Durable Non-Fluorine Water-Repellent Fabric Finishing: Surface Treatment Using Silica Nanoparticulates and Mixed Silanes

Abstract

Due to the cost of processing, materials, and environmental and human hazards, alternatives to fluorine-containing water-repellent finishes have begun to be heavily investigated. One type of chemistry, i.e. surface modification using silica nanoparticles and mixed silanes has recently become of particular interest in the scientific community.

100% cotton fabrics were treated with a combination of silica nanoparticles, silane hydrophobes (such as alkyltrialkoxysilanes), and silane crosslinkers (such as tetraethoxysilane). Fabric samples were prepared using a laboratory-scale dip-dry-cure process. After coating, the performance of the samples was evaluated using a contact angle goniometer. A number of the best performing samples were selected for further investigation, involving durability to laundering and crocking.

Results of the work show that surface modification using silica nanoparticles (both hydrophilic and hydrophobic) and mixed silanes was successful; the contact angle values of finished but unwashed samples ranged between 129° and 144°. Fabric samples made using the silane crosslinker tetramethoxysilane, silane hydrophobe ndecyltriethoxysilane, and silica nanoparticles had the highest water contact angle of all samples tested before laundering and crocking.

Fabric samples had varying levels of performance after being subjected to laundering and crocking. There was a very notable difference in samples after laundering that were allowed to air dry at laboratory conditions to those that was heat dried at the temperature at which the samples were cured. All samples prepared with the crosslinker bis(triethoxysilyl)ethane showed the best durability to laundering, especially those using solutions that were prepared using an ultrasonic probe. The most durable sample was prepared with an ultrasonicated solution of bis(triethoxysilyl)ethane, noctyltrimethoxysilane, and Aerosil® 90 fumed silica. These samples had an average contact angle of 129.7° before washing (AATCC-type accelerated laundering) and heatdrying and a contact angle of 123.1° after washing and heat-drying. This 94.9% recovery in contact angle shows a lot of promise in the technology that is the focus of this research.