Nucleation roles of cellulose nanocrystals and chitin nanocrystals in poly (ε-caprolactone) nanocomposites

Using polysaccharide nanocrystals such as chitin nanocrystals (ChNCs) or cellulose nanocrystals (CNCs) as fillers of biodegradable aliphatic polyesters is an attractive approach of fabricating completely biodegradable nano composites. Most aliphatic polyesters are semi-crystalline and hence to reveal the effect of nanocrystals on their crystallization behaviors is key to regulate final properties of the nanocomposites. In this work, poly(epsilon-capro-lactone) (PCL) nanocomposites filled with ChNCs and CNCs were prepared as templates for the study. It is intriguing that these two nanocrystals play completely different roles towards crystallization of PCL. CNCs are nucleating agent, promoting nucleation of PCL and accelerating subsequent crystal growth; while ChNCs are anti-nucleation agent, retarding nucleation of PCL and depressing whole process of PCL crystallization. This difference arises from different particle-polymer affinities in the nanocomposites, which is confirmed by the thermodynamic and rheological tests. This work provides valuable information around tuning the thermal properties of polysaccharide nanocrystals filled polymeric nanocomposites.

Automated summary

Using polysaccharide nanocrystals as fillers in biodegradable polyesters can create completely biodegradable nanocomposites. The study found that chitin nanocrystals and cellulose nanocrystals have completely different effects on the crystallization of poly(epsilon-capro-lactone) (PCL). Chitin nanocrystals retard the nucleation and overall crystallization process of PCL, while cellulose nanocrystals promote nucleation and accelerate crystal growth.