POS2-1422
Reconfigurable Network Using TBEMA-IEM Crosslinker in 1K Waterborne Polyurethane Coating
Topic
S2. High-End Characterization/Polymer Physics/Properties
When and Where
Sep 29, 2026
08:30 - 09:30
Room 301 (Grand Ballroom)
Session Chairs
Hae Jung SON
Boseok KANG
Presenter(s)
Youngjae Cheon (Pusan National University)
Co-Author(s)
Abstract
Waterborne coatings are environmentally favorable alternatives to solvent-borne systems owing to low VOC emissions. Internal crosslinkers are widely used to secure colloidal stability and build a network within latex particles; however, such permanent networks restrict interdiffusion during film formation, leaving unhealed boundaries that remain the weakest regions of the film. Here, a one-component waterborne acrylic–polyurethane system incorporating a TBEMA-IEM hindered-urea latent crosslinker and a reactive surfactant was developed to overcome this trade-off. The emulsions showed stable, uniform ~100 nm particles with a low PDI (< 0.05). Unlike the permanent crosslinker EGDMA, TBEMA-IEM forms a reconfigurable network that preserves the intraparticle network during polymerization yet reorganizes upon heating. NMR analysis of the thermally treated monomers confirmed that the TBEMA-IEM hindered urea dissociates faster than the blocked isocyanate MOI-BP. This early dissociation transiently lowers the crosslink density, facilitating chain mobility and interdiffusion across the original particle boundaries, as evidenced by a pyrene-derived fluorescence probe. The regenerated isocyanate then reacts with hydroxyl groups of HEMA, locking the interdiffused chains into urethane linkages that bridge neighboring particles. This dissociation–diffusion–relocking pathway establishes a spatially uniform network in which intra- and interparticle crosslinks are seamlessly integrated. Consequently, TBEMA-IEM outperformed EGDMA across thermal, viscoelastic, and mechanical analyses, and showed lower surface roughness, higher transparency, and superior gloss, reflecting complete particle coalescence and healed boundaries. These findings show that a reconfigurable hindered-urea network unifies intra- and interparticle crosslinking, enabling waterborne coatings that achieve high-quality film formation.
