Anti-UV and hydrophobic dual-functional coating fabrication for flame retardant polyester fabrics by surface-initiated PET RAFT technique

Inspired by the flourish of living radical polymerization (LRP), surface-initiated LPR technology shows great potential in good control and accurate tailoring of target polymer coatings. In this work, surface-initiated photoinduced electron transfer-reversible addition-fragmentation chain transfer polymerization (SI-PET-RAFT) was employed as a facile synthetic rout for the fabrication of surface-tethered polymeric brushes with anti-UV and hydrophobic properties for flame retardant polyester fabrics (FRPET). Firstly, RAFT agent 4-Cyano-4[(dodecyl sulfanyl thiocarbonyl) sulfanyl] pentanoic acid (CDTPA) was grafted onto polydopamine (PDA) deposited FRPET, followed by the controlled growth of glycidyl methacrylate (GMA) onto polyester fabrics via SI-PET-RAFT method. Finally, benzotriazole anti-UV agents were grafted as secondary functionalization. According to SEM-EDS and XPS analysis, PGMA has been immobilized successfully onto the surface of FRPET fabrics. An efficient PET RAFT polymerization of GMA with low dispersity (< 1.2), temporal control, and chain end fidelity was achieved under mild yellow light irradiation (lambda(max) = 570 nm, 4 W/m(2)). It also exhibited the feasibility of polymerization under natural sunlight and oxygen tolerance. The flame retardant, UV resistant and hydrophobic properties of the treated fabrics were investigated. In the microscale combustion calorimetry test, the peak heat release rate (PHRR) effectively decreased by 59.50%. In the cone calorimetry test, the PHRR and total heat release also reduced. The melt-dripping was eliminated in the vertical flaming test and reached V0 rating with LOI value of 28%. The UV transmittance of the fabric decreased to < 4%, meeting the standard of UV resistant fabric and the water contact angle reached 125, thus making flame retardant polyester fabric have good hydrophobicity. Besides, it also kept good durability in flame retardancy, UV shielding and water repellent. This study provides new insights into the surface engineering of photoregulated LRP techniques for multifunctional coating synthesis.