Intrinsically stretchable conjugated polymers are seen as promising candidates for next-generation wearable electronics. However, achieving this strain-insensitive performance depends heavily on the careful optimisation of molecular weight. In this comprehensive review, the research team outlines how molecular weight influences the microstructure of polymer films, affecting solution aggregation, chain entanglement and phase separation. Reading tip: Functional CoatingsThe EC Tech Report “Functional Coatings” gives you an up-to-date bundle on functional coatings with articles, videos and other handpicked content. In their outlook, the researchers emphasise that controlling molecular weight is a promising strategy for designing mechanically robust stretchable conjugated polymer films.