Surface Modification and Characterization of Polyester Amide Hyperbranched Polymer with 3-Mercapto Propyl Trimethoxy Silane from Sol-gel Method

In this investigation, a polyester-amide hyperbranched polymer possessing 10 hydroxyl end-groups was modified by 3-mercaptopropyle tri-methoxy silane through the well-known sol-gel chemistry. The modification process was carried out using two different independent variables, i.e. pH and duration of the reactions, at two and 4 various levels, respectively. The former's levels were 4.5 and 7 and the latter's levels were 0.5, 2, 8 and 24 hrs. To characterize the obtained products, Fourier transform infrared (FTIR) spectroscopy, Nuclear Magnetic Resonance (NMR) and Thermo-gravimetric analysis (TGA) were exploited. The outcomes demonstrated that the replacement of hydroxyl end-groups by mercapto functionalities had already happened. The samples at neutral pH, due to lower speed of hydrolysis reactions and higher speed of condensation ones, showed higher conversions. Among the assessed samples, the one at neutral pH and 8 hours of reaction duration, owed the maximum efficacy. Also, it was concluded that the longer the reaction duration, the higher the modification progress is obtained at both pH levels. Eventually, the optimum conditions for various kinds of modification levels are proposed.