Recent studies on the solution properties of cellulose derivatives disclosed that two classes have to be distinguished, i.e. the fully and partially substituted chains. Molecularly dispersed solutions are obtained when all OH groups are substituted, while in the other case free OH groups cna undergo hydrogen-bonding resulting in association or aggregation. The measurements gave strong evidence for a non random aggregation that might result from uneven derivatization along the chain leading to blocks of low-substituted chain segments. A fringed micellar structure is concluded from the global properties of the aggregates. The model is confirmed and further specified by the angular dependence of the scattered light. The fringed micelle consists of a hard core of laterally aligned segments from which flexible chains emergy. The anisotropic hard core was confirmed by TEM and flow birefringence measurements. The flexibility of the dangling chains could be detected by dynamic light scattering. However, the flexibility became strongly reduced when the concentration was increased beyond the overlap concentration. This behavior results from the fact that the dangling chains cannot penetrate the hard core of the fringed micelle.
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