Speaker
Description
Shape memory polymers (SMPs) are a class of smart materials capable of undergoing programmed shape changes in response to external stimuli. Polyglycerol dodecanoate acrylate (PGDA), a thermally responsive SMP, has demonstrated promise in biomedical applications due to its biocompatibility.[1] However, its high viscosity and the requirement for harsh thermal curing hinder its use in vat-based 4D printing. Additionally, the dense, nonporous nature of PGDA limits cell infiltration, posing a challenge for tissue engineering. In this study, we formulated novel ink for 4D printing using a mixture of PGDA, polyglycerol sebacate acrylate (PGSA), and polyethylene glycol (PEG). PEG functions as a porogen to induce porosity and as a rheological modifier. PGSA, structurally differing from PGDA by a two-carbon-shorter dicarboxylic acid, offers a lower melting point, facilitating processing.
PGDA and PGSA were synthesized following established protocols.[2,3] Equimolar amounts of glycerol and dodecanedioic or sebacic acid were reacted under nitrogen for 24 hours. Acrylation was performed by dissolving 20 g of prepolymer in a basic solution (methoxyphenol, 4-dimethylaminopyridine, triethylamine, and methylene dichloride), followed by the dropwise addition of acryloyl chloride under inert conditions for 24 hours. The reaction mixture was purified via rotary evaporation and ethyl acetate washing. PGDA and PGSA were then blended at ratios of 3:1, 1:1, and 1:3 with 0–30 wt.% PEG at 60°C. The rheological measurements were carried out using a TA Instruments HR20 rheometer with a 100 µm gap, in triplicate for each study group. Rectangular shape (3×5×3) 3D-printed using Cellink Lumen X Gen3 with 20mW.cm-2 UV intensity and 10 seconds exposure for 100 µm layers. The PEG leached out from the samples, programmed at 37ºC and fixed at 0ºC before the shape memory behavior test.
The rheological measurements showed a decrease in the viscosity of PGDA with the addition of 15 and 30 wt% PEG at 40ºC (Figure 1A). Additionally, the incorporation of PGSA by 3-fold resulted in a lower viscosity at 40ºC (Figure 1B). Adding PEG to the 3:1 group further decreased the viscosity to reach the printable region. A similar trend was also observed using 1:1 and 1:3 ratios of PGDA:PGSA to achieve more printable resins (Figure 1C and 1D). The 3:1 formulation with 30 wt.% PEG was used to 3D print SMP strips, which showed shape memory behavior upon exposure to 37ºC water (Figure 2). Future studies will focus on characterizing the porosity percentage, the pore size, and the degradability behavior of the printed structure.
References
[1] L. Wang, K. Jin, N. Li, P. Xu, H. Yuan, H. Ramaraju, S. J. Hollister, Y. Fan, Nat Commun 2023, 14, 3865.
[2] C. Zhang, D. Cai, P. Liao, J.-W. Su, H. Deng, B. Vardhanabhuti, B. D. Ulery, S.-Y. Chen, J. Lin, Acta Biomaterialia 2021, 122, 101.
[3] R. Qu, D. Zhou, T. Guo, W. He, C. Cui, Y. Zhou, Y. Zhang, Z. Tang, X. Zhang, Q. Wang, T. Wang, Y. Zhang, Materials & Design 2023, 225, 111556.
74734106004
