The role of crystallization and phase separation in the formation of physically cross-linked PVA hydrogels

Holloway, Julianne L.; Lowman, Anthony M.; Palmese, Giuseppe R.

doi:10.1039/c2sm26763b

Cited by 266 publications

(243 citation statements)

References 40 publications

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“…4 C and D). This is consistent with the value of 30 ± 10 wt% reported for the gelation concentration of PVA in water at 20°C (13,28). These results demonstrate that film growth can be tailored by adjusting the properties of the solution (Φ 0 , Φ c ) and substrate (R 0 ) as well as the swelling parameters (R ∞ , D 0 ), all of which are well characterized by standard techniques.…”

Section: Characterization Of Hydrogel Film Growth As a Function Of Susupporting

confidence: 81%

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: Characterization Of Hydrogel Film Growth As a Function Of Susupporting

confidence: 81%

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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“…Crystallization and phase separation are two important mechanisms that contribute to the structure of PVA-C, with crystallization occurring in the first three FTCs and phase separation through at least six cycles. Phase separation has a very important impact on the mechanical properties of PVA, even apart from crystallization [14].…”

Section: Processing Parameters For Pva-c Preparationmentioning

confidence: 99%

Poly(Vinyl Alcohol) Cryogels for Biomedical Applications

Wan

Bannerman

Yang

et al. 2014

Advances in Polymer Science

116

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“…As demonstrated by researchers, phase separation into a PVA-rich phase and a water-rich phase is the crucial and unique mechanism that occurs in the process of freezethawed PVA hydrogel gelation [46]. During freezing process, water froze, while the polymers were expelled to form regions of concentrated polymer.…”

Section: Microstructurementioning

confidence: 99%

Effects of polymerization degree on recovery behavior of PVA/PVP hydrogels as potential articular cartilage prosthesis after fatigue test

Yan¹,

Xiong²,

Peng³

et al. 2016

Express Polym. Lett.

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Abstract. Poly (vinyl alcohol)/poly (vinyl pyrrolidone) (PVA/PVP) hydrogels with various polymerization degrees of PVA were synthesized by a repeated freezing-thawing method. The influence of polymerization degree on microstructure, water content, friction coefficient, compressive fatigue and recovery properties of PVA/PVP hydrogels were investigated. The results showed that higher polymerization degree resulted in larger compressive modulus and lower friction coefficient. The fatigue behaviors of PVA/PVP hydrogels were evaluated under sinusoidal compressive loading from 200 to 800 N at 5 Hz for up to 50 000 cycles. The unconfined uniaxial compressive tests of PVA/PVP hydrogels were performed before and after fatigue test. During the fatigue test, the height of the hydrogel rapidly decreased at first and gradually became stable with loading cycles. The compressive tangent modulus measured 0 h after fatigue was significantly larger than the values obtained before test, and then the modulus recovered to its original level for 48 h after test. However, the geometry of hydrogels could not return to the original level due to the creep effects. PVA/PVP hydrogels prepared with lower polymerization degree showed better recovery capability than that prepared with high polymerization degree.

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The role of crystallization and phase separation in the formation of physically cross-linked PVA hydrogels

Cited by 266 publications

References 40 publications

Hydrogel films and coatings by swelling-induced gelation

Hydrogel films and coatings by swelling-induced gelation

Poly(Vinyl Alcohol) Cryogels for Biomedical Applications

Effects of polymerization degree on recovery behavior of PVA/PVP hydrogels as potential articular cartilage prosthesis after fatigue test

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