Evaporation-Induced Self-Assembly: Multiple Solvent-Dependent Pathways in High-χ Block Copolymers

Abstract Evaporation-induced self-assembly (EISA) provides versatile nonequilibrium pathways for directing nanoscale ordering in high-χ block copolymer systems; however, solvent-dependent kinetic pathway selection remains insufficiently understood. Herein, high-χ PMMA-b-PDMS-b-PMMA triblock copolymers synthesized via environmentally conscious ARGET/ICAR ATRP approaches were employed as model systems to investigate solvent-mediated EISA behavior. By systematically varying polymer composition and solvent environment, an EISA/SAXS morphology library comprising 40 polymer–solvent combinations was established using solvents spanning broad solubility parameters and vapor pressures. Transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) analyses revealed substantial differences between EISA and conventional thermal annealing (TA) pathways. Depending on polymer composition and solvent environment, EISA generated diverse nanostructures including packed spheres, cylinders, lamellae, and perforated lamellae with characteristic d-spacings of approximately 14–35 nm. Quantitative ordering analyses further demonstrated that solvent selectivity and evaporation kinetics strongly influence higher-order structural development, kinetic trapping, and long-range ordering evolution. Notably, several EISA-processed samples exhibited ordering characteristics approaching those of thermally annealed systems, whereas other solvent environments stabilized metastable or mixed nanostructures not readily accessible through conventional annealing alone. Machine-learning-assisted analyses further identified predictive associations between key polymer/solvent descriptors and nanoscale structural evolution, enabling data-driven processing–structure mapping of solvent-mediated EISA pathways. Overall, this work establishes an experimentally grounded, data-driven framework for understanding kinetic pathway selection in high-χ block copolymer self-assembly and highlights EISA as a versatile processing strategy beyond conventional thermal annealing.