My research interest is
to develop separation methods to characterize complex polymeric
materials. An effective separation method should be able to separate the
material based on the property we want to study. The retention time can
thus be used as a good evaluation of the material on this property. The
hyphenation of an absolute detector with
the separation unit can provide more information about the sample and
help to identify the non-idealities in the separation. The separation
method should be thus compatible to the absolute detector.
We developed a method
to use thermal field-flow fractionation (ThFFF) hyphenated with
multi-angle laser light scattering photometer (MALS) to characterize MW
distribution of microgels. Microgels are high MW components present in
paints, rubbers, and adhesives. ThFFF provides a non-gel based
separation which does not suffer from sample lost and degradation. The
hyphenation of the MALS to the ThFFF measured the mass of the
fractionated components, which overcame the non-ideal retention problem
encountered when dealing with complex samples.
We also developed a
method to characterize the trace impurities present in the non-ionic
surfactants. The column was overloaded in order to observe the trace
amount of the impurities. The impurities were eluted at near critical
condition. The identification of the impurities was successfully carried
out using MALDI/TOF to measure the accurate mass of the separated
components. The separated components yielded clean mass spectra, which
allowed elucidating the mass peaks without ambiguity.
We are currently
working on the separation of grafted copolymer . The goal is to be able
to characterize the grafting density distribution and/or chemical
composition distribution. A polymer gradient elution method is under
currently working with Dow Chemical in Michigan.