Light and pH dual-responsive spiropyran-based cellulose nanocrystals

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Chemistry

Background:

• Cellulose nanocrystals (CNCs) are sustainable nanomaterials with tunable properties.
• Spiropyran (SP) is a photochromic molecule that changes structure and color upon light exposure.
• Developing responsive nanomaterials is crucial for advanced technological applications.

Purpose of the Study:

• To synthesize and characterize novel dual-responsive spiropyran-based cellulose nanocrystals (SP-CNCs).
• To investigate the photochromic and pH-responsive behaviors of SP-CNCs.
• To explore the potential applications of SP-CNCs in areas like sensing and data storage.

Main Methods:

• Carboxyl-containing spiropyran (SP-COOH) was attached to cellulose nanocrystals (CNCs).
• Characterization techniques included FT-IR, elemental analysis, TEM, AFM, DSL, ζ-potential, and UV-Vis spectroscopy.
• Photochromic and pH-responsive properties were systematically evaluated.

Main Results:

• Successful synthesis of SP-CNCs confirmed by spectroscopic and microscopic analyses.
• SP-CNCs exhibited excellent photochromic properties, switching between merocyanine (MC) and spiropyran (SP) forms under UV/Vis light.
• The nanomaterials demonstrated distinct color changes in response to varying pH levels in aqueous solutions.
• SP-CNCs showed enhanced photoresponsiveness, photoreversibility, and stability in DMSO compared to water.

Conclusions:

• SP-CNCs are effectively synthesized and possess dual light and pH responsiveness.
• The observed photochromic and pH-sensing capabilities highlight their potential for visual pH sensing.
• These findings suggest promising applications for SP-CNCs in reversible data storage, optical switching, and light-controlled nanomaterials.