Microstructural evaluation of poly(vinyl alcohol)‐based hydrogels obtained by freezing‐thawing technique: Thermal analysis and positron annihilation

Paranhos, Caio Márcio; Soares, Bluma G.; Oliveira, Renata Nunes; Pessan, Luiz Antônio; Freitas, Daniela S. de; Windmöller, Dario; Machado, Juliana Costa

doi:10.1002/app.26119

Cited by 12 publications

(7 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recently, we have reported a microstructural analysis of the PVA/PES cryo-gel, using the technique based on positron annihilation lifetime spectroscopy (PALS). It was observed an increase of the average free volume of the samples with increasing the PES content 17 , confirming the interactions between the blend components and also the role of amorphous fraction of cryo-gels samples on the interactions mechanisms between PVA and PES. Since the crystallinity is responsible for the crosslinking points in this system, a decrease of this parameter also decreases the number of available crosslinking points, leading to an increase on the water uptake capacity of the hydrogels, as discussed.…”

Section: Resultssupporting

confidence: 64%

Poly(vinyl alcohol)/sulfonated polyester hydrogels produced by freezing and thawing technique: preparation and characterization

et al. 2007

View full text Add to dashboard Cite

Poly(vinyl alcohol) (PVA) hydrogels were obtained by freezing (-22 °C) and thawing (+25 °C) process, resulting in a semi-interpenetrating polymer network (s-IPN) with a sulfonated polyester (PES). The cryo-gels samples were analysed in terms of its water uptake capacity (WU) as a function of pH, temperature and ionic strength. WU of all samples were relatively high, and they showed a reasonable sensitivity to both pH and ionic strength. The pH- and ionic strength dependence is attributed to the dissociation of ionizable groups of PES. The degrees of crystallinity of the cryo-gels, determined by using differential scanning calorimetry (DSC), are lower than pure PVA. Besides, decrease of glass transition temperature (Tg) of the samples when compared with pure PVA was observed. This results are due interactions between PVA and PES, which lead to an increase on the amorphous content of the hydrogels. Our results show that, despite of changes in the microstructure of the hydrogels due the presence of the polyelectrolyte, the cryo-gels reveal a long-term stability

show abstract

Section: Resultssupporting

confidence: 64%

Poly(vinyl alcohol)/sulfonated polyester hydrogels produced by freezing and thawing technique: preparation and characterization

et al. 2007

View full text Add to dashboard Cite

show abstract

“…Thermal analysis of the samples was conducted using Differential Scanning Calorimetry (Perkin Elmer, DSC 8000), where samples were cut (approximately 10 mg of each sample) and heated at a rate of 10°C/min from room temperature to 250°C. The second cycle of heating was used to analyze the samples' glass transition temperature ( T g ), melting temperature ( T m ) and degree of crystallinity ( X c ), based on the melting enthalpy of the PVA 100% crystalline , X c(100%) = 138.6 J/g. The degree of crystallinity was calculated according to Eq .…”

Section: Methodsmentioning

confidence: 99%

Absorbent polyvinyl alcohol–sodium carboxymethyl cellulose hydrogels for propolis delivery in wound healing applications

Oliveira

Moreira

Thiré

et al. 2017

Polymer Engineering & Sci

View full text Add to dashboard Cite

Second degree burns require dressings to heal. The ideal dressing should keep a moist environment, have low cost, be elastic and have a bactericidal effect. The potential of PVA-NaCMC (sodium carboxymethyl cellulose) gels to combine the mechanical and swelling properties of PVA with the flexibility and high water uptake of NaCMC and the antimicrobial characteristics of propolis is investigated. The freeze-thawed gels were characterized by FTIR and DSC. Their swelling behavior, their mechanical response, the delivery of active compounds and their antimicrobial properties were also determined. The main findings of the FTIR analysis were that no chemical bonding occurred between the materials. The DSC analysis revealed that the addition of NaCMC to PVA lowered the PVA crystallinity, as did the addition of propolis, leading to a more deformable gel (as can be observed from the tensile tests results). This also resulted in a higher rate of delivery of active compounds, higher weight loss and higher fluid uptake than comparable PVA-propolis systems, as shown by the swelling tests and by the propolis delivery tests. Samples with 15% propolis content or more inhibited S. aureus colonies with 80% reduction, and are therefore highly absorbent and compliant antimicrobial gels for wound healing.

show abstract

“…The analysis was performed using the second cycle of heating in order to prevent the influence of the samples thermal history. To calculate the X c , the enthalpy of the melting peak of PVA of each sample (Δ H ) and the melting enthalpy of the PVA 100% crystalline, X c (100%) = 138.6 J/g were adopted using the equation: X c = 100 Δ H / X c (100%) .…”

Section: Methodsmentioning

confidence: 99%

Comparative analysis of PVA hydrogels incorporating two natural antimicrobials: Punica granatum and Arnica montana tinctures

Oliveira

Paranhos

Moreira

et al. 2017

J of Applied Polymer Sci

View full text Add to dashboard Cite

Poly(vinyl alcohol) (PVA) hydrogels are biocompatible materials that retain relatively high amounts of aqueous fluids in their network. The incorporation of antimicrobial natural products, such as pomegranate and arnica, is a strategy for coupling their bactericidal effects with the favorable properties of the gels for wound healing treatment. The goal of this work was to investigate the microstructural, mechanical, and release properties of PVA-pomegranate and PVA-arnica samples. Physical interactions were observed by Fourier transform infrared spectra in PVA-pomegranate samples. The addition of pomegranate to PVA led to high T g , probably related to the physical interactions, and low T m and X c , possibly due to the pomegranate location between PVA chains. Increased levels of arnica were associated with a slight decrease in samples' X c , probably due to a physical barrier imposed by arnica to the interaction of PVA chains. PVA samples presented higher swelling than the samples containing natural products. High amounts of pomegranate in the samples led to high weight loss and high phenols and flavonoids delivery. Arnica release seemed to be more difficult than the pomegranate release. All samples presented relative high mechanical properties. In addition, pomegranate samples present higher potential to deliver active compounds than arnica samples.

show abstract

Microstructural evaluation of poly(vinyl alcohol)‐based hydrogels obtained by freezing‐thawing technique: Thermal analysis and positron annihilation

Cited by 12 publications

References 22 publications

Poly(vinyl alcohol)/sulfonated polyester hydrogels produced by freezing and thawing technique: preparation and characterization

Poly(vinyl alcohol)/sulfonated polyester hydrogels produced by freezing and thawing technique: preparation and characterization

Absorbent polyvinyl alcohol–sodium carboxymethyl cellulose hydrogels for propolis delivery in wound healing applications

Comparative analysis of PVA hydrogels incorporating two natural antimicrobials: Punica granatum and Arnica montana tinctures

Contact Info

Product

Resources

About