State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology , Beijing 100029, China.
Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology , Beijing 100029 P. R. China.
ACS Appl Mater Interfaces. 2017 Feb 22;9(7):6482-6487. doi: 10.1021/acsami.6b16308. Epub 2017 Feb 8.
Adaptive mechanical behaviors in nature have inspired the development of synthetic adaptive composites, with those responsive to water particularly relevant for biomedical applications. Polymer nanocomposites containing cellulose nanocrystals (CNCs) are prime examples of water-responsive mechanically adaptive materials. Although CNCs are biobased, the matrixes of these composites are exclusively petroleum-based synthetic elastomers, in sharp contrast to their biological counterparts. In this work, we attempted to probe the possibility of using bioderived rubber(s) as the matrix to fabricate CNC-nanocomposite with water-responsive adaptive mechanical behaviors. Specifically, natural rubber (NR) and epoxidized natural rubber (ENR) were used as the composite matrixes. Our results show that the water-responsive sensitivity and reversibility of ENR composites is much more drastic than that of NR composites. This is attributed to the strong CNC-polymer interaction (hydrogen bonding) for ENR, which leads to better filler dispersion and the formation of an extra CNC-polymer network in addition to the CNC-CNC filler network present in the NR composite. The synergistic effect of the dual networks plays a key role in tuning the mechanical properties and water-responsive sensitivity for various potential biomedical applications. Our study further provides guidance to make use of renewable resources to produce high value added water-responsive nanocomposites.
自然界中的自适应机械行为激发了合成自适应复合材料的发展，其中对水响应的复合材料尤其适用于生物医学应用。含有纤维素纳米晶体 (CNC) 的聚合物纳米复合材料是对水响应的机械自适应材料的典型例子。尽管 CNC 是基于生物的，但这些复合材料的基质完全是石油基合成弹性体，与它们的生物对应物形成鲜明对比。在这项工作中，我们试图探讨使用生物基橡胶作为基质来制备具有水响应自适应机械性能的 CNC 纳米复合材料的可能性。具体来说，天然橡胶 (NR) 和环氧化天然橡胶 (ENR) 被用作复合材料的基质。我们的结果表明，ENR 复合材料的水响应灵敏度和可逆性比 NR 复合材料剧烈得多。这归因于 ENR 中 CNC-聚合物的强相互作用（氢键），这导致更好的填料分散，并形成了除 NR 复合材料中存在的 CNC-CNC 填料网络之外的额外的 CNC-聚合物网络。双网络的协同效应在调节机械性能和水响应灵敏度方面发挥了关键作用，适用于各种潜在的生物医学应用。我们的研究进一步为利用可再生资源生产高附加值的水响应纳米复合材料提供了指导。
