Development of Thermoresponsive PNIPAm‐PET Composite Membranes Using Solvent‐ and Microwave‐Assisted Techniques With Potential Applications in Smart Packaging

ABSTRACT This study presents a simple and scalable process for fabricating thermoresponsive membranes by physically coating poly( N ‐isopropyl acrylamide) (PNIPAm) onto a track‐etched polyethylene terephthalate (PET) substrate. Dimethyl sulfoxide (DMSO), used as a swelling agent, enhanced monomer penetration into PET pores, while microwave‐assisted polymerization reduced fabrication time to 30 min, achieving uniform polymer deposition. Key parameters—microwave power (300–850 W), irradiation time (5–15 min), and crosslinker addition—were systematically studied. Weight gain (WG) increased by 195%, with crosslinker addition further enhancing incorporation fourfold. Vacuum‐assisted techniques improved PNIPAm coverage, confirmed by scanning electron microscopy (SEM). Fourier‐transform infrared spectroscopy (FT‐IR) verified PNIPAm incorporation, with peak intensity correlating to WG. The membrane exhibited thermoresponsive hydrophilic‐hydrophobic transitions, with contact angles shifting from 40°–67° (below 25°C) to 56°–72.8° (above 40°C), enabling “on–off” permeability control. In a shelf‐life simulation, membranes fabricated at 600 W and 15 min irradiation effectively regulated O 2 and CO 2 concentrations in asparagus packaging, extending shelf life. These results demonstrate the potential of this scalable fabrication method for smart packaging and industrial applications.