Investigating the UV-curing performance for polyacrylated polymer in dendritic and regular conformation

In this study, PDSC was employed to monitor the UV curing process for dendritic and regular monomers with various acrylate sites. Experimental results reveal that even with only a small increase in molecular weight for regular monomers caused a large increase in viscosity. A dendritic monomer with the same number of sites has a much lower viscosity. The conversion of hydroxyl groups into acrylic groups in the dendritic monomer slightly reduces the viscosity by destroying the hydrogen bonds. The curing conversion and curing rate increased with the number of acrylate sites to maxima at five. The acceleration of the double bond reaction within a dense group of multiacrylate sites is responsible for the initial rise, but the steric effect of the branches, hindering the simultaneous free-radical propagation, causes a decline as the number of sites increases in the curing of dendrimers. The autocatalyzed reaction model was then applied to simulate the curing results from PDSC. Dendrimers with 10-19 acrylate sites were found to have lower rate constant k and smaller autocatalyzed order m than the traditional ones. Finally, the heterogeneity of the cross-linking density of dendrimers generally causes dendritic monomers to have weaker hardness and lower T _d values than the regular ones. Nevertheless, dendrimers with 19 acrylate sites yield a film having low processing viscosity, satisfactory hardness (6H), reasonable T _d (290 °C), and a superior refractive index (1.5).