Rapid photothermal curing of PDMS on paper

Abstract

The desire for rapid curing of thermally-cured thermoset polymers directly on thermally-sensitive substrates, such as textiles, presents a dilemma: rapid curing requires high temperatures, but low temperatures are needed to preserve the properties of the substrate. In this manuscript, we test the ability of photothermal curing of polydimethylsiloxane (PDMS) bearing 0.5 wt% carbon black to cure PDMS on a thermally sensitive substrate (paper). Using differential scanning calorimetry and thermogravimetric analysis, we find that photothermal curing using ∼18 W cm⁻² of 808 nm light is able to cure PDMS on paper to the same extent as curing in a furnace at 200 °C, but in 1/60 the time. Furthermore, examining the color of the paper as well as its Young's modulus, toughness, and strength, we find that treatment in the oven changes these properties significantly, while photothermal curing leaves them statistically unchanged. In total, we demonstrate that photothermal heating is one way to realize curing of PDMS on thermally-sensitive substrates, while preserving the properties of the substrate.