Photocrosslinked reprocessable hydrogenated nitrile butadiene rubber with dynamic hindered urea bonds for sustainable DLP 3D printing

A photocrosslinkable and dynamically rearrangeable HNBR elastomer with HUBs was prepared. • The mechanical performance of photo-cured HNBR is comparable to that of DCP-vulcanized HNBR. • The photo-cured HNBR exhibits recyclability with a self-healing efficiency of nearly 90%. • Modular printing was employed to fabricate intricate components. • High-resolution 3D reprinting of HNBR retaining excellent thermal and oil resistance was achieved. To address the high energy consumption and limited recyclability of conventional sulfur and dicumyl peroxide (DCP)-vulcanization of hydrogenated nitrile butadiene rubber (HNBR), this study developed a photocrosslinkable and dynamically rearrangeable HNBR-based elastomer for digital light processing (DLP) 3D printing. A photocurable prepolymer, denoted as HNBRPU, was synthesized from hydroxyl-terminated liquid HNBR (HHTBN) and functionalized with dynamic hindered urea bonds (HUBs) and terminal photopolymerizable C C bonds. Rapid photocuring of HNBRPU-5.0 under 405 nm UV light yields crosslinked HNBR elastomers with superior mechanical performance, including a tensile strength of 13.8 MPa and a toughness of 28.3 MJ/m 3 , values comparable to those of conventionally DCP-vulcanized HNBR. The thermally reversible HUBs endow the material with reprocessability, achieving a self-healing and recycling efficiency of nearly 90%. By formulating HNBRPU with reactive diluent isobornyl acrylate (IBOA), high-resolution DLP 3D printing of complex geometries was achieved. A modular printing strategy was further developed to facilitate the fabrication of sophisticated structural components. The printed object can be fully dissolved in 2-(tert-butylamino) ethyl methacrylate (TBEM) at 90 °C within 4 h and blended with 20 wt% fresh HNBRPU/IBOA resin for reprinting, without sacrificing thermal stability or oil resistance. This work provides a sustainable and efficient strategy for fabricating reprocessable 3D-printable elastomers and is generalizable to other 3D printing systems based on dynamic covalent chemistry. Download: Download high-res image (207KB) Download: Download full-size image