Synthesis, Recycling and High‐Throughput Reprocessing of Phase‐Separated Vitrimer‐Thermoplastic Blends

Abstract

Phase‐separated polymer blends including a transesterification vitrimer and polypropylene are synthesized from widely available precursors through reactive processing. It is shown that proper formulation during the process including a viscosity modifier of the vitrimer precursors and a reactive interface compatibilizer yields well‐dispersed vitrimer phases with fractions up to 75 wt.% in the polypropylene phase. These vitrimer blends can be easily reprocessed by multiple shredding‐injection cycles and processed in high‐shear conditions through capillary rheometry. Rheological analyses reveal that a percolating dynamic network is formed across the vitrimer domains. It breaks apart during high shear reprocessing of the material and dynamically reforms after thermal annealing of the blends. It therefore ideally combines the mechanical and high‐throughput (re)processing properties of the thermoplastic matrix minor phase with the chemical, thermomechanical, and dynamic properties of the vitrimer major phase. This work illustrates the decoupling of processing at high shear rates enabled by the polypropylene processing aid from the kinetics of dynamic exchanges of the vitrimer phase and thermomechanical properties at the service temperature of the blends.

3D Printing of Vinylogous Urethane-Based Methacrylic Covalent Adaptable Networks by Vat Photopolymerization

“…13 An alternative route around this problem is to produce the vitrimer in situ during processing, such as the reactive extrusion approach of Qiu et al 14 and Li et al 15 for poly(ethylene terephthalate) and cellulose-based vitrimer, respectively, or the reactive blending system reported by Montarnal and co-workers. 16 Due to the challenges associated with the processing of CANs, the shape complexity of the final processed materials is generally limited, and therefore, new fabrication techniques to process CANs must be sought. In this sense, much of the effort has been focused on additive manufacturing (AM) technologies.…”

“…Similarly, Du Prez and co-workers reported the extrusion of vinylogous urethane-based associative networks by accelerating bond exchange through catalysis . An alternative route around this problem is to produce the vitrimer in situ during processing, such as the reactive extrusion approach of Qiu et al and Li et al for poly­(ethylene terephthalate) and cellulose-based vitrimer, respectively, or the reactive blending system reported by Montarnal and co-workers …”