Dynamic light scattering study of a 1,4-isoprene-b-styrene copolymer
Local optical anisotropy fluctuations within polystyrene (PS)-rich region in a disordered 1,4-isoprene-b-styrene (PI-b-PS) copolymer with XN≈5.3 (N=44) and glass transition temperature T g=13°C were analyzed by photon correlation spectroscopy (PCS) over a broad time range (10−7−103 s). There is strong experimental evidence that composition fluctuations in the present system can affect the segmental orientational fluctuations of the two foreign blocks. The significant broadening of the distribution of orientation times with decreasing temperature toward T g can be rationalized in terms of the coupling scheme of relaxation.
Key wordsDiblock copolymers dynamic light scattering concentration fluctuations coupling model
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