Proton conductive copolymers by initiated Chemical Vapor Deposition

This project deals with the development of Proton Conductive Polymers (PCP) by initiated Chemical Vapor Deposition. PCPs are obtained by the combination of monomer units containing acid and hydrophobic groups. When immersed in water, the acid groups allow the passage of protons through the material, while the hydrophobic components ensure the integrity of the polymer backbone. PCPs are difficult to synthetize by conventional copolymerization methods because of the different solubility of the monomers. We propose to use the initiated Chemical Vapor Deposition (iCVD) to synthetize the PCP. iCVD is a dry polymerization method, which does not involve the use of solvents and therefore allows to easily copolymerize acid and hydrophobic monomers. The chemical structure of the PCPs can be finely tuned during the iCVD process, in order to obtain the best combination of proton conductivity and stability in a water solution. The proton transport in a hydrated PCP is speculated to occur through ionic channels which are interconnected hydrophilic clusters embedded inside the hydrophobic matrix. We propose to use x-ray based techniques to investigate the structure change upon immersion in water. The structural changes will be monitored before, during and after immersion in water. One extremely innovative aspect of the project is the use of X-ray reflectivity (XRR) and X-ray scattering to monitor the structural changes in the film, due to the water uptake, by using humidity controlled cells and temperature-controlled stage. Nowadays XRR is considered the most precise tool for thin film characterization. iCVD is a relatively new technique, invented at the Massachusetts Institute of Technology (MIT), and is not very widespread in Europe. The applicant intends to establish and enlarge the research on iCVD polymerization in Austria. An iCVD reactor is already available at the Graz University of Technology (TUGraz). This project foresees a close collaboration between MIT and TU Graz, which will certainly help creating an international network to spread iCVD knowledge, and relate it to the research already going on at the TUGraz.

In this project we worked on the development of Proton Conductive Polymers (PCP) by initiated Chemical Vapor Deposition. PCPs are used nowadays in fuel cells, as biopolymers and in electronic devices. They are obtained by the combination of monomer units containing acid and hydrophobic groups. When immersed in water, the acid groups allow the passage of protons through the material, while the hydrophobic components ensure the integrity of the polymer backbone. PCPs are difficult to synthetize by conventional copolymerization methods because of the different solubility of the monomers. We used an innovative vacuum-based method, called initiated Chemical Vapor Deposition (iCVD), to synthetize the PCP. iCVD does not involve the use of solvents and therefore allows to easily copolymerize acid and hydrophobic monomers. The chemical structure of the PCPs can be finely tuned during the iCVD process, in order to obtain the best combination of proton conductivity and stability in a water solution. The proton transport in a hydrated PCP is speculated to occur through ionic channels which are interconnected hydrophilic clusters embedded inside the hydrophobic matrix. We used x- ray based techniques to investigate the structure of the polymers. One extremely innovative aspect of the project is the use of X-ray reflectivity (XRR) and ellipsometry to monitor the structural changes in the film, due to the water uptake, by using humidity controlled cells and temperature-controlled stages. Nowadays XRR is considered the most precise tool for thin film characterization. iCVD is a relatively new technique, invented at the Massachusetts Institute of Technology (MIT), and is not very widespread in Europe. The PRO-CVD project allowed to establish and enlarge the research on iCVD polymerization in Austria. A part of the project was carried in collaboration between MIT and TU Graz, creating an international network that benefited all participants.