Optimized synthesis of highly reactive UV-curable hyperbranched polyester acrylates

Highly reactive radical polyester acrylates are widely used as UV-curing binder resins for printing inks, coatings, and materials for additive manufacturing. Especially for the latter, polyesters with low viscosities are of high interest, as they allow for UV-curing materials with reduced amounts of reactive diluents to adjust the viscosity. One possibility to obtain polyester acrylates with low viscosities is the synthesis of hyperbranched structures, as the interactions of the polymer chains are reduced in comparison to their linear counterparts. In this study, an optimized synthetic protocol is described to obtain a set of highly branched polyester acrylates with a high degree of acrylation, without the use of activated reagents like anhydrides or acid chlorides that are usually employed to synthesize these products. Different cores and number of pseudo-generations of 2,2-bis(hydroxymethyl)propionic (bisMPA) are utilized to study the structure-property relationship of this class of polyesters. Comprehensive characterization of the synthesized resins and cured materials revealed high reactivities and good mechanical properties compared to similar materials reported in the literature. The design of the structure significantly influences the properties, allowing for the synthesis of specific resins with a wide range of potential applications.