Admicellar polymerization of styrene on cotton

Admicellar polymerization is a surfactant mediated technique used to modify substrate surface by forming the polymer thin film on substrate surface. To modify the cotton surface to obtain hydrophobic cotton, admicellar polymerization was used in this work. Polystyrene film was formed on cotton surface by the reaction inside the admicelle of linear alkylbenzenesulfonate (LAS) following the three-main steps consisting of admicelle formation, monomer adsolubilization, and polymerization. The optimum conditions of each important parameter for the production of hydrophobic cotton were obtained. The appropriate condition of LAS used was 1,000 uM. The optimum ratios of LAS:styrene and persulfate initiator:styrene were 1:5 and 1:1, respectively. The modified surface and coated film were 1:5 and 1:1, respectively. The modified surface and coated film were characterized to confirm that polystyrene was formed on cotton surface by using Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and scanning electron microscopy (SEM). The organic initiator using 2,2-azobisisobutronitruile AIBN) was also comparatively studied. The optimum ratios of AIBN:styrene was 0.1:1 which was lower than persulfate. The hydrophobicity of all treated cotton was confirmed by the drop test. The wettability method was applied to study the surface characteristic of samples. In admicellar-treated cotton samples prepared at the optimum conditions, the contact angle calculated from the results of Welhelmy test was higher than 60℃ and it increased as the amount of styrene and initiator increased. The treated cotton absorbed only 3% of water retained by the bare cotton. Water transport into the yarns was described by capillary force and radial flow between the fibers along the length. The surface of treated cotton fiber was studied by atomic force microscopy (AFM). It showed that cotton surface coated by admicellar polymerization technique did not differ much from that of bare cotton indicating that the coated film was very thin. To improve the quality of the coated film, cross-linking agent, divinyl benzene (DVB), was used to form network polystyrene film. X-ray photoelectron spectroscopy (XPS) characterization and wettability test showed that DVB affected both film formation and hydrophobicity of the coated cotton. The appropriate amount of DVB was found to be in the range of 1-2% of total monomer.