Toughening Immiscible Polymer Blends: The Role of Interface-Crystallization-Induced Compatibilization Explored...

Area of Science:

• Polymer Science and Engineering
• Materials Science
• Crystallization Phenomena

Background:

• Thermodynamically immiscible polymers often exhibit poor interfacial adhesion, limiting their mechanical properties.
• Developing effective compatibilization strategies is crucial for creating high-performance polymer blends.
• Stereocomplexation offers a unique pathway for enhancing polymer interactions.

Purpose of the Study:

• To explore interface-crystallization-induced compatibilization (ICIC) using stereocomplexation for immiscible polymer blends.
• To synthesize and characterize novel reactive interfacial compatibilizers.
• To evaluate the impact of ICIC on the interfacial strength, morphology, and mechanical properties of PVDF/PLLA blends.

Main Methods:

• Synthesis of reactive compatibilizers: poly(styrene-co-glycidyl methacrylate)-graft-poly(l-lactic acid) (SAL) and poly(styrene-co-glycidyl methacrylate)-graft-poly(d-lactic acid) (SAD) via reactive melt blending.
• Preparation of immiscible polyvinylidene fluoride/poly l-lactic acid (PVDF/PLLA) blends.
• Characterization using IR nanoimaging, small amplitude oscillatory shear (SAOS), dynamic mechanical thermal analysis (DMTA), atomic force microscopy (AFM), IR nanospectroscopy, scanning electron microscopy (SEM), and single edge-notch bending (SENB) tests.

Main Results:

• ICIC via stereocomplexation successfully enhanced the interfacial strength of PVDF/PLLA blends.
• Formation of a 200-300 nm thick rigid stereocomplex (SC) crystalline interfacial layer was observed.
• Significant improvements in mechanical properties, including a >20-fold increase in elongation at break and doubled fracture toughness, were achieved.

Conclusions:

• ICIC is a promising strategy for improving interfacial strength and mechanical performance of immiscible polymer blends.
• The formation of a rigid SC crystalline layer at the interface is key to the enhanced properties.
• This approach offers a route to creating tougher and more robust polymer materials.