Water-Triggered Modulus Changes of Cellulose Nanofiber Nanocomposites with Hydrophobic Polymer Matrices
Water-Triggered Modulus Changes of Cellulose Nanofiber Nanocomposites with Hydrophobic Polymer Matrices
复制标题
DOI：
10.1021/ma300463y
复制
发表时间：
2012-06-12
期刊：
影响因子：
5.5
通讯作者：
Rowan, Stuart J.
中科院分区：
文献类型：
--
作者：
Dagnon, Koffi L.;Shanmuganathan, Kadhiravan;Rowan, Stuart J.
以聚苯乙烯-共丁二烯（SBR）或聚丁二烯（PBD）为疏水低模量基质，以从被囊动物（TW）中分离的亲水性纤维素晶须为高模量填料，制备了仿生、刺激响应的纳米复合材料。这些材料是用模板方法制备的，该方法包括形成一个渗透的TW网络，并用任意一种基质聚合物填充该模板。动态力学分析（DMA）研究表明，将TWs掺入橡胶聚合物中可以显著提高其拉伸存储模量E。这种增强是由于在SBR和PBD基体中形成了三维TW网络。TWs的掺入不影响基体SBR聚合物的主弛豫温度，表明纳米填料与聚合物的相互作用较弱。因此，增强主要是由于纳米填料与纳米填料之间的相互作用，其中涉及氢键。有趣的是，将这些疏水基质纳米复合材料浸入水中会导致剧烈的软化，这与由于氢键与水的竞争而导致的TW网络脱离一致。模量变化和吸水量的动力学与TW含量有关。考虑到基质的疏水性，我们提出TWs在疏水的SBR和PBD基质中创建了一个亲水通道的渗透网络。
Biomimetic, stimuli-responsive nanocomposites were made using either poly(styrene-co-butadiene) (SBR) or polybutadiene (PBD) as the hydrophobic, low-modulus matrix and hydrophilic cellulose whiskers isolated from tunicates (TW) as the high-modulus filler. These materials were prepared using a template approach, which involves the formation of a percolating TW network and filling this template with either of the matrix polymers. Dynamic mechanical analysis (DMA) studies of the dry nanocomposite films reveal that the incorporation of TWs into the rubbery polymers increases the tensile storage modulus E significantly. The reinforcement is attributed to the formation of a three-dimensional TW network within the SBR and PBD matrices. The incorporation of the TWs did not affect the main relaxation temperature of the matrix SBR polymer, suggesting weak nanofiller-polymer interactions. Thus, the reinforcement is primarily on account of the nanofiller-nanofiller interactions, which involve hydrogen bonding. Interestingly, submersion of these hydrophobic matrix nanocomposites in water results in dramatic softening, consistent with disengagement of the TW network as a consequence of competitive hydrogen bonding with water. The kinetics of the modulus change and the amount of water uptake were shown to depend on the TW content. Given the hydrophobic nature of the matrices, it is proposed that the TWs create a percolating network of hydrophilic channels within the hydrophobic SBR and PBD matrices.