Self-Nucleation Phenomena in Polymer Crystallization

Self-nucleation in polymer crystallization refers to the retention or creation of crystalline nuclei within a polymer melt upon partial or complete melting. Unlike heterogeneous nucleation, which relies on foreign surfaces or impurities, self-nucleation exploits residual lamellar fragments or ordered domains that survive above the nominal melting temperature. These surviving entities serve as athermal seeds, reducing the energy barrier for recrystallization and accelerating crystal growth. The process is commonly described in terms of three thermal domains: full melting (no nuclei), self-nucleation (thermal window in which stable self-nuclei exist), and annealing (temperature regime where annealing of residual crystals occurs). Understanding these domains enables precise control of crystallisation kinetics, morphological development and final material properties. Self-nucleation underpins melt-memory effects, whereby a polymer “remembers” its prior crystalline state, influencing subsequent cooling or isothermal crystallisation. This interplay between thermal history, chain architecture and intermolecular interactions is central to tailoring mechanical strength, barrier performance and processing efficiency across industries ranging from packaging to high-performance composites.

Research from Nature Portfolio

No recent Nature Portfolio content available.

Research from all publishers

Recent work on poly(ε-caprolactone) has elucidated how molecular weight governs both crystallisation and melt-memory effects. A systematic study of samples spanning from 0.5 to 70 kg mol⁻¹ revealed a bell-shaped dependence of primary nucleation rate, spherulitic growth and overall crystallisation kinetics on chain length. Above a critical molecular weight, chain folding and entanglement levels enhance the stability of self-nuclei, thereby intensifying melt memory and accelerating crystal formation.

Investigations into isodimorphic random copolyesters, notably poly[(butylene succinate)-ran-(ε-caprolactone)], have shown that even minor comonomer incorporation (∼1 mol %) disrupts the lattice of the major component, sharply reducing the production and stability of self-nuclei. This finding highlights the sensitivity of melt-memory phenomena to subtle changes in crystalline unit-cell composition and offers a route to modulate crystallisation behaviour through controlled copolymerisation.

Studies on carbon‐fibre‐reinforced polyphenylene sulfide (PPS) during secondary thermoforming have illuminated the role of successive thermal cycles on self-nucleation. It was found that refined lamellar structures created in the first cycle persist as effective self-nuclei in the second cycle, largely independent of cooling rate. The work demonstrates that collaborative tuning of heating rate and melt temperature can govern the width of the self-nucleation domain, enabling precise control over crystallisation temperature, rate and resulting mechanical response in composite matrices.

Self-Nucleation Phenomena in Polymer Crystallization publication trend

The graph below shows the total number of articles in self-nucleation phenomena in polymer crystallization across all publications each year (not limited to Nature Index journals).

Technical terms

Self-nucleation: The process by which residual crystal fragments in a polymer melt act as nuclei for recrystallisation without the need for external substrates.

Melt-memory effect: The phenomenon whereby a polymer melt retains information about its previous crystalline state, influencing subsequent crystallisation kinetics and morphology.

Lamellae: Thin, plate-like crystalline regions within semicrystalline polymers formed by folded polymer chains.

Spherulite: Radially growing spherical aggregates of lamellae that form during polymer crystallisation.

Differential scanning calorimetry (DSC): A thermal analysis technique that measures heat flow associated with polymer melting, crystallisation and self-nucleation events.

Isodimorphic copolymer: A random copolymer system in which each comonomer can crystallise in a shared lattice up to a pseudoeutectic composition, affecting self-nucleation behaviour.

References

1. Effect of Molecular Weight on the Crystallization and Melt Memory of Poly(ε-caprolactone) (PCL). Macromolecules (2023).
2. Disappearance of Melt Memory Effect with Comonomer Incorporation in Isodimorphic Random Copolyesters. Macromolecules (2023).
3. The Influence of Thermal Parameters on the Self-Nucleation Behavior of Polyphenylene Sulfide (PPS) during Secondary Thermoforming. Materials (2024).