Research
Covalent functionalization of solid cellulose
Cellulose is one of the most abundant natural polymers on earth which is widely used for production of paper and cardboard, in textile industry, drug delivery, composite materials and more. The increased environmental awareness has motivated the development of advanced biodegradable and renewable biomaterials based on cellulose, with the aim to increase its functionality and scope of use. We develop new methods for chemical modification of solid cellulose, specifically seeking processes which are modular, inexpensive, technically simple and would not damage the cellulose backbone, while providing durable functional coatings. To achieve this goal, we employ activated molecular adaptors, which possess two reactive end-groups: one affording covalent linkage between the adaptor and the cellulose backbone and the other is designed to undergo binding to functional materials. This concept allows mild reaction conditions and a use of variety of functional materials for the attachment to cellulose.
Preparation of hydrophobic cellulose
By treating cellulose based substrates such as cotton fabrics and filter paper with hydrophobic functional materials, the hydrophilic nature of cellulose can be transformed into highly- or super-hydrophobic surfaces are obtained. In addition, hydrophobicity of the surface may be tuned by dendritic amplification of the molecular adaptor affording the attachment of a higher number of functional molecules. Such amplification is feasibly performed by employing straightforward esterification and thiol-ene click chemistry. The hydrophobic smart fabrics may found useful applications as water-repellant textile and for water-oil separation.
Cotton dyeing
Current methods for cotton dyeing require use a large excess of dyes, strong chemical reagents and harsh reaction conditions, which often damage the fabric and weaken its original strength. Furthermore, physical dyeing procedures frequently leads to low color fastness, especially where dark coloration is desired. Our approach employs thiol-ene click chemistry for covalent attachment of a large scope of natural and synthetic dyes to modified cotton fabrics. Thiol-ene click reaction benefits from a wide scope thiols and alkenes, high yields, possibility for thermal or UV activation, short reaction times and easy purification. This project is performed in collaboration with the Delta ® Company.
Selective functionalization of solid cellulose using photo-patterning
Developing efficient conditions for selective introduction of functional materials to defined areas of solid cellulose would allow targeting advanced applications that require multifunctional surfaces. In general, our methodology may offer such multi-functionalization by three potential approaches: (a) modification of different surface areas with different types of molecular adaptors which can bind various functional materials in orthogonal fashion; (b) development of a molecular adaptor which can bind two (or more) different functional materials; (c) using a photomask for surface patterning. Since the incorporation of functional materials to the surface of cotton fabrics bearing molecular adaptors is performed by UV-vis light, the third approach offers a feasible route for selective coverage of the surface area of the cotton fabric, as we have demonstrated using fluorescent dyes.
Thermal and pH responsive non-woven textile
Non-wowen fabrics are engineered fabrics, which can be produced from natural and synthetic polymer fibers that are bonded together by chemical, mechanical, heat or solvent treatment.
Today non-wowen fabrics are widely used in personal hygiene products, cosmetic industry, medicine and geotextile. Smart non-woven (SNOW) fabrics represent a new generation of textile, which exhibits various properties that can be triggered by the changes in their environment, such as temperature, pH and moisture. We seek methods for surface activation of non-woven fabrics, which would allow further incorporation of functional coatings to obtain SNOW textile with desired properties for premium applications.
Incorporation of biomedical polymers into textile
Biocompatible polymers are widely used for medicinal applications as coatings or freestanding devices. We design strategies for conversion of liquid biodegradable polymers to solid materials under cross-linking conditions in the presence of textile. Such process affords preparation of fabrics that contain biomedical polymer scaffold that serves as a matrix for encapsulation of biologically active agent. The later can undergo controlled release due to slow hydrolysis of the polymer matrix under physiological conditions.
Electro-conductive organic polymers
During the past decades organic electro-conductive polymers have been widely developed due to the possibility to be integrated as active layers in flexible electronic devices such as thin film transistors, diodes and solar cells. Conductive polymers exhibit a desired combination of electrical and optical properties, ease of synthesis and solution processability.
Polythiophene and its derivatives are an important representative class of conductive polymers that form some of the most environmentally and thermally stable materials. One of the most attractive things regarding polythiophenes is the fact that their chemical and electronic properties can be engineered through synthesis and assembly. We study the preparation of thermally cross-linkable polythiophene derivatives that can be used as stabilizing components in bulk heterojunction solar cells.
Covalent modification of fabrics for water-oil separation applications
A technically simple, one-step process for the preparation of hydrophobic fabrics via covalent surface modification is presented. A small aliphatic molecule was grafted onto the surface of various types of fabrics under mild processing conditions, leading to alteration of the surface properties. The modified fabrics displayed not only hydrophobic, but also superoleophilic properties, meaning that these fabrics are ideal candidates for separation of oil-water mixtures. Separation efficiencies above 90% were achieved for the removal of common organic solvents and oils including dichloromethane, chloroform, n-hexadecane, toluene, gasoline, and olive oil from aqueous solutions. Separation efficiencies were unaffected by the exposure of the modified fabrics to elevated temperature and acidic conditions. Furthermore, all types of fabrics displayed high recyclability: Efficiency of oil-water separation did not deteriorate even after 30 cycles of oil-water separation, washing, and drying. The simplicity of the surface modification combined with the use of readily available and low-cost materials are promising characteristics for future practical applications.
Electro-conductive fibers and fabrics
text ......
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
