Study of variations in monomer conformations due to the presence of steric substituents is important as it provides insight into the relationship between surface structure and properties of monomers and polymers. Methacrylate monomers and their polymers are important because of their applications in dentistry, adhesives and lubricant coatings. Understanding the effect of variations in the interfacial conformation of the functionalized monomers will assist to the design of polymers used as polymer thin films. In this work, the ethyl end of the methacrylate backbone is substituted with methoxy (-OCH3), isopropoxy (-OiPr), tert-butoxy (-OtBu), and phenoxy (-OPh) groups to investigate the effect of steric substituents. These functionalized monomers are synthesized by the nucleophilic addition/elimination reaction between mathacryloyl chloride and the bulky substituted alcohol. Then these monomers are characterized using Sum Frequency Generation Spectroscopy (SFGS) at the air-liquid interface. The spectroscopic results are correlated with the measured surface tension (ST) values of the liquid monomers. The sterically substituted methacrylate-based functional monomers affect the contributions, distributions, and conformations of the molecular groups at the surface. The bulkier the substituent, an increase in the number density of the methyl symmetric stretch vibrational mode and their orientation towards the surface normal compete with the other molecular groups from orienting themselves at the interface. The ST values resulted in a trend where –OCH3&gt;-OiPr&gt;-OtBu agreed with the SFGS results. The –OPh substituted monomer had a high ST value due to the effect of existing dispersive forces including pi-bonding and its orientation at the surface.

Investigation of effect of steric substituents on the organization of methacrylate monomers at air-liquid interface using sum frequency generation spectroscopy

254th National Meeting (2017)

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