A pH-Sensitive Lignin-Based Material for Sustained Release of 8-Hydroxyquinoline.

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomass Valorization

Background:

• Lignin-based materials are explored for pH-sensitive applications.
• Existing pH-sensitive mechanisms in lignin are limited by hydroxyl/carboxyl content.
• Novel mechanisms are needed for advanced lignin-based smart materials.

Purpose of the Study:

• To construct a novel pH-sensitive lignin-based polymer with a unique mechanism.
• To characterize the polymer's structure and 8-hydroxyquinoline (8HQ) substitution.
• To evaluate the sustained release and pH-sensitive properties of the new material.

Main Methods:

• Ester bond formation between lignin and 8-hydroxyquinoline (8HQ).
• Comprehensive structural characterization of the synthesized polymer.
• Dialysis method to assess 8HQ sustained release and pH sensitivity.

Main Results:

• Achieved up to 46.6% substitution degree of 8HQ.
• Demonstrated 60 times slower sustained release of 8HQ compared to physical mixtures.
• Exhibited excellent pH sensitivity, with higher 8HQ release in alkaline conditions (pH=8) than acidic (pH=3, 5).

Conclusions:

• A new pH-sensitive lignin-based polymer with a novel mechanism was successfully fabricated.
• The polymer shows significant potential for high-value lignin utilization.
• This work provides theoretical guidance for developing new pH-sensitive lignin-based polymers.