Shahin Allahbash, Nicolai Taco, Benyahia Lazhar, Tassin Jean-Francois, Chassenieux Christophe
LUNAM, Université du Maine , IMMM UMR CNRS 6283, PCI, 72085 Le Mans cedex 9, France.
Biomacromolecules. 2014 Jan 13;15(1):311-8. doi: 10.1021/bm401554s. Epub 2013 Dec 17.
Dynamic mechanical properties of aqueous solutions of hydroxypropyl methyl cellulose (HPMC) were investigated using oscillatory shear measurements. The structure was investigated with light scattering. A systematic investigation of the frequency dependence of the shear moduli showed that HPMC forms two distinct interpenetrating networks. A transient network is formed above about 0.3 wt % by reversible cross-linking of the chains. The elastic modulus of this network is independent of the temperature, but increases linearly with the concentration. An independent permanent network is formed involving a small fraction of the polymers and has an elastic modulus that increases with increasing temperature. Its elastic modulus is history dependent and evolves slowly with time. The transient network collapses at a critical temperature where micro phase separation occurs, but the permanent network is not influenced by this phenomenon. Light scattering showed that the pore size of the transient network is less than 40 nm, while probe diffusion measurements showed that the pore size of the permanent network is larger than 1 μm.
使用振荡剪切测量研究了羟丙基甲基纤维素（HPMC）水溶液的动态力学性能。通过光散射研究了其结构。对剪切模量频率依赖性的系统研究表明，HPMC形成了两个不同的互穿网络。通过链的可逆交联，在约0.3 wt%以上形成了一个瞬态网络。该网络的弹性模量与温度无关，但随浓度线性增加。形成了一个独立的永久网络，涉及一小部分聚合物，其弹性模量随温度升高而增加。其弹性模量与历史有关，并且随时间缓慢演变。瞬态网络在发生微相分离的临界温度下坍塌，但永久网络不受此现象影响。光散射表明，瞬态网络的孔径小于40 nm，而探针扩散测量表明，永久网络的孔径大于1μm。
