Investigating structural and dynamic changes in cellulose due to nanocrystallization

Area of Science:

• Materials Science
• Nanotechnology
• Biomaterials

Background:

• Cellulose is a abundant biopolymer with diverse applications.
• Nanocrystalline cellulose (CNCs) offers unique properties due to its nanoscale structure.
• Understanding CNCs' structural and dynamic behavior is key for advanced material design.

Purpose of the Study:

• To synthesize and characterize cellulose nanocrystals (CNCs) from alpha-cellulose.
• To investigate the structural, optical, and dynamic properties of CNCs.
• To establish a correlation between crystallinity and nuclear spin dynamics in CNCs.

Main Methods:

• Acid hydrolysis for CNC synthesis.
• Microscopic (SEM, TEM) and spectroscopic (PXRD, XPS, Raman, FTIR, PL, UV-Vis) analyses.
• Solid-state Nuclear Magnetic Resonance (¹³C CP-MAS SSNMR) and NMR relaxometry.

Main Results:

• CNCs demonstrated significantly higher photoluminescence intensity and crystallinity index than cellulose.
• ¹³C CP-MAS SSNMR confirmed a substantial reduction in amorphous content in CNCs.
• NMR relaxometry indicated longer spin-lattice relaxation times and local correlation times in CNCs, correlated with enhanced crystallinity.

Conclusions:

• The study successfully synthesized and characterized CNCs, highlighting their improved optical and structural properties.
• A direct correlation between the crystallinity index and nuclear spin dynamics was established using NMR relaxometry.
• Findings provide crucial insights into CNCs' structure and dynamics for biomimetic material design in pharmaceuticals, textiles, and cosmetics.