Phase separation in block copolymer systems: From thermodynamics to industrial applications

Block copolymers exhibit unique phase separation and structural transitions, making them highly relevant in industrial applications. This review provides a critical analysis of block copolymer systems, focusing on the thermodynamics of micro- and macro-phase separation and their ability to self-assemble into diverse morphologies. Grounded in the Flory-Huggins model, key factors such as segregation strength, solvent selectivity, molecular architecture (e.g. polydispersity and grafting sites), shear forces, and temperature are examined for their impact on phase behaviour in neat systems and in solution. Viscoelastic properties, particularly the storage (G') and loss (G") moduli, are analysed as dynamic indicators of phase transitions, enabling the identification of temperature ranges for phase separation and system dynamics across various morphologies. The influence of external stimuli such as shear and thermal fields is also discussed, with attention to their role in directing morphology across micellar, cubic, hexagonal, and lamellar phases. This review provides an overview of the current knowledge in the field, summarizing key advances and emerging applications. Special attention is given to potential developments in areas such as nanolithography, drug delivery, membrane technology, energy storage, photonics and catalysis. In doing so, the paper highlights emerging research directions and the role of thermodynamic and structural control in designing functional materials. By offering new perspectives on phase behaviour and self-assembly mechanisms, this work aims to guide the development of next-generation polymeric systems for emerging technologies.