Non-self-similar aggregation of methylcellulose

Aggregation of methylcellulose in aqueous dilute solution is studied by lig ht and small angle neutron scattering. For temperature T< 293.15K, the free chains adopt a swollen conformation. For T> 313.15K, a slow aggregation ki netics occurs. At qR(g) <1, the association number is found to vary as R-g( 3). However at qR(g)>1, the scattered intensity decreases as q(-(1<d less t han or equal to 1.3)) depending on the temperature. At even higher q, one o bserves a local compaction as aggregation proceeds, as revealed by a more a nd more pronounced Porod's behaviour. Results are discussed in terms of non selfsimilar growing aggregates, having neither a rod-like nor a dense stru cture.