Refreshing Rubbers as Customized Photothermal Conversion Materials through Post‐Darkening Modeling Production

Abstract

Organic conjugated polymers with low energy bandgaps are emerging as a particular class of near-infrared (NIR) photothermal conversion materials. However, these polymers routinely possess high phase transition temperatures due to the rigid skeleton and strong intermolecular interactions. Conjugated polymers can rarely be thermally processed at low temperature, especially below 100 °C. This work formulates a concept of post-darkening modeling production (p-DMP) by which the thermoplastic non-conjugated trans-polyisoprene (TPI) is refreshed into a photothermal conversion material with high light use efficiency. Two steps, including the customizable shaping at low temperature and iodine vapor-tailored "darkening", ensure the ease of preparing photothermal conversion devices with desirable topologies. A few characterizations, with the combination of density functional theory (DFT) calculations, provide reasonable explanations for understanding the "darkening" process of TPI in iodine atmosphere. In particular, the p-DMP is successfully extended to three-dimension (3D) printing, opening an avenue to fabricate personalized photothermal products, for example, a sunlight-directed physiotherapy device for healthcare of articular tissues.

Old inspires new: activation and stabilization of iodine in diene-based rubbers

“…The motivation started originally from the formulation of a processable photothermal dark material. 2 The photothermal materials developed focus mainly on carbon-based and metal-based materials and conjugated polymers. They are not preferable for additive manufacturing for customized production in terms of the rigidity in chemical structure or high melting point.…”

Radical Cation Initiated Surface Polymerization on Photothermal Rubber for Smart Antifouling Coatings

“…Previously, we have proposed a method for darkening trans ‐polyisoprene (TPI) as a kind of 3D‐printable photothermal materials by iodine doping . The study revealed that radical cations formed on TPI polymer backbones after the darkening treatment, which partially accounted for the wide absorption in visible‐ and near‐infrared‐light windows.…”

“…It is also convenient to locate the light energy in a targeting space without causing bulky interference . The photothermal conversion ability of iodine‐doped TPI, through which light energy could be converted to thermal heat, has been tested . In this regard, it is assumed that light irradiation may induce the “killing and releasing” strategy as the variation of temperature did.…”

“…Previously,w eh avep roposed am ethodf or darkening transpolyisoprene (TPI) as ak ind of 3D-printable photothermal materials by iodine doping. [14] The study revealed that radical cations formed on TPI polymer backbones after the darkening treatment, which partially accounted for the wide absorption in visible-and near-infrared-light windows. In conjunction with the exploitation of photothermal conversion materials,t his work presented the successful utilization of radicalc ationsa s initiators to trigger the scalablep olymerizationo ft hermosensitive PNIPAM on rubber surfaces.…”

“…[18] The photothermal conversion ability of iodinedoped TPI, through which light energy could be converted to thermalh eat, has been tested. [14] In this regard,i ti sa ssumed that light irradiation may induce the "killing and releasing" strategya st he variation of temperature did. As shown in Figure 4a-c, the surface temperature under astandard solar radiation was monitored by using an infrared camera.…”