Technology Feature

Nano-encapsulation Technologies for textile and apparel industry

Prof John H Xin, Institute of Textiles & Clothing, the Hong Kong Polytechnic University, 

Polymer encapsulation is a widely applied technology having the ability of protecting the active ingredients inside the capsules and delivering the functions with the controllable release mechanisms. It is of particular interest in agriculture, food and pharmaceutical industries to produce controlled release products such as pesticides, aromatic ingredients and drugs. Many polymer capsule systems have been developed, including melamine/formalin capsules, polyamide capsules, liposome capsules, polyester capsules, polyurea and polyurethane capsules. The generally used synthesis methods include micro-gelation, emulsion polymerization, dispersion polymerization, interfacial polymerization and interfacial precipitation of amphiphilic copolymers. However, most of these capsules are designed to release active ingredients in aqueous medium, which is not suitable for textile and clothing applications where the releasing mechanism should be suitable for environments such as open air or next to skin, and the encapsulation should be durable in daily washings.   

The use of encapsulation and controlled release technology in textile and apparel areas represents a new direction for the functional finishing. It provides new and substantial benefits to consumers. Although some finishing products based on microcapsules have appeared on the market, there are always thorny problems hindering their use and acceptance. These problems include high cost, low encapsulation efficiency, heavy loss of ingredients during the processing stage, poor washing fastness due to the large particle sizes and weak adhesion to fibres, and skin-irritating side-effect due to the hazardous chemical residues.              

Recently, in Institute of Textiles & Clothing, the Hong Kong Polytechnic University, new functional products based on novel nano-encapsulation systems were developed by a research team led by Prof John H Xin. These systems include Fresh aroma™ -  a new fragrance delivery system, Vitawear™ - a new fabric skincare system, and Anti-Mos™ - a new high efficacy skin-kind anti-mosquito system. These new systems have high encapsulation efficiency, and employed mainly skin/bio-compatible natural materials as shells. The nanocapsules having high affinity to fibres, together with their small size and softness, facilitate an improved washing fastness. The release of the ingredients can also be controlled to facilitate a long lasting effect.  

Further development works for the nano-encapsulation technologies of both organic and inorganic particles are still on-going in Prof. Xin’s group so as to achieve a wider range of functions in the areas of controllable optical, electrical, thermal, mechanical, magnetic, and catalytic properties on textile and apparel products.

Fresh aroma™ represents a new latex technology to synthesize aromatic capsules applicable to apparel, decorative textiles, carpets, artificial flowers, etc. These polymer capsules prepared by in-situ miniemulsion polymerization are very stable and having good affinity to the textile fibres. It also provides a long lasting in-air delivery of fresh fragrance.

Vitawear™ represents a brand new nano-biotechnology providing vitamins to skin directly from clothing. Lipophilic vitamins are encapsulated by a supermolecular dynamer system, while hydrophilic vitamins are delivered by a temperature-sensitive nano-gel. Products finished with this technology possess the skincare functions such as preventing skin wrinkle and aging, improving skin whiteness, scavenging the free-radicals and improving skin elasticity.  

Anti-Mos™ system provides multi-functions: anti-mosquito, anti-bacteria, and anti-dust mite. Anti-Mos™ utilized the chemical technology based on heterophase copolymerization with in-situ self-assembly. Besides insecticide, other oily functional reagents can be efficiently encapsulated using this novel system. When applied on textile fibers, a colorless transparent soft thin layer was formed on fiber surface. The thin layer assembled from nano-capsules shows high bio-activity and good durability.              


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