Architecture-Dependent Disintegration Temperature of Electrospun PNIPAM-Based Scaffolds

Abstract

Thermoresponsive electrospun scaffolds based on poly(N-isopropylacrylamide) (PNIPAM) copolymers exhibit morphology-dependent structural disintegration upon cooling to the temperature of the coil-to-globule transition. This behavior does not coincide directly with the classical lower critical solution temperature (LCST) or volume phase transition temperature (VPTT) due to the specific fiber architecture formed by electrospinning. In this study, the Scaffold Disintegration Temperature (SDT) is introduced as an operational descriptor corresponding to the onset of reproducible morphological collapse in fibrous PNIPAM networks. SDT is used as a comparative metric to assess how the macromolecular architecture and processing conditions relate to the scaffold-level stability. Using viscosity-matched statistical and graft copolymers with distinct topologies, architecture-dependent differences in the disintegration behavior were identified. These differences correlate with variations in network morphology and orientational coherence. Scaffolds based on graft copolymers bearing rigid (PLA) or flexible (PCL) side chains exhibited earlier structural disintegration during cooling and reduced network coherence, whereas the statistical P(NIPAM-co-NtBA) system maintained structural integrity over a broader temperature interval and showed greater mechanical robustness under comparable conditions. A variation of the nozzle-to-collector distance further modulated the architecture-dependent differences in the fiber morphology, porosity, and mechanical performance but did not override the dominant influence of macromolecular topology. These results establish SDT as a network-level, morphology-dependent parameter that complements LCST in describing the thermal behavior of electrospun PNIPAM-based materials.