Radically new cellulose nanocomposite hydrogels: Temperature and pH responsive characters.

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Stimuli-responsive hydrogels offer tunable properties for advanced applications.
• Developing novel hydrogel compositions with tailored responses remains a key research area.
• Cellulose nanowhiskers (CNW) present a sustainable building block for advanced materials.

Purpose of the Study:

• To synthesize and characterize novel stimuli-responsive hydrogels.
• To investigate the incorporation of cellulose nanowhiskers-polyacrylamide (CNW-PAAm) copolymer into a poly N-isopropyl acrylamide (PNIPAm) semi-interpenetrating network (IPN).
• To evaluate the pH and temperature-responsive behavior of the resulting nanocomposite hydrogels.

Main Methods:

• Free radical polymerization was used to prepare the CNW-PAAm copolymer.
• The copolymer was incorporated into a PNIPAm semi-IPN hydrogel system via free radical polymerization.
• Characterization included Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and swelling ratio measurements.

Main Results:

• The synthesized nanocomposite hydrogels demonstrated both pH and temperature responsiveness.
• Highest equilibrium swelling ratio (ESR) was observed at acidic pH (pH 4).
• Good swelling behavior and hydrophilicity were noted at 32°C.
• SEM analysis revealed a homogenous network structure with interconnected pores (30-100 nm).

Conclusions:

• The novel CNW-PAAm-PNIPAm nanocomposite hydrogels exhibit dual stimuli-responsive characteristics.
• The incorporation of CNW-PAAm copolymer successfully imparts desired pH and temperature sensitivity to the PNIPAm network.
• These findings suggest potential applications for these hydrogels in areas requiring controlled swelling and release.