Crystallization of a Self-Assembling Nucleator in Poly(l-lactide) Melt

Area of Science:

• Polymer Science and Engineering
• Materials Science
• Crystallization Kinetics

Background:

• Poly(l-lactic acid) (PLLA) is a biodegradable polymer with limited crystallization rates.
• Nucleating agents are crucial for enhancing polymer crystallization.
• Self-assembling nucleators offer unique structural advantages.

Purpose of the Study:

• To investigate the crystallization behavior of N,N',N″-tricyclohexyl-1,3,5-benzenetricarboxamide (TMC-328) in a PLLA matrix.
• To quantify the relationship between supersaturation, fibril density, and crystallization kinetics.
• To determine key nucleation parameters for TMC-328 in PLLA and understand its effect on PLLA crystallization.

Main Methods:

• Optical microscopy to quantify TMC-328 crystal nuclei density.
• Rheological measurements to assess TMC-328 network formation and crystallization rates.
• Application of classical nucleation theory to determine interfacial energy and critical nucleus properties.

Main Results:

• TMC-328 self-assembles into a fibrous network, with density increasing as temperature decreases.
• Both TMC-328 fibril density and crystallization kinetics show a power law dependence on supersaturation.
• PLLA crystallization rate significantly increases with higher TMC-328 fibril density, forming hybrid shish-kebab structures.

Conclusions:

• TMC-328 acts as an effective nucleator for PLLA, with its self-assembled structure dictating crystallization behavior.
• The study provides the first determination of solid-melt interfacial energy, critical nucleus size, and molecule count for TMC-328 in PLLA.
• Enhanced PLLA crystallization and hybrid shish-kebab morphology are achieved through controlled TMC-328 self-assembly and density.