Sustained Dye Release Using Poly(urea-urethane)/Cellulose Nanocrystal Composite Microcapsules

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Polymeric microspheres are utilized in various applications, but often lack sufficient mechanical strength and controlled release properties.
• Cellulose nanocrystals (CNCs) offer a sustainable and renewable reinforcement option for polymeric materials.
• Improving the dispersion of CNCs within polymer matrices is crucial for effective reinforcement.

Purpose of the Study:

• To develop eco-friendly microcapsules by reinforcing polymeric microspheres with modified cellulose nanocrystals (mCNCs).
• To investigate the impact of surface-modified CNCs on the properties and performance of polyurea (PU) microcapsules.
• To evaluate the sustained release capabilities and mechanical integrity of the developed composite microcapsules.

Main Methods:

• Surface hydrophobization of CNCs via grafting poly(lactic acid) oligomers and fatty acids.
• Fabrication of polyurea (PU) microcapsules incorporating modified CNCs (mCNCs) using interfacial polymerization.
• Characterization using FT-IR, TGA, OM, SEM, and single-capsule compression tests.
• Encapsulation efficiency and release rate studies using UV-vis spectroscopy with a model hydrophobic dye.

Main Results:

• Modified CNCs (mCNCs) showed enhanced dispersion within the PU shell.
• The mCNC-embedded PU microcapsules exhibited strong, dense walls with improved mechanical strength and rupture resistance.
• Sustained release of a hydrophobic model dye was achieved, indicating effective barrier properties.
• The extended diffusion path length provided by mCNCs contributed to reduced leakage.

Conclusions:

• Reinforcing polyurea microcapsules with surface-modified cellulose nanocrystals creates robust, eco-friendly materials.
• These composite microcapsules demonstrate excellent barrier properties and mechanical strength for sustained release applications.
• The developed method offers a promising approach for creating advanced microcapsules for medicines, nutrients, and other sensitive materials.