Functionalized Boron Nitride Nanosheets/Poly(l-lactide) Nanocomposites and Their Crystallization Behavior

Area of Science:

• Materials Science
• Polymer Science
• Nanotechnology

Background:

• Poly(l-lactide) (PLLA) is a biodegradable polymer with potential applications in various fields.
• Improving the crystallization behavior and properties of PLLA is crucial for its wider adoption.
• Boron nitride nanosheets (BNNS) are promising nanofillers due to their unique thermal and mechanical properties.

Purpose of the Study:

• To prepare hydroxyl-functionalized boron nitride nanosheets (OH-BNNS).
• To investigate the effects of OH-BNNS on the crystallization, melting, and crystal structure of PLLA.
• To understand the dispersion mechanisms and interactions between PLLA and OH-BNNS.

Main Methods:

• Preparation and characterization of OH-BNNS.
• Blending OH-BNNS with PLLA to form nanocomposites.
• Differential scanning calorimetry (DSC) for thermal analysis.
• X-ray diffraction (XRD) for crystal structure analysis.
• Microscopy techniques for morphology observation.

Main Results:

• OH-BNNS were successfully prepared and dispersed in PLLA via hydrogen bonding.
• OH-BNNS accelerated PLLA crystallization and increased nucleation density, resulting in smaller spherulites.
• Crystallinity increased with OH-BNNS addition, showing a more pronounced crystallization peak upon cooling.
• Cold crystallization upon heating was weakened, and crystal structure (α- vs. α'-crystal) was dependent on OH-BNNS loading.

Conclusions:

• OH-BNNS act as effective nucleating agents for PLLA.
• The interaction between PLLA and OH-BNNS influences the crystallization kinetics and crystal polymorphism.
• PLLA/OH-BNNS nanocomposites exhibit enhanced crystallization properties, with potential for tailored material characteristics.