PVA Nanofibers as an Insoluble pH Sensor
David Mínguez-García1, Ignacio Montava1, Marilés Bonet-Aracil1
1Departamento de Ingeniería Textil y Papelera, Universitat Politècnica de València, Plaza Ferrándiz y Carbonell nº1, 03801 Alcoy, Spain.
Polymers
|January 17, 2024
Summary
This study cross-linked polyvinyl alcohol (PVA) nanofibers with citric acid (CA) to enhance their stability and retain turmeric's pH-indicating properties. The cross-linked nanofibers maintained their halochromic behavior, showing potential for pH sensing applications.
Area of Science:
- Materials Science
- Polymer Chemistry
- Analytical Chemistry
Background:
- Turmeric, containing curcumin, exhibits halochromic properties useful for pH indication.
- Polyvinyl alcohol (PVA) nanofibers are explored for drug delivery but require insolubilization.
- Previous studies utilized other polymers like chitosan/polyethylene oxide (PEO).
Purpose of the Study:
- To cross-link PVA nanofibers with citric acid (CA) for insolubilization.
- To evaluate the impact of cross-linking on turmeric's halochromic properties.
- To assess the stability and pH-indicating capabilities of modified PVA nanofibers.
Main Methods:
- Polyvinyl alcohol (PVA) nanofibers were synthesized and cross-linked with citric acid (CA).
- Cross-linked and non-cross-linked (NCL) nanofibers were treated with sodium hydroxide (NaOH) solution.
- Halochromic properties were assessed visually and spectroscopically.
- Nanofiber characterization included FTIR spectroscopy and scanning electron microscopy (SEM).
Main Results:
- Thermal treatment induced cross-linking, maintaining nanofiber shape in NaOH solution.
- Non-cross-linked (NCL) samples showed solubilization.
- Cross-linked (CL) PVA nanofibers retained their halochromic behavior despite color variations.
- Esterification occurred between citric acid and curcumin during cross-linking, with CA acting as an acid catalyst.
Conclusions:
- Citric acid effectively cross-links PVA nanofibers, rendering them insoluble.
- The cross-linking process preserves the pH-indicating halochromic properties of turmeric.
- Cross-linked PVA nanofibers loaded with turmeric show promise as stable pH sensors.
