Preparation and properties of UV‐curable poly(dimethylsiloxane) urethane acrylate. II. Property‐structure/molecular weight relationships

A series of UV‐curable polyurethane acrylate resins based on hydroxy‐terminated polydimethylsiloxane (PDMS) soft segments with different molecular weights and various diisocyanate hard segments were synthesized. The products were obtained by employing direct‐addition polymerization techniques in a nonsolvent system. The structures of the final products were elucidated by IR and 1H‐NMR. The fundamental and physical properties of this type of UV‐curable material, the effects on properties by varying the molecular weight of PDMS or the type of diisocyanates, and the effect of using various reactive diluents were widely studied. This resin possessed good optical, electrical insulating, and adhesive properties. The mechanical strength of UV‐cured films corresponds approximately to the ratio of hard segments within these material and the dielectric insulating properties correspond to the chain length of PDMS.