Tohyama K, Miller W G
Nature. 1981 Feb 26;289(5800):813-4. doi: 10.1038/289813a0.
The formation of a mechanically self-supporting, macromolecular gel or network is understood on a molecular scale in terms of cross-links or branch points, either of a permanent nature by covalent bond formation, or of a reversible nature, such as in the gelation of gelatin. In thermally reversible gels each branch point may contain numerous monomeric units, indicative of local crystallite or aggregate formation, as in cellulose acetate or gelatin, or only two monomeric units as in polyacrylylglycinamide. The formation of reversible networks in nonionic, rod-like polypeptide homopolymers, particularly at low concentrations (<0.1 wt%), is surprising in that the molecular origin of the branch points is not obvious. We have suggested previously that this network constitutes a thermodynamic phase resulting from a particular kinetic mechanism of phase formation made favourable by the unusual polymerdiluent phase equilibria occurring with stiff-chain polymers. Here, the network is visualized by electron microscopy, and shown to be compatible with the proposed mechanism.
在分子尺度上，机械自支撑的大分子凝胶或网络的形成可通过交联或分支点来理解，这些交联或分支点要么是通过共价键形成的永久性的，要么是可逆性的，比如明胶的凝胶化过程。在热可逆凝胶中，每个分支点可能包含大量单体单元，这表明存在局部微晶或聚集体的形成，如醋酸纤维素或明胶，或者像聚丙烯酰甘氨酰胺中那样仅包含两个单体单元。在非离子棒状多肽均聚物中，尤其是在低浓度（<0.1 wt%）下形成可逆网络，这令人惊讶，因为分支点的分子起源并不明显。我们之前曾提出，这种网络构成了一种热力学相，它是由特定的相形成动力学机制导致的，这种机制因刚性链聚合物所具有的不寻常的聚合物 - 稀释剂相平衡而变得有利。在此，通过电子显微镜观察到了该网络，并表明其与所提出的机制相符。
