| Popis: |
Gelation accompanying the crystallization from dilute and moderately dilute solution, which has been known to be characteristic of copolymers, is demonstrated to take place in homopolymers as well. The guiding principles by which to study this phenomenon are established. Carefully controlled experiments with both model homopolymers and copolymers are described in terms of these principles. Distinction must be made between homopolymers and copolymers as well as the thermodynamic nature of the solutions from which crystallization is occurring. For homopolymers covering a very wide molecular weight range, as well as for copolymers containing a surprisingly large co-unit content, the gels are found to be comprised of an overlapping supermolecular structure. The often postulated fringed micelle model for gel structure is only applicable, if at all, to copolymers of high co-unit content. |
