E-CNT-PAA) were prepared by in situ polymerization of N-isopropylacrylamide (NIPAM) in the solution of dispersed E-CNT-PAA. The results showed that the composite hydrogels possessed high mechanical properties compared to the pure PNIPAM hydrogel. The tensile strength and elongation of the composite hydrogels were highly dependent on the content of the modified MWCNTs. The composite hydrogels with 0.46 wt % MWCNTs exhibited tensile strength of 97.7 kPa and elongation of 465%, which were at least 3.5× higher than those of the PNIPAM hydrogel. Moreover, the composite hydrogels displayed significant and reversible stimuli-responsiveness.
碳纳米管可用作有前途的增强材料来提高水凝胶的机械性能，但它们在水溶液中的分散性差严重限制了它们在复合水凝胶制备中的应用。因此，开发对碳纳米管进行改性的方法仍然是非常需要的。本文报道了一种制备亲水性碳纳米管的简单方法。通过两亲性叠氮嵌段共聚物聚（丙烯酸）-b-聚（4-乙烯基苄基叠氮-co-苯乙烯）（PAA-b-（PVBA-co-PS））的自组装和内部叠氮基团在紫外光照射下的交联，得到具有交联壳结构的包封多壁碳纳米管（E-CNT-PAA）。用 FT-IR、Raman 和 TEM 对包封的 MWCNT 进行了表征。结果表明，亲水性包封 MWCNT 的分散性与聚（丙烯酸）刷的长度有关。随后，通过 N-异丙基丙烯酰胺（NIPAM）在分散的 E-CNT-PAA 溶液中的原位聚合制备了温敏复合水凝胶（PNIPAM/E-CNT-PAA）。结果表明，与纯 PNIPAM 水凝胶相比，复合水凝胶具有较高的机械性能。复合水凝胶的拉伸强度和伸长率高度依赖于改性 MWCNT 的含量。含 0.46wt%MWCNT 的复合水凝胶的拉伸强度为 97.7kPa，伸长率为 465%，至少比 PNIPAM 水凝胶高 3.5 倍。此外，复合水凝胶表现出显著的和可逆的刺激响应性。
