Catalytic deposition of polydopamine and nanoclay bi-layer formation on UHMWPE fibers for enhanced performance in fiber-reinforced cementitious composites (FRCC)

The Ultra-High Molecular Weight Polyethylene (UHMWPE) fibers are significantly considered for Fiber-Reinforced Cementitious Composites (FRCC) development due to their excellent tensile strength and elastic modulus. However, due to the hydrophobic nature of the fibers, strong fiber-matrix interfacial bonding is still challenging. Mussel-inspired polydopamine coating has gained attention for its ability to preserve the fiber’s tensile strength while also serving as a platform for bi-layer applications. Polymerization through auto-oxidation of dopamine monomer proceeds very slowly, taking 12 to 24 h minimum for an efficient film formation. This study suggests an expeditious and feasible strategy to convert hydrophobic UHMWPE fibers into hydrophilic ones using catalytic polydopamine deposition mechanism. The reaction time was reduced by 75–88% while still achieving the desired surface properties. Following, a nanoclay coating procedure was developed for modified fibers. Water contact angle, SEM-EDX, XPS, and FTIR analysis were conducted, revealing enhanced wettability, varied surface morphology, and the presence of new functional groups in the modified fibers, respectively. The FRCC using coated fibers showed improved mechanical performance under tensile loads in terms of first-cracking strength, ultimate tensile strength, and strain capacity compared to uncoated fibers FRCC. Thus, quick strategies were explored for PDA and nanoclay coated surfaces considering strong fiber-matrix bridging in FRCC.