Small angle neutron scattering (SANS) is a powerful method for probing properties of complex polymeric material systems. It is unique in that contrast between polymer chains can be induced by labeling target chains with deuterium. Examination of single chain behavior in bulk is thus possible. A hydrogen-deuterium exchange reaction can be used for labeling fully saturated polyolefins, regardless of the synthetic history of the materials. This method appears to depend on the solvents and polymer architecture used. We are interested in the following aspects of this H/D exchange mechanism: 1) what impacts distribution of deuterium among deuterated chains; 2) how do these deuterated chains mix with hydrogenous chains, and phase stability of their blends. A series of commercial linear low density polyethylenes (LLDPE) as well as model polyethylenes(PE) synthesized with anionic polymerization technique were used in this work. We found that the deuteration level of these LLDPEs is dependent on branching and molecular weight of the polyolefin used. For deuterated polydisperse commercial LLDPEs, size exclusion chromatography (SEC) combined with infrared (IR) method can be used to quantify deuteration heterogeneity among different molecular weight or microstructure fractions. These results will be related to the observed SANS results. Further application of this exchange mechanism includes determining single chain deformation behavior during processing using an in-situ tensile-SANS method.

Mechanism and application of selective hydrogen-deuterium exchange reaction for saturated polyolefins

251st National Meeting (2016)

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