Neutron Spin Echo Study of the Dynamics in BIS Cross-Linked Poly(N-Isopropyl Acrylamide) Microgels: Dependence on the Cross-Linker Concentration
Neutron spin echo spectroscopy (NSE) is an excellent tool to access the internal dynamics in gels and microgels. NSE directly provides the ensemble averaged intermediate scattering function 〈ISF〉E and due to the Q-range quasi-ergodic scattering behaviour is recovered. In the present study the cross-linker dependence of the internal dynamics of the gel network inside poly(N-isopropyl acrylamide) microgel particles was investigated by means of neutron spin-echo spectroscopy. The measured intermediate scattering functions are well described by single exponential decays, which is in agreement with the model derived by Tanaka et al. . The computed collective diffusion coefficients of the gel network decrease linearly with the number of cross-links introduced in the network for low cross-linker concentrations. This is in contrast with dynamic light scattering (DLS) results obtained for macroscopic gels based on the same polymer by Shibayama et al..
KeywordsDynamic Light Scat Relaxation Rate Dynamic Light Scattering Internal Dynamic Microgel Particle
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