Harshdeep Bhatia

Title : Enhancing the surface properties of polymethylmethacrylate (Pmma) By functionalizing with atomic layer deposited titanium(Iv) Dioxide

Abstract:

Polymethyl methacrylate (PMMA) is a widely used polymer in applications such as engineering structural plastics, energy storage materials, and biomaterials. However, its poor surface properties lead to fracture and deformation. Functionalization of the PMMA surface can make it more resistant to aggressive environments and prevent it from biodegradation, discoloration, and increased surface roughness. Here, atomic layer deposition (ALD) was used to deposit TiO₂ thin films from tetrakis(dimethyl amido)titanium (TDMAT) and ozone on PMMA substrates to improve its surface properties without the need for plasma assistance or another interlayer. Spectroscopic ellipsometry was used for the first time to measure the metal oxide film thickness on thick PMMA substrates. Two different growth regimes were observed, one for the initial and the other for later ALD cycles. Initially, the growth rate on PMMA was 1.39 A ?/cycle, which is *3.5 times higher than that on stand-alone silicon (0.4 A ?/cycle); this is attributed to cyclic chemical vapor deposition of TDMAT and moisture within PMMA concomitant with TiO₂ ALD from TDMAT and ozone. However, after the formation of about 30-nm-thick film on PMMA, the TiO2 growth rate became similar to that on silicon. Moreover, our results revealed that the presence of PMMA in the deposition reactor affects the TiO₂ growth rate on silicon substrates as well. These findings are discussed and corroborated with residual gas analyzer and X-ray absorption near-edge structure data. The thermal stability of the PMMA samples was examined by thermogravimetric analysis. The chemical composition and surface roughness of coated PMMA were studied by X-ray photoelectron spectroscopy and optical profilometry, respectively. The TiO₂ coating increased wettability by ~ 70% and surface hardness by 60%.

Audience Take Away Notes:

• ALD of titania was successfully performed on PMMA, a popular biomaterial for the gum grafts of dental implants.
• Functionalization of PMMA is important to increase its biocompatibility and surface properties.  
• The discoveries in this research provide an outlook into the challenges faced when characterizing and functionalizing a porous substrate
• This research can be used to further functionalize other materials that are solvent sensitive and cannot be modified by other techniques like sol-gel methods.

Biography:

Mr. Harshdeep Bhatia completed his Bachelor of Technology in Chemical Engineering from Indraprastha University, New Delhi after which he joined a Ph.D. program at the University of Illinois, Chicago. Currently, his research is focused on the atomic layer deposition of metal oxides and metals on temperature-sensitive substrates for the applications of photocatalysis, optoelectronics, and antibacterial activity. His work has led to collaborations in the field of nanoelectronics and dental implants.