Effect of Increasing Polyvinyl Alcohol Content on the Porous Structure and Mechanical Properties of Sol-Gel Derived Hybrids Foams

2007 ◽  
Vol 361-363 ◽  
pp. 555-558 ◽  
Author(s):  
Agda Aline Rocha de Oliveira ◽  
R.L. Oréfice ◽  
Herman S. Mansur ◽  
Marivalda Pereira
Keyword(s):  
Mechanical Properties ◽  
Polyvinyl Alcohol ◽  
Bioactive Glass ◽  
Structural Characteristics ◽  
Sol Gel ◽  
Acetate Solution ◽  
Compression Tests ◽  
Sol Gel Process ◽  
Hybrid Foams

Bioactive glass/polymer hybrids are promising materials for biomedical applications because they combine the bioactivity of these bioceramics with the flexibility of polymers. In previous work hybrid foams with 80% bioactive glass and 20% polyvinyl alcohol (PVA) were prepared by the sol-gel process for application as scaffold for bone tissue engineering. In this work it was evaluated the effect of increasing the PVA content of the hybrids on structural characteristics and mechanical properties of hybrid foams produced by this method. The hybrids were prepared with inorganic phase composition of 70%SiO2-30%CaO and PVA fractions of 20 to 60% by the sol-gel method. The structural and mechanical characterization of the obtained foams was done by FTIR, SEM, Helium Picnometry, and compression tests. To reduce the acidic character of the hybrids due to the catalysts added, different neutralization solutions were tested. The immersion of hybrids in a calcium acetate solution was the most adequate neutralization method, avoiding calcium loss while maintaining pH nearly 7,0 and low PVA loss. The foams presented porosity of 60-85% and pore diameters of 100-500μm with interconnected structure. The pore structure varied with the polymer content in the hybrid. The compression tests showed that an increase of PVA fraction in the hybrids improved their mechanical properties.

Mechanical Behavior of Bioactive Glass-Polyvinyl Alcohol Hybrid Foams Obtained by the Sol-Gel Process

2005 ◽  
Vol 284-286 ◽  
pp. 757-760 ◽  
Author(s):  
Marivalda Pereira ◽  
Showan N. Nazhat ◽  
Julian R. Jones ◽  
Larry L. Hench
Keyword(s):  
Polyvinyl Alcohol ◽  
Bioactive Glass ◽  
Mechanical Behavior ◽  
Sol Gel ◽  
Precursor Solution ◽  
High Porosity ◽  
Soft Tissue Regeneration ◽  
Sol Gel Process ◽  
Potential Applications ◽  
Hybrid Foams

The possibility of enhancing mechanical properties by incorporation of polymeric components to sol-gel derived materials is extremely attractive to prepare macroporous scaffolds, leading to materials with potential applications in both hard and soft tissue regeneration. In this work bioactive glass-polyvinyl alcohol hybrids were developed and their mechanical behavior was evaluated. Hybrids were synthesized by adding polyvinyl alcohol to a sol-gel precursor solution, which was then foamed with the addition of a surfactant and vigorous agitation. The foams were cast, aged and dried at 40°C. A cleaning step to decrease the acidic character of the obtained hybrids was undertaken by immersion in a NH4OH solution. The mechanical behavior of the hybrids was evaluated in compression using both stress and strain control tests. Hybrid foams had a high porosity varying from 60-90% and the macropore diameter ranged from 10 to 600 µm. The modal macropore diameter varied with the inorganic phase composition and with the polymer content in the hybrid. The strain at fracture of the as prepared hybrid foams was substantially greater than pure gel-glass foams. The cleaned hybrids presented a slightly higher strength and lower deformation than the as prepared foams.

Hybrid Bioactive Glass-Polyvinyl Alcohol Prepared by Sol-Gel

2008 ◽  
Vol 587-588 ◽  
pp. 62-66 ◽  
Author(s):  
Hermes S. Costa ◽  
Alexandra A.P. Mansur ◽  
Edel Figueiredo Barbosa-Stancioli ◽  
Marivalda Pereira ◽  
Herman S. Mansur
Keyword(s):  
Mechanical Properties ◽  
Polyvinyl Alcohol ◽  
Bioactive Glass ◽  
Sol Gel ◽  
Degree Of Hydrolysis ◽  
Bioactive Glasses ◽  
Composite Foams ◽  
Composition Ratios ◽  
Hybrid Scaffolds ◽  
Hydrolysis Of

Bioactive glasses are materials that have been used for the repair and reconstruction of diseased bone tissues, as they exhibit direct bonding with human bone tissues. However, bioactive glasses have low mechanical properties compared to cortical and cancellous bone. On the other hand, composite materials of biodegradable polymers with inorganic bioactive glasses are of particular interest to engineered scaffolds because they often show an excellent balance between strength and toughness and usually improved characteristics compared to their individual components. Composite bioactive glass-polyvinyl alcohol foams for use as scaffolds in tissue engineering were previously developed using the sol-gel route. The goal of this work was the synthesis of composite foams modified with higher amounts of PVA. Samples were characterized by morphological and chemical analysis. The mechanical behavior of the obtained materials was also investigated. The degree of hydrolysis of PVA, concentration of PVA solution and different PVA-bioactive glass composition ratios affect the synthesis procedure. Foams with up to 80 wt% polymer content were obtained. The hybrid scaffolds obtained exhibited macroporous structure with pore size varying from 50 to 600 µm and improved mechanical properties.

Acid character control of bioactive glass/polyvinyl alcohol hybrid foams produced by sol–gel

2008 ◽  
Vol 47 (3) ◽  
pp. 335-346 ◽  
Author(s):  
A. A. R. de Oliveira ◽  
V. Ciminelli ◽  
M. S. S. Dantas ◽  
H. S. Mansur ◽  
M. M. Pereira
Keyword(s):  
Polyvinyl Alcohol ◽  
Bioactive Glass ◽  
Sol Gel ◽  
Hybrid Foams ◽  
Acid Character

Preparation of bioactive glass-polyvinyl alcohol hybrid foams by the sol-gel method

2005 ◽  
Vol 16 (11) ◽  
pp. 1045-1050 ◽  
Author(s):  
M. M. Pereira ◽  
J. R. Jones ◽  
R. L. Orefice ◽  
L. L. Hench
Keyword(s):  
Polyvinyl Alcohol ◽  
Bioactive Glass ◽  
Sol Gel ◽  
Gel Method ◽  
Sol Gel Method ◽  
Hybrid Foams

Physicochemical Characterization of Novel Chitosan-Soy Protein/ TEOS Porous Hybrids for Tissue Engineering Applications

2006 ◽  
Vol 514-516 ◽  
pp. 1000-1004 ◽  
Author(s):  
S.S. Silva ◽  
J. Miguel Oliveira ◽  
João F. Mano ◽  
Rui L. Reis
Keyword(s):  
Soy Protein ◽  
Sol Gel ◽  
Physicochemical Characterization ◽  
Compression Tests ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Sol Gel Process ◽  
New Type ◽  
Reflectance Ftir

In this paper we report a new type of cross-linked porous structure based on a chitosansoy protein blend system developed by means of combining a sol-gel process with the freeze-drying technique. The final structure was investigated by Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR), contact angle measurements and the morphology by scanning electron microscopy (SEM). The water uptake capability and the weight loss were measured up to 14 days and their mechanical properties were assessed with compression tests. Results showed that the addition of tetraethyl orthosilicate (TEOS) to the chitosan-soy protein blend system provide specific interactions at the interface between the two polymers allowing to tailor the size and distribution as well as the degradation rate of the hybrids. Finally, TEOS incorporation induces an increase of the surface energy that influences the final physicochemical properties of the materials.

scholarly journals Effect of polyvinyl alcohol content and after synthesis neutralization on structure, mechanical properties and cytotoxicity of sol-gel derived hybrid foams

2009 ◽  
Vol 12 (2) ◽  
pp. 239-244 ◽  
Author(s):  
Agda Aline Rocha de Oliveira ◽  
Viviane Silva Gomide ◽  
Maria de Fátima Leite ◽  
Herman Sander Mansur ◽  
Marivalda de Magalhães Pereira
Keyword(s):  
Mechanical Properties ◽  
Polyvinyl Alcohol ◽  
Sol Gel ◽  
Alcohol Content ◽  
Hybrid Foams

Cytotoxicity Evaluation of Bioactive Glass-Polyvinyl Alcohol Hybrid Foams Prepared by the Sol-Gel Method

2005 ◽  
Vol 284-286 ◽  
pp. 589-592 ◽  
Author(s):  
Marivalda Pereira ◽  
Najat Al-Saffar ◽  
Jamuna Selvakumaran ◽  
Larry L. Hench
Keyword(s):  
Tissue Engineering ◽  
Polyvinyl Alcohol ◽  
Cell Viability ◽  
Bioactive Glass ◽  
Pore Structure ◽  
Sol Gel ◽  
Cleaning Procedure ◽  
Gel Method ◽  
Cleaning Methods ◽  
Hybrid Foams

Hybrid bioactive glass-polyvinyl alcohol foams for use as scaffolds in tissue engineering were developed through the sol-gel route. Hybrids produced by this route present a high acidic character due to the catalysts added during processing and may also contain residual organics after the drying step. Therefore, an additional cleaning step is necessary to produce biocompatible materials. In this study hybrid PVA/bioactive glass foams were cleaned using various procedures and cytotoxicity evaluation was conducted. All the cleaning methods used increased the cell viability levels compared to samples not subjected to a cleaning procedure. The most effective cleaning procedure used was the immersion in NH4OH solution. The cleaning procedure changed the composition and pore structure of the final material.

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