Low-surface-energy materials based on polybenzoxazines for surface modification of textiles

Abstract

The benzoxazine monomers, 3-tert-butyl-3,4-dihydro-8-allyl-2H-1,3-benzoxazine (Benz-m) and 2,2-bis(3-methyl-3,4-dihydro-2H-1,3-benzoxazinyl) propane (Benz-b) were synthesized successfully using Mannich reaction. The formation of the monomer was confirmed by 1H NMR and FTIR spectroscopy. Both the monomers were coated onto cotton fabric and the fabric samples were then dried at 60°C and cured at 120°C for varying time period. During the curing process, monomer was converted to polybenzoxazine by ring-opening polymerization of oxazine ring. In the Raman spectra, presence of the characteristic absorption bands due to benzoxazine structure at 952, at 1037 and at 1348 cm−1 even after curing at 120°C for 2 h, suggested incomplete ring opening of benzoxazine to form polybenzoxazine. Also, the lack of durability of the finish to washing appears be due to the mild conditions of curing. Therefore, the application of Benz-b monomer was investigated on polyester (PET) fabric, which could be subjected to higher temperature however for shorter duration. The water and oil (ethylene glycol) repellency was measured to determine the hydrophobicity and oleophobicity of the finish on PET fabric. It was found that there was a marked improvement in the durability to laundry when compared with the treated cotton samples. This study provides a unique and easy method to prepare a low-surface-energy material through a simple thermal treatment procedure without using fluoro polymers or silicones.