Vat Photopolymerization of Reinforced Styrene–Butadiene Elastomers: A Degradable Scaffold Approach

Abstract

Vat photopolymerization (VP) is a high-throughput additive manufacturing modality that also offers exceptional feature resolution and surface finish; however, the process is constrained by a limited selection of processable photocurable resins. Low resin viscosity (<10 Pa·s) is one of the most stringent process-induced constraints on resin processability, which in turn limits the mechanical performance of printed resin systems. Recently, the authors created a VP-processable photosensitive latex resin, where compartmentalization of the high molecular weight polymer chains into discrete particles resulted in the decoupling of viscosity from molecular weight. However, the monomers used to form the hydrogel green body resulted in decreased ultimate material properties due to the high cross-link density. Herein, we report a novel scaffold that allows for facile UV-based AM and simultaneously enhances the final part’s material properties. This is achieved with a chemically labile acetal-containing cross-linker in conjunction with N-vinylpyrrolidone, which forms a glassy polymer after photocuring. Subsequent reactive extraction cleaves the cross-links and liberates the glassy polymer, which provides mechanical reinforcement of the geometrically complex VP-printed elastomer. With only a 0.1 wt % loading of photoinitiator, G′/G′′ crossover times of less than 1 s and green body plateau moduli nearing 105 Pa are obtained. In addition, removal of the hydrophilic and thermally labile scaffold results in decreased water uptake and increased thermal stability of the final printed part. Ultimate strain and stress values of over 650% and 8.5 MPa, respectively, are achieved, setting a new benchmark for styrene–butadiene VP elastomers.

Multifunctional Medical Grade Resin with Enhanced Mechanical and Antibacterial Properties: The Effect of Copper Nano-Inclusions in Vat Polymerization (VPP) Additive Manufacturing

“…Each compound was stirred in a high rotational/shear stirrer to ensure the homogeneous dispersion of the Cu nanoparticles in the biomedical resin, i.e., to produce a grade consistent suspension for both the 0.5 wt.% and 1.0 wt.% filler concentrations. The process followed for the preparation of the nanocomposites is compatible with the literature for the preparation of composites for the VPP process [ 106 , 107 , 108 ].…”

Additive Manufacturing of Polymer‐Based Lubrication

“…Reproduced with permission. [96] Copyright 2022, American Chemical Society, and b) Schematic of the preparation of PVA-BA/PEG hydrogel and a tensile stress-strain curve. Reproduced with permission.…”

“…of surface-attached hydrogels: the adhesion between the sliding layers and the deformation brought on by the gel compression by the applied normal force under sliding conditions. Kasprzak et al, [96] developed a VP-processable photosensitive latex resin in which high-molecular-weight polymer chains are broken into discrete particles, resulting in a decoupling of viscosity from the molecular weight (Figure 12a). However, the final properties of the material are reduced due to the high crosslinking density of the monomers used to form the green hydrogel parts.…”

“…Scheme a) photographic flowchart of a vat photopolymerized print subject composed and reactive of particles;The extraction process demonstrates the retention of geometric complexity; Photorheological profiles of photocurable latex formulations with variable cross-linker concentrations: Stress-strain profiles of elastomeric materials subjected to successively increasing strains; pure latex, reactively extracted VP material. Reproduced with permission [96]. Copyright 2022, American Chemical Society, and b) Schematic of the preparation of PVA-BA/PEG hydrogel and a tensile stress-strain curve.…”

Binary Thiol-Acrylate Photopolymerization for the Design of Degradable Acetal-Functionalized Hydrogels

“…Mild and selective hydrolysis renders the acetal as an attractive functionality for predictive network degradation. Recently, our research group replaced PEG diacrylate crosslinkers with acetal-functionalized diacrylate analogues as scaffolds for 3D printing elastomers after selective degradation and removal of the crosslinked scaffold . Our prior work warranted further investigation of acetal- and acrylate-containing networks for potential delivery vehicles with tunable release rates.…”