Novel Applications of Successive Self-nucleation and Annealing Thermal Fractionation for Polymer Characterization

Successive self-nucleation and annealing (SSA) has evolved into a highly sensitive thermal fractionation protocol capable of resolving subtle lamellar and molecular heterogeneities in semicrystalline polymers. Its relevance has intensified over the past decade as SSA has been applied to sustainable, biobased, biodegradable, and mechanically recycled materials, as well as to systems in which crystallization behavior is tightly linked to circularity, processability, and final performance. In this review, we integrate nearly three decades of SSA developments from a longitudinal perspective, placing particular emphasis on how the role and interpretative power of SSA have progressively expanded in material classes that play a key role in sustainability and recyclability, including aliphatic polyesters and biodegradable copolymers, isodimorphic and mixed-mode random copolymers, nanocomposites with complex interfacial crystallization, and recycled polyolefins and biobased blends. Rather than re-establishing already standard protocols, we briefly revisit the experimental foundations of SSA to provide a self-contained framework that supports the interpretation of these applications, highlighting the influence of key variables such as starting temperatures based on self-nucleation temperature (T _s ), holding times at T _s (t _s ), fractionation windows (ΔT _s ), and scanning rates. We then examine how SSA can elucidate comonomer inclusion/exclusion ratios, topology-driven annealing, interfacial nucleation (supernucleation, prefreezing, and antinucleation), and lamellar reorganization during mechanical recycling. Finally, we highlight SSA as an intermediate crystallization condition that bridges kinetic and thermodynamic regimes, enabling refined lamellar populations and amplifying subtle thermal or polymorphic transitions. By reframing SSA as both an analytical and structure-directing crystallization tool, this review provides an integrated roadmap for researchers aiming to exploit its full potential in the rational design of sustainable, recyclable, and high-performance semicrystalline polymers.