Roy M. Broughton

N-halamine biocidal coatings via a layer-by-layer assembly technique.

Two N-halamine copolymer precursors, poly(2,2,6,6-tetramethyl-4-piperidyl methacrylate-co-acrylic acid potassium salt) and poly(2,2,6,6-tetramethyl-4-piperidyl methacrylate-co-trimethyl-2-methacryloxyethylammonium chloride) have been synthesized and successfully coated onto cotton fabric via a layer-by-layer (LbL) assembly technique. A multilayer thin film was deposited onto the fiber surfaces by alternative exposure to polyelectrolyte solutions. The coating was rendered biocidal by a dilute household bleach treatment. The biocidal efficacies of tested swatches composed of treated fibers were evaluated against Staphylococcus aureus and Escherichia coli. It was determined that chlorinated samples inactivated both S. aureus and E. coli O157:H7 within 15 min of contact time, whereas the unchlorinated control samples did not exhibit significant biocidal activities. Stabilities of the coatings toward washing and ultraviolet light exposure have also been studied. It was found that the stability toward washing was superior, whereas the UVA light stability was moderate compared to previously studied N-halamine moieties. The layer-by-layer assembly technique can be used to attach N-halamine precursor polymers onto cellulose surfaces without using covalently bonding tethering groups which limit the structure designs. In addition, ionic precursors are very soluble in water, thus promising for biocidal coatings without the use of organic solvents.

Polymeric antimicrobial N-halamine epoxides.

A new N-halamine copolymer has been prepared, characterized, and evaluated for antimicrobial efficacy, stability toward hydrolyses, and stability toward UVA degradation when covalently bound to cellulose fibers. A copolymer of 3-chloro-2-hydroxypropylmethacrylate and glycidyl methacrylate was coated onto cotton, and, after curing, was treated with an aqueous solution containing the potassium salt of 5,5-dimethylhydantoin to form a coating which became antimicrobial upon exposure to househod bleach (sodium hypochlorite). The coating inactivated S. aureus and E. coli O157:H7 within minutes of contact time and was quite stable toward washing and UVA photodegradation.

Novel n-halamine siloxane monomers and polymers for preparing biocidal coatings

SummariesPrecursor N-halamine siloxane monomers and polymers have been prepared for the purpose of functionalising the surfaces of materials in order to render them biocidal upon exposure to oxidative halogen solutions. The biocidal function can be imparted to the N-halamine moiety either before or after siloxane bonding or adhesion to the surface or material. The biocidal surfaces and materials can then be used to inactivate pathogenic micro-organisms such as bacteria, fungi and yeasts, as well as virus particles, which can cause infectious diseases, and those micro-organisms which cause noxious odours and unpleasant colouring such as mildew. Examples of surfaces and materials which can be rendered biocidal with the N-halamine siloxanes include cellulose, synthetic fibres, ceramics, plastics, polyurethanes and metals. Preparation procedures and some biocidal efficacy data on paper, cotton and polyurethane paint are discussed.RésuméDes monomères et des polymères précurseurs à N-halamine siloxane ont été préparés afin de fonctionnaliser la surface des matériaux pour les rendre biocides quand ils sont exposés à des solutions oxydatives à l’halogène. L’addition de la fonction biocide au groupe caractéristique N-halamine peut précéder ou suivre la liaison du siloxane comme elle peut précéder ou suivre l’adhésion à la surface ou au matériau. Les surfaces biocides et les matériaux peuvent alors être utilisées pour inactiver des micro-organismes pathogéniques inactifs tels que les bactéries, les champignons, les levures, et les particules de virus, qui peuvent provoquer des maladies infectieuses, aussi bien que ces microorganismes, tels que la moisissure, qui créent des odeurs nocives et la coloration désagréable. Des exemples de surfaces et de matériaux qui peuvent être traités des N-halamine siloxanes pour les rendre biocides comprennent la cellulose, les fibres synthétiques, les céramiques, les plastiques, les polyuréthanes, et les métaux. Les procédés de préparation et quelques données dans le domaine de l’efficacité biocide sur le papier, le coton, et la peinture polyuréthane sont discutés.ZusammenfassungN-Halaminsiloxanmonomere und -polymere wurden darauf vorbereitel, duch die Aussetzung an oxidierende Halogenlösungen Oberflächen eine disinfizierende Wirkung zu verleihen. Die Biozid-Wirkung kann der N-Halaminhälfte entweder vor oder nach der Bildung der Siloxanverbindung oder nach Auftragung des Anstriches auf eine Oberfläche verliehen werden. Die Biozidwirkung der Oberfläche neutralisiert sowohl Pathogene wie Bakterien, Pilze, Hefen oder Viren, als auch geruchs- und fleckbildende Mikroorganismen wie Schimmelpilze. Zu den Oberflächen, die mit N-Halaminsiloxan-Biozidanstrichen behandelt werden können, gehören Zellulosen, Synthetik-Fasern, Keramik, Plastik, Polyurethane und Metalle. Wir legen ausserdem die Herstellungsmethoden und Daten zur Effektivität der Biozide auf Papier, Baumwolle und Polyurethananstrichen dar.

N-halamine biocidal coatings

Novel N-halamine siloxane and epoxide coatings are described. The coatings can be rendered biocidal by exposure to dilute bleach. Once the bound chlorine is lost from the coatings, it can be regenerated by further exposure to dilute bleach. Synthetic schemes and biocidal efficacy data are presented. The stabilities of the bound chlorine on the surfaces are also addressed. Substrates employed include sand, textiles, and paint. Potential uses for the technology are discussed.

N-halamine copolymers for use in antimicrobial paints.

A series of copolymers containing units of a novel hydantoinylacrylamide and the sodium salt of 2-(acrylamido)-2-methylpropanesulfonic acid have been synthesized. The homopolymer of the hydantoinylacrylamide compound was insoluble in water, while the copolymers with the sulfonic acid sodium salt were water-dispersible/soluble, with the solution becoming completely transparent when the feed ratio for the copolymer contained 7 parts of the hydantoin moiety to 3 parts of the sodium sulfonate moiety. The polymers were added into a commercial water-based latex paint, and upon drying, the painted surfaces treated with the water-miscible copolymers were rendered antimicrobial following chlorination with dilute household bleach. The chlorinated homopolymer failed to provide an antimicrobial property for the paint because of its tendency to isolate into aggregates in the paint, while the completely miscible copolymers were capable of 6-log inactivation of Staphylococcus aureus and Escherichia coli O157:H7 within 5 min of contact time.

A Statistical Approach for Determining the Technological Value of Cotton Using HVI Fiber Properties

A statistical approach for determining the technological value of a variety of cotton is presented. The approach suggests that the market value of cotton should correspond to its technological value in a particular manufacturing system; that is, the value of a bale of cotton should be determined based on its expected performance in the textile mill and the yarn quality obtained from it. A model relating fiber to yarn properties is a basic requirement for implementing the approach. The procedures used in this approach include developing a multiple regression model relating HVI fiber properties to the desired quality parameter of yarn (skein break factor), determining the percent relative contribution of a fiber property with respect to skein break factor, selecting a reference set of HVI fiber properties, determining a difference factor of the difference in value between fiber properties of a particular variety and the reference set, and finally, developing a premium/discount formula. The main feature of the approach is its flexibility in accommodating different fiber properties and yarns of different counts produced on different spinning systems.

Mechanism of Yarn Failure

The importance of interfiber friction in determining yarn strength has been acknowledged by several authors. Studies of the effect of friction on yarn strength were often based on determining the influence of twist level, a structural factor, to change the level of friction. To our knowledge, no study is available in which varying fiber frictional characteristics are introduced into a constant yarn structure (i.e., the same twist, fiber type, fiber length, etc.). This effect has been accomplished through a surface treatment that changes the level of interfiber friction, and subsequent yarn testing provides useful and interesting information about how fiber interaction contributes to yarn strength. The results presented here show that interfiber friction can (under certain circumstances) be the dominant factor in determining the tensile properties of a ring spun staple yarn. Friction and yarn strength results show that moderate changes in the interfiber friction can produce large changes in yarn strength. We suggest that interfiber friction should receive more attention as a determinant of yarn properties, particularly strength.

Acyclic N-Halamine Polymeric Biocidal Films

Low concentrations of acyclic amide monomers, methacrylamide (MAM) and acrylamide (AM), were copolymerized with vinyl acetate (VAc). No significant differences between the synthesized copolymers and poly(VAc) were seen by 1H-NMR, FTIR, and DSC analysis. Biocidal films, formed by coating the copolymers onto polyester transparency slides and polyester fabric swatches, were chlorinated by exposure to sodium hypochlorite solutions. Both S. aureus and E. coli O157: H7 were completely inactivated within 1 min on the transparency slides and polyester fabric swatches derived from poly(VAc-co-MAM). The chlorine on the films was stable under UVA irradiation and the surfaces were rechargeable upon chlorine loss.

Preparation of alginate–chitosan fibers with potential biomedical applications

The preparation of alginate-chitosan fibers, through wet spinning technique, as well as the study of their properties as a function of chitosans molecular weight and retention time in the coagulation bath, is presented and discussed in this work. Scanning electron microscopy (SEM) revealed that the fibers presented irregular and rough surfaces, with a grooved and heavily striated morphology distributed throughout the structure. Dynamic mechanical analysis (DMA) showed that, with the exception of elongation at break, the incorporation of chitosan into the fibers improved their tensile properties. The in vitro release profile of sulfathiazole as a function of chitosans molecular weight indicated that the fibers are viable carriers of drugs. Kinetic models showed that the release of the model drug is first-order, and the release mechanism is governed by the Korsmeyer-Peppas model. Likewise, fibers loaded with sulfathiazole showed excellent inhibition of Escherichia coli growth after an incubation time of 24h at 37 °C.

Evaluating Staple Fiber Processing Propensity Part I: Processing Propensity of Cotton Fibers

In this study, we present a novel approach to simulate and characterize the behavior of fibers during processing using a modified version of the familiar rotor ring system. With this modification, we attempt to create an area approximately resembling the carding zone and measure the energy required to shear the fibers in this area. We then use the energy readings to provide an index of fiber processing propensity. Such an index is believed to be a function of combined fiber cohesion and fiber resiliency. In addition to the rotor ring, we present corresponding results from other independent techniques such as NIR wax analysis and sliver cohesion. The most important finding of this part of the study is that deterioration in the quality of yarns and fabrics should not be rationalized only on the basis of standard fiber properties (such as length, fine ness, and strength) and that measures of processing propensity, wax content, and sur face cohesion provide a complete picture of fiber processibility and its impact on end product quality.