Design of silane-based UV-absorbing thin coatings on polyethylene films

Abstract

UV-absorbing surfaces have received much attention and focus due to their relevance in a variety of research applications and industrial fields. However, these surfaces currently suffer from drawbacks such as instability due to leakage of the entrapped UV-absorbing compounds, complicated non-green synthetic processes, and/or lack of good optical properties. We propose a modified Stöber method where UV absorbing silane monomers containing the group2-hydroxy-4-(3-triethoxysilylpropoxy) diphenylketone (SiUV) in presence of the mesoporous producing surfactant cetyltrimethyl ammonium chloride (CTAC) was polymerized in an ethanol/water continuous phase under basic conditions. UV absorbing thin coatings onto polyethylene (PE) films were then spread with the former dispersion on corona-treated PE, followed by a thermal drying process. These films were highly UV absorbent and durable with excellent optical properties. Multiple applications of the UV absorbing coating were also tested and found to increase UV absorbance to approximately 100%, but on the other hand the optical properties were negatively affected. The coated samples underwent thermal shrinkage by 30% to simulate industrial applications. No significant change in UV absorbance and optical properties were discerned after their shrinkage. These results and synthetic simplicity indicate to the potential of the SiUV coated polymeric films to be used for industrial applications.