Polymers are important for several industrial applications such as coatings. The properties of polymers are affected by their chemical structure, and final bulk and interfacial conformations.Thus the goal of this project is to understand how modifying a specific end group of a monomer can affect the final conformation of a polymer using a more systematic approach.These physicochemical studies involved the synthesis and characterization of methacrylate-based functional monomers (MBFMs), polymers, and polymer thin films (PTFs) using SFGS and AFM. In general, the MBFMs were modified via replacement of the functional group at the ethyl end of the monomer.First, the effect of electronic and steric substituents on these monomers was studied at the air-liquid (AL) interface using SFGS.The molecular conformational change at the interface was monitored by acquiring SFG spectra at different polarization combinations.A key observation was the presence of the peak positioned at 3000 cm-1.This peak was assigned to the alkene-methylene (=CH2) CH stretch.The presence of the =CH2 can indicate the completeness of the polymerization.Also, the spectral results allowed the estimation of the orientation of the methyl (CH3) symmetric stretch positioned at ~2900 cm-1 in the CH region.Specifically, the tilt angle of the CH3 group of the 2-methoxyethyl methacrylate (MEMA) monomer was estimated using polarization combination and polarization mapping methods.The spectral results and orientational analysis showed that the MEMA monomer is partially-ordered at the air-monomer interface.The steric substituents of the MBFMs were also investigated at the monomer-hydrophilic quartz interface to verify the conformations of these monomers in a much controlled environment.The spectral profile and results at this interface are different from the AL interface using the same MBFMs.The C=O group was only observed at the monomer-hydrophilic quartz interface.Lastly, the polymer thin films of MBFMs were prepared via spin coating of polymer solutions.The study involved changing the solvents and annealing times. The PTFs were characterized using AFM and SFGS. Correlation of AFM and SFG results are significant in the interpretation of the actual interactions and the overall conformation of the polymers at the air-polymer interface.To mention, the valuable information that was obtained in these studies will help polymer chemists design polymers for more effective coatings and inhibitors.

Investigation of functional monomers, polymers, and polymer thin films using sum frequency generation spectroscopy (SFGS) and atomic force microscopy (AFM)

254th National Meeting (2017)

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