Research ArticleAPPLIED SCIENCES AND ENGINEERING

3D printing of highly stretchable hydrogel with diverse UV curable polymers

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Science Advances  06 Jan 2021:
Vol. 7, no. 2, eaba4261
DOI: 10.1126/sciadv.aba4261
  • Fig. 1 Multimaterial 3D printing hydrogel with other polymers.

    (A) Illustration of the DLP-based multimaterial 3D printing apparatus. (B and C) Processes of printing elastomer and hydrogel structures, respectively. (D) Snapshot of a diagonally symmetric Kelvin form made of AP hydrogel and elastomer. (E) Demonstration of the high deformability of the printed diagonally symmetric Kelvin form. (F) Snapshot of a printed Kelvin foam consisting of rigid polymer, AP hydrogel, and elastomer. (G) Demonstration of the high stretchability of the printed multimaterial Kelvin foam. Scale bar, 5 mm. (Photo credit: Zhe Chen, Zhejiang University.)

  • Fig. 2 Materials and bonding mechanism.

    (A) Chemicals used to prepare the AP hydrogel solution. (B) Illustration of the water-soluble TPO nanoparticle. PVP, polyvinylpyrrolidone. (C) Possible chemical structure of the (meth)acrylate-based polymer solution. PI, photoinitiator. (D to G) Schematics of the process of printing hydrogel-polymer multimaterial structure. (H to J) Chemical structures of cross-linked AP hydrogel, AP hydrogel–(meth)acrylate polymer interface, and cross-linked (meth)acrylate polymer, respectively. R, R1, and R2 are the possible middle chains in (meth)acrylate polymer.

  • Fig. 3 Comparisons on polymerization conversion and bonding capability.

    (A) FTIR spectrums of AP hydrogels initiated by water-soluble TPO, I2959, and APS-TEMED, respectively. a.u., arbitrary units. (B) Comparison on photopolymerization kinetics of AP hydrogels initiated by TPO and I2959, respectively. (C) Comparison on the stress-stretch behavior of AP hydrogels initiated by TPO and APS-TEMED, respectively. (D and E) Demonstrations of bonding a UV curable elastomer to water-soluble TPO- and APS-TEMED–initiated hydrogel, respectively. (F and G) Uniaxial tensile tests of the dogbone samples printed with half AP hydrogel and half Tango elastomer (F), Vero rigid polymer (G), Agilus elastomer (H), PEGDA (I), methacrylate-based SMP (J), ABS-like polymer (K), respectively. (I to Q) Snapshots of the corresponding raptured samples. (Photo credit: Zhe Chen, Zhejiang University.)

  • Fig. 4 3D printed rigid polymer–reinforced hydrogel composites.

    (A to C) Hydrogel composite reinforced by horseshoe rigid polymer structure. (A) Isotropic picture of a printed composite. (B) Snapshots of the composite before uniaxial tensile test (left) and after stretched by 175% (right). (C) Comparison of the stress-strain behavior between pure hydrogel and composite. (D to F) Hydrogel composite reinforced by rigid polymer lattice structure. (D) Isotropic picture of a printed composite cube with gradient stiffness. (E) Front view of the printed composite cube where the diameter of truss rod decreases from 0.5 to 0.2 mm. (F) Measured compressive modulus for pure hydrogel and rigid polymer lattice structure–reinforced hydrogel with different rod diameters. (G) Snapshot of a printed meniscus made of hydrogel reinforced by rigid lattice structure. (H to K) The corresponding microscopic images of the microstructures at locations 1 to 4 within the printed meniscus (scale bars, 500 μm). (Photo credit: Zhe Chen, Zhejiang University.)

  • Fig. 5 Printed SMP stent with drug releasing function.

    (A) Illustration of the blood vessel expansion and drug releasing functions of the printed SMP-hydrogel stent. (B) Overall design of the SMP-hydrogel stent. (C) Detailed design shows that the SMP rod is surrounded the hydrogel skin loaded with drugs. (D) Illustration of the SMP-hydrogel programmed to a compacted shape. (E) DMA result indicates that the Tg of the SMP used to print the stent is 30°C. (F to H) Snapshots of printed SMP-hydrogel stents. (F) As-printed SMP-hydrogel stent. (G) SMP-hydrogel stent in programmed compacted shape. (H) SMP-hydrogel stents with different sizes. (I) Example to demonstrate both shape memory and drug releasing functions. (J) Quantified drug releasing process. Scale bar, 5 mm. (Photo credit: Jianxiang Cheng, Southern University of Science and Technology.)

  • Fig. 6 Printed soft pneumatic actuator with hydrogel strain sensor.

    (A) Schematic illustration of the SPA design. (B) Image of a printed SPA with hydrogel strain highlighted in pink color. (C) Experiments to investigate the resistance-stretch relation. (D) Bending sensor characterization. (E) Comparison between experiments and FEA simulations. (F) Relation between bending angle and measured strain on the sensor. (Photo credit: Zhe Chen, Zhejiang University.)

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