Rapid energy-efficient manufacturing of polymers and composites via frontal polymerization

Abstract

Thermoset polymers and composite materials are integral to today's aerospace, automotive, marine and energy industries and will be vital to the next generation of lightweight, energy-efficient structures in these enterprises, owing to their excellent specific stiffness and strength, thermal stability and chemical resistance. The manufacture of high-performance thermoset components requires the monomer to be cured at high temperatures (around 180 °C) for several hours, under a combined external pressure and internal vacuum . Curing is generally accomplished using large autoclaves or ovens that scale in size with the component. Hence this traditional curing approach is slow, requires a large amount of energy and involves substantial capital investment. Frontal polymerization is a promising alternative curing strategy, in which a self-propagating exothermic reaction wave transforms liquid monomers to fully cured polymers. We report here the frontal polymerization of a high-performance thermoset polymer that allows the rapid fabrication of parts with microscale features, three-dimensional printed structures and carbon-fibre-reinforced polymer composites. Precise control of the polymerization kinetics at both ambient and elevated temperatures allows stable monomer solutions to transform into fully cured polymers within seconds, reducing energy requirements and cure times by several orders of magnitude compared with conventional oven or autoclave curing approaches. The resulting polymer and composite parts possess similar mechanical properties to those cured conventionally. This curing strategy greatly improves the efficiency of manufacturing of high-performance polymers and composites, and is widely applicable to many industries.

Advanced Polymer Designs for Direct‐Ink‐Write 3D Printing

“…Instead of using external stimuli to trigger the polymerization, White et al. introduced frontal polymerization to cross‐link monomers during DIW. Frontal polymerization is a self‐propagating exothermic reaction where the polymerization‐generated heat subsequently initiates the surrounding monomers .…”

“…Instead of using external stimuli to trigger the polymerization, White et al introduced [103] frontalp olymerizationt o cross-link monomers during DIW.F rontal polymerizationi sa self-propagating exothermic reaction where the polymerization-generated heats ubsequently initiatest he surrounding monomers. [104,105] The frontal-polymerization-based inki sc omposed of three key compounds:1 )a dicyclopentadiene as the monomer for ring-opening metathesis polymerization, 2) a second-generation Grubbs catalyst that can be thermally activated, and 3) an alkyl-phosphite inhibitor with optimized concentration to control the polymerization rate and subsequently the rheological profileo ft he ink.…”

Frontal polymerization accelerated by continuous conductive elements

“…Reactions involving heterogeneous materials are widely studied because of their unique reactivity and diverse applications including catalysis, surface coatings, and the fabrication of composite materials . The physical and chemical properties of compounds incorporated into heterogeneous materials dictate the overall reactivity in the system, as well as the properties of the product.…”

Stereolithographic 4D Bioprinting of Multiresponsive Architectures for Neural Engineering

“…We assume the laser‐induced graded internal stress, introduced through the printing process, is the major driving force of this 4D dynamic variation (Figure e). Internal‐stress‐induced volume shrinkage has been observed and studied in frontal photopolymerization where a polymer film is continuously cured by light from one side in a thick layer of liquid resin . By controlling light penetration, light intensity decreased along the sample thickness, inducing an intensity gradient in the resin .…”