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ICI Research Fellow

Ph.D. Polytechnic University

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Dr. Dean Lee

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 development.

Dean is currently working with Dow Chemical in Michigan.


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