Preparation of a siloxane acrylic functional siloxane colloid for UV-curable organic-inorganic hybrid films

A new siloxane colloid was developed, for the use in UV-curable inorganic-organic hybrid films. The UV-crosslinkable silica-colloids were prepared from vinyltrimethoxysilane (VTMS) via a sol-gel method. The structure of silica-colloids was characterized using H-1 NMR, Si-29 NMR, Fr-IR, and matrix-assisted laser desorption/ionization (MALDI-TOF) mass spectrometry (MS). The particle size of the siloxane colloid was evaluated using atomic force microscopy (AFM) and small angle light scattering (SALS). Organic phase was based on an acrylated polyester which was synthesized using 1,4-cyclohexane dimethanol (1,4-CHDM), neopentyl glycol (NPG), 1,6-hexanediol (1,6-HD), maleic anhydride (MA), adipic acid (ADA), and acrylic acid (AA). The acrylated polyester was characterized by gel-permeation chromatography (GPC) and acid titration. A photo-initiator was added to the formulation and the UV-crosslinking reaction of hybrid film was monitored via photo-differential scanning calorimetry (Photo-DSC) and real-time infrared spectroscopy (RT-IR). The effect of the concentration of VTMS colloids, UV-light intensity, and exposure time on the polymerization rate was investigated and compared with an inorganic-organic hybrid film based on TEOS oligomers. Photo-DSC and RT-IR results indicated that VTMS colloids can greatly increase free radical polymerization rate and the VTMS colloids functioned effectively as cross-linker and reactive diluent. AFM and small angle light scattering (SALS) data showed that the silica-colloids were well dispersed in the organic phase.