Synthesis and properties of model - micronetworks

Microgels are small network particles with overall dimensions in the 100nm-region. Some experiments concerning the behaviour of cross-linked matter can be more easily performed using the molecular nature of μ-gels. In this publication, the synthesis and characterization by light and neutron scattering and dynamic-mechanical shear experiments of two different types of μ-gels are presented.

Diffusion coefficients D of singly and doubly end-labeled polystyrenes (PS) with molecular weights in the range 6500 ≤ M ≤ 75400 were measured in a PS matrix of molecular weight M′ = 111000, and in matrices with M′ = M. At 212°C, we find no influence of the label. In a power-law description D = D0 · M−α · M′−β we find α = 2,0 for M′ = 111000 and α + β = 2,4 for M = M′. The crossover to Rouse-like behavior for short-M chains is at Me ≈ 18000 for the former (high M′), and at Mc ≈ 33000 in the latter (M′ = M) case. At 185°C, we find a more complex scaling behavior and different D values for singly and doubly labeled PS.

Terminaison d'un polystyrene lineaire telechelique avec des anions aux deux extremites a l'aide d'un agent de terminaison bifonctionnel et une haute dilution