Small-angle x-ray and neutron-scattering from bulk and oriented triblock copolymer gels
Mischenko, N × Reynders, K Koch, Mhj Mortensen, K Pedersen, Js Fontaine, F Graulus, R Reynaers, Harry #
Amer chemical soc
Macromolecules vol:28 issue:6 pages:2054-2062
Gels of polystyrene-block-rubber-block-polystyrene were investigated by small-angle X-ray (SAXS) and neutron (SANS) scattering. The rubber midblock was either poly(ethylene/propylene) (PS-PEP-PS) or poly(ethylene/butylene) (PS-PEB-PS). The gels of these thermoplasts have similar superstructures consisting of domains of associated polystyrene (PS) blocks, connected by the midblocks which are dissolved in an extender oil. The microphase separation is more pronounced in the PS-PEP-PS gels and results in clear interdomain scattering maxima and form factor oscillations. The ordering of the PS domains is a function of block copolymer concentration, molar mass, end block/midblock ratio, deformation, and temperature. Deformations up to 150% extension are reversible at room temperature. The scattering patterns of the unstretched samples were fitted with two different models: a hard-sphere liquid model and a model of a disordered solid with local coordination.