Giving green polymers the blue light

BLUE light has been used by researchers to create an interpenetrating polymeric network (IPN) in one step, under ambient conditions.

When linked together, two or more polymer chains with different mechanical properties can form IPNs. This resulting network is not bonded through chemical means, instead polymer chains are entangled and cannot be pulled apart. Subsequently, material performance can be enhanced, with applications including ion exchange resins and medical dressings. However, the process of linkage typically requires a lengthy two-step process or a one-step process requiring high temperatures.

Now, researchers at the University of Delaware, US, have reported in Polymer Chemistry a novel one-step process to produce an IPN. The new network exhibited enhanced toughness, and overcame issues of brittleness without any solvents or additives, making it a greener synthetic approach.

Their method involves using 470 nm blue light to photoinitiate the formation of two networks simultaneously and orthogonally, which occurs at room temperature in air. One reaction was copper-catalysed azide-alkyne cycloaddition (CuAAC) click polymerisation. This reaction is facilitated by copper, and polymerisation occurs in steps. The other was methacrylate polymerisation, which forms a plastic-like material in a manner similar to adding links to a growing chain.