Microstructure of poly(vinyl alcohol) hydrogels produced by freeze/thaw cycling

Willcox, P. Jeanene; Howie, Douglas W.; Schmidt‐Rohr, Klaus; Hoagland, David A.; Gido, Samuel P.; Pudjijanto, Stephanus; Kleiner, Lothar W.; Venkatraman, Subbu S.

doi:10.1002/(sici)1099-0488(19991215)37:24<3438::aid-polb6>3.3.co;2-0

Cited by 75 publications

(161 citation statements)

References 20 publications

(32 reference statements)

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“…2D). This confirms that physical PVA hydrogels were formed, for which cross-linking crystallites melt in water above 85°C (22,23). Accordingly, the formation of PVA crystallites in these films was verified by X-ray scattering, which revealed the main Bragg peak of PVA crystals (Fig.…”

Section: Resultssupporting

confidence: 75%

Hydrogel films and coatings by swelling-induced gelation

Moreau

Chauvet

François

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Hydrogel films used as membranes or coatings are essential components of devices interfaced with biological systems. Their design is greatly challenged by the need to find mild synthesis and processing conditions that preserve their biocompatibility and the integrity of encapsulated compounds. Here, we report an approach to produce hydrogel films spontaneously in aqueous polymer solutions. This method uses the solvent depletion created at the surface of swelling polymer substrates to induce the gelation of a thin layer of polymer solution. Using a biocompatible polymer that self-assembles at high concentration [poly(vinyl alcohol)], hydrogel films were produced within minutes to hours with thicknesses ranging from tens to hundreds of micrometers. A simple model and numerical simulations of mass transport during swelling capture the experiments and predict how film growth depends on the solution composition, substrate geometry, and swelling properties. The versatility of the approach was verified with a variety of swelling substrates and hydrogel-forming solutions. We also demonstrate the potential of this technique by incorporating other solutes such as inorganic particles to fabricate ceramic-hydrogel coatings for bone anchoring and cells to fabricate cell-laden membranes for cell culture or tissue engineering. H ydrogel films are used in a number of biomedical applications like wound healing (1), drug delivery (1), antiadhesive membranes (2), soft-tissue reconstruction (3, 4), and cell culture (5). The quality of their interactions with biological tissues or entrapped cells is central to the performance of these systems. Although considerable advances have been made in synthesis (6) and processing (7) to tailor these interactions, the toxicity of by-products and the degradation caused by harsh processing conditions remain key issues (8), which can be overcome (9) but are often addressed at the cost of difficult synthesis or multistep processes. There is a great interest for simple, versatile, and in vivo-friendly methods to fabricate and modify hydrogels. We propose a strategy to design hydrogel films in mild conditions. This method could be used to produce freestanding hydrogel membranes or hydrogel coatings to functionalize other hydrogels.Our approach relies on the understanding of transport phenomena occurring near the surface of a polymer network swelling in a polymer solution. As an illustration, let us consider a flat polymer network with thickness H 0 immersed in a solution containing a volume fraction Φ 0 of free polymer chains, as depicted in Fig. 1A. When the solvent of the solution is also a solvent for the network, the network swells in a diffusive process. For early immersion times t, the increase in thickness ΔH is given by the following (10, 11):where H ∞ is the thickness at equilibrium swelling in the polymer solution and D 0 is a diffusivity coefficient depending on the dynamics of the network and of the solution. The systems of interest are those where the chains in solution do not penetrate...

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Section: Resultssupporting

confidence: 75%

Hydrogel films and coatings by swelling-induced gelation

Moreau

Chauvet

François

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…IPHs constitute an important class of materials. They are attracting broad interest both from fundamental and applications viewpoints [28,29].…”

Section: Introductionmentioning

confidence: 99%

New hydrogels based on the interpenetration of physical gels of agarose and chemical gels of polyacrylamide

Fernández¹,

Mijangos²,

Guenet³

et al. 2009

European Polymer Journal

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“…The hydrogels, one of the most promising classes of the biomaterials, have been of great interest to biomaterial scientists for many years, [3][4][5][6][7][8][9][10] and are widely used in drug delivery, tissue engineering, and medical devices.…”

Section: Introductionmentioning

confidence: 99%

Structure formation in injectable poly(lactide‐co‐glycolide) depots. II. Nature of the gel

et al. 2004

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The benzyl benzoate solutions of poly(D,L-lactide-co-glycolide), a random oriented synthesized copolymer with L/G ratio of 50:50, have been shown to form gels during aging and upon injection into buffer or water. The gelation properties influence drug release kinetics for these injectable, depot-forming solutions. In this article, we report on the mechanism of gelation. We find that only polymers that have a certain average block length of glycolide units form gels during aging as well as depots upon in vitro. Thus, gel formation is likely due to the formation of ordered solvated aggregates of blocky glycolide units. Rheometry, differential scanning calorimetry, and nuclear magnetic resonance were used to investigate the gelation kinetics and the polymer molecular parameters. Of all the polymers used, poly(lactide-coglycolide)s with glycolide average block length <2.9 did not show any gelation behavior. The details of the gelation process are also solvent dependent.

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Microstructure of poly(vinyl alcohol) hydrogels produced by freeze/thaw cycling

Cited by 75 publications

References 20 publications

Hydrogel films and coatings by swelling-induced gelation

Hydrogel films and coatings by swelling-induced gelation

New hydrogels based on the interpenetration of physical gels of agarose and chemical gels of polyacrylamide

Structure formation in injectable poly(lactide‐co‐glycolide) depots. II. Nature of the gel

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