Crystallization-Induced Gelling as a Method to 4D Print Low-Water-Content Non-isocyanate Polyurethane Hydrogels

Abstract

The use of three-dimensional (3D) printable hydrogels for biomedical applications has attracted considerable attention as a consequence of the ability to precisely define the morphology of the printed object, allowing patients’ needs to be targeted. However, the majority of hydrogels do not possess suitable mechanical properties to fulfill an adequate rheological profile for printability, and hence, 3D printing of cross-linked networks is challenging and normally requires postprinting modifications to obtain the desired scaffolds. In this work, we took advantage of the crystallization process of poly­(ethylene glycol) to print non-isocyanate poly­(hydroxyurethane) hydrogels with tunable mechanical properties. As a consequence of the crystallization process, the hydrogel modulus can be tuned up to 3 orders of magnitude upon heating up to 40 °C, offering an interesting strategy to directly 3D-print hydrogels without the need of postprinting cross-linking. Moreover, the absence of any toxicity makes these materials ideal candidates for biomedical applications.

Bio-based non-isocyanate poly(hydroxy urethane)s (PHU) derived from vanillin and CO2

“…The same effect is not found in the other PHUs, in which the aromatic ring of the hydroquinone (13,14) and vanillyl alcohol (11, 12) possess a higher degree of rotational freedom. The higher T g of the hydroquinone-based PHUs (13,14) with respect to the vanillin alcohol-based PHUs (11,12) is probably due to the methanolic group attached to the aromatic ring of the vanillin alcohol, which increases the mobility of the polymer chain.…”

“…1,10,11 Although this strategy is highly efficient, it also poses significant health and environmental risks. [11][12][13] The major issue is the use of intrinsically toxic diisocyanate monomers. This is particularly important as the industrial production of isocyanates uses phosgene as a precursor.…”

Dynamic Urea Bond‐Mediated Polymerization for Solvent‐Free Low‐Ð Linear Polyurethanes of Controlled Molar Mass: Hypothesis of Diffusion Control

“…Polyurethanes (PUs) form one of the most widely produced classes of polymers due to their wide variety of compositions, and DOI: 10.1002/macp.202200129 consequently properties and applications. [1][2][3][4][5][6][7][8][9][10][11] The growing appeal of sustainable materials and novel polymeric materials for biomedical applications increased the interest in polyurethane synthesis in the past 10 years, specially PEG-based PUs. [12][13][14][15][16][17][18][19][20][21][22][23] However, the control of the molar mass and molar mass dispersity (Ð ≤ 1.5), as well as of the architecture of PU, is still challenging.…”

High-Performance Nonisocyanate Thermoplastic Polythiourethane with High Hydrogen Bond Content

“…6 For decades, nonisocyanate polyurethane/polythiourethane (NIPU/NIPTU) came into being. 7−13 Normally, NIPUs are synthesized by cyclic carbonates and di-/polyamines, including 5-membered, 14−17 6-membered, 18−20 and 8-membered 21 cyclic carbonates. Especially, 5-membered cyclic carbonate (5-CC) is the most popular because it can be synthesized simply and attractively by fixing CO 2 with epoxy resin, which is the most suitable method for carbon neutrality.…”

“…Normally, NIPUs are synthesized by cyclic carbonates and di-/polyamines, including 5-membered, − 6-membered, − and 8-membered cyclic carbonates. Especially, 5-membered cyclic carbonate (5-CC) is the most popular because it can be synthesized simply and attractively by fixing CO 2 with epoxy resin, which is the most suitable method for carbon neutrality. − ,− In some reports, Caillol, ,,, Endo, − Guillaume, ,− and Torkelson , have fully discussed the synthesis of 5-CCs and their reactions with amines to obtain varieties of NIPUs.…”