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Neutron Reflectivity Study of Diblock Formation During Reactive Blending Processes.


pdf icon Neutron Reflectivity Study of Diblock Formation During Reactive Blending Processes. (399 K)
Hayashi, M.; Grull, H.; Esker, A. R.; Sung, L. P.; Satija, S.; Han, C. C.; Weber, M.; Hashimoto, T.

Macromolecules, Vol. 33, No. 17, 6485-6494, 2001.

Keywords:

polymer thin films; polymer blend films; diblock copolymer formation; neutron reflectivity

Abstract:

In a series of neutron reflectivity experiments, we studied the fundamental process of diblock formation during reactive blending processes of an immiscible blend comprised of normal polysulfone (hPSU) containing 30% reactive end group-modified deuterated polysulfone (dPSU-R) and polyamide (PA). Diblock formation (dPSU-b-PA) and dPSU-R enrichment at the interface between the incompatible polymers were monitored in thin bilayer films using neutron reflectivity. These results are compared to experimental results obtained with bilayer films of pure non-reactive deuterated PSU (dPSU) and PA and pure reactive dPSU-R and PA, respectively. The interfacial width in the pure reactive system is slightly larger than that in the pure non-reactive system, indicating the formation of a diblock copolymer at the interface of the reactive system. This study concludes that it is possible to diminish but not eliminate the interfacial tenxion ({gamma} > O) between the PSU and PA, as it is not possible to build up a large enough normalized surface excesses, z*/Rg < 1, of dPSU-b-PA.