Crystallization in films of polar vinyl polymers—I. Crystallinity of polyvinyl alcohol films prepared by evaporation of aqueous solutions

Packter, A.; Nerurkar, M. S.

doi:10.1016/0014-3057(68)90050-5

Cited by 17 publications

(9 citation statements)

References 21 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: 92%

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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: 92%

“…In particular, we concentrate on poly(vinyl alcohol) (PVA), which undergoes a sol-gel transition in water at 20°C for concentrations between 20 and 40 wt% (13,14). This gelation results from the physical cross-linking of PVA chains that associate through hydrogen bonds and form crystallites (14).…”

Section: Significancementioning

confidence: 99%

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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“…Annealing of the polymer membranes above the glass transition temperature (T~ = 85.0 ~ [28]) was performed to introduce the crystalline phase. The dried membranes were annealed at 90 ~ 105 ~ and 120 ~ for 15, 30, 45, 60, 75, or 90 rain.…”

Section: Membrane Preparationmentioning

confidence: 99%

Solute diffusion in swollen membranes VII. Diffusion in semicrystalline networks

Harland

Peppas

1989

Colloid & Polymer Sci

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A model is developed to express the solute diffusion coefficient through semicrystalline polymeric networks. The crystallites create impermeable diffusional barriers around the amorphous regions. Solute diffusion is determined by applying a transport model to the amorphous phase and incorporating the crosslinked polymer structure characteristics. This model is tested with theophylline and vitamin B12 permeation experiments through semicrystalline poly(vinyl alcohol) membranes prepared by annealing of amorphous PVA membranes. The degree of crystallinity varies between 23.1% and 40.5 % on a dry basis. The solute diffusion coefficients correlate well with various parameters of the model.

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“…Previous workers have reported the crystallization of polyvinyl alcohol in the form of single crystals from dilute polyol solutions (1,2). W e have recently been studying the phenomena that occur during film formation from concentrated solutions in these solvents (3,4). W e have observed spherulitic crystallization in many of these films.…”

mentioning

confidence: 99%

“…We first carried out some preliminary studies (4) to obtain the phase (w,) g e 1, the composition for gelation and significant rate of nucleation (3). A s evaporation is continued, spherulite growth and further nucleation then occur simultaneously and rapidly to give films with high degree of spherulitic crystallinity (Fig.…”

mentioning

confidence: 99%