Influence of Acrylate Monomer Structure on Fracture Morphology and Microphase Separation in <scp>UV</scp> ‐Curable <scp>PUASi</scp> Polymers

ABSTRACT In this study, UV‐curable alkoxysilane‐functionalized polyurethane acrylate (PUASi) hybrid polymers were synthesized using trimethylolpropane (TMP) as the core polyol and three acrylate monomers: 2‐hydroxyethyl methacrylate (HEMA), 2‐hydroxyethyl acrylate (HEA), and 2‐hydroxypropyl methacrylate (HPMA). The influence of acrylate monomer structure on the physicochemical and morphological properties of the resulting coatings was systematically investigated. FTIR spectroscopy confirmed the successful formation of urethane, urea, and SiOSi linkages, indicating the development of organic–inorganic hybrid networks. Deconvolution of the carbonyl region revealed distinct hydrogen bonding environments that strongly impacted phase morphology. DSC analysis showed that glass transition temperatures decreased in the order HEA &gt; HEMA &gt; HPMA, reflecting differences in hydrogen bonding strength and segmental mobility. TGA results revealed multi‐step degradation profiles, with HEMA‐ and HEA‐based polymers exhibiting greater thermal stability than HPMA‐based systems. Surface property analysis indicated that HEMA‐based coatings exhibited the highest gloss and smoothest morphology, while HEA and HPMA coatings had higher surface hardness and water contact angles. SEM imaging showed ductile fracture in HEMA‐based films, semi‐ductile fracture in HEA, and brittle fracture and a porous morphology in HPMA‐based samples.