Covalently crosslinked ultrathin films can be fabricated layer-by-layer by exploiting fast and efficient click-type reactions between polyamines and the 'spring-loaded' functionality of poly(2-alkenyl azlactone)s. The accessibility and reactivity of residual azlactone functionality in these ultrathin materials permits further functionalization post-fabrication, suggesting new approaches to the modification, passivation, or patterning of curved or topologically complex surfaces with chemical or biological functionality.