Mariani Giacomo, Colard-Itté Jean-Rémy, Moulin Emilie, Giuseppone Nicolas, Buhler Eric
Matière et Systèmes Complexes Laboratory (MSC), UMR CNRS 7057, Université de Paris, Bâtiment Condorcet, 75205 Paris Cedex 13, France.
Institut Charles Sadron, UPR CNRS 22, Université de Strasbourg, 23 rue du Loess, BP 84047, 67034 Strasbourg Cedex 2, France.
Soft Matter. 2020 Apr 29;16(16):4008-4023. doi: 10.1039/d0sm00031k.
The detailed structure of active polymer gels built by integrating light-driven rotary molecular motors as reticulation units in polymer networks is discussed as a function of gel composition. Upon light-irradiation, the collective rotation of molecular motors is translated into the macroscopic contraction of the gels through polymer chains twisting. The major role of the characteristic ratio c/c* (c* being the overlap concentration of the polymer-motor conjugates before crosslinking) on the contraction efficiency is exploited. Combined small-angle neutron and X-ray scattering experiments reveal the importance of heterogeneities in the macroscopic contraction process: the mesh size of the network increases under irradiation in the whole range of c/c*, an increase that is maximal for c/c* = 1; i.e. at higher contraction efficiency. Furthermore, the mesh size of the network reaches equilibrium within a short period of time, while the heterogeneities increase in size untill the end of the contraction process. Finally, the significant motorized twisting of polymer chains within the network allows to foresee the design of new storage energy systems.
本文讨论了通过将光驱动旋转分子马达作为聚合物网络中的网状单元构建的活性聚合物凝胶的详细结构与凝胶组成的关系。光照后，分子马达的集体旋转通过聚合物链的扭曲转化为凝胶的宏观收缩。研究了特征比c/c*（c为交联前聚合物-马达共轭物的重叠浓度）对收缩效率的主要作用。小角中子散射和X射线散射联合实验揭示了宏观收缩过程中不均匀性的重要性：在整个c/c范围内，光照下网络的网孔尺寸增大，在c/c* = 1时增大最大，即收缩效率更高时。此外，网络的网孔尺寸在短时间内达到平衡，而不均匀性的尺寸一直增加到收缩过程结束。最后，网络内聚合物链的显著电动扭曲有助于预见新型储能系统的设计。
