Advanced Wound Care Adhesives with New Functional Properties

Valeria Chiaula

Research output: Book/ReportPh.D. thesis

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Abstract

An increasing number of patients, globally, suffers from chronic wounds as a consequence of diabetes or other chronic diseases that may interfere with a correct wound healing. When not effectively treated, chronic wounds can lead to significant disability, limb amputation, and increased mortality. In addition, the outbreak of severe bacterial infections is one of the major complications related with chronic wounds. Such conditions affect patients’ life not only physically, but also socially, since patients often experience depression, fear, and social isolation. Moreover, chronic wounds management economically affects the medical system due to the high costs of medical treatments. Therefore, advanced wound care solutions, which effectively promote wound healing while preventing bacterial infections, are sought after.

Pressure sensitive adhesives (PSAs) are a broad class of materials used in several applications. For wound care applications, PSAs are required to be soft, viscoelastic solids. Among PSA materials, silicone adhesives are particularly sought after amongst wound care industry. Silicone adhesives possess gentle skin adhesion properties along with other unique properties of silicones, such as flexibility, chemical inertness and biocompatibility. In addition, silicone adhesives are considered atraumatic since their removal from the skin is easy and residue-free. In general, skin adhesives should allow for moisture transmission at the skin-adhesive interface to avoid skin maceration. Due to large mobility of the polymer chains, silicone adhesives possess high oxygen permeability and water vapor transmission rate (WVTR). However, due to their inherent hydrophobicity, current silicone adhesives for wound care are challenged when it comes to fluid handling. In addition, as silicones attach poorly to moist surfaces, basic perspiration from the user’s skin can cause the silicone to lose its adhesive properties, resulting in undesired failure of the skin adhesive.

Therefore, in the first part of the project, the main goal is to improve both permeability and water absorption of silicone adhesives. This is achieved by the incorporation of emulsified glycerol into silicone adhesives, developing a novel, industrially relevant glycerol-silicone hybrid adhesive. The glycerol-silicone adhesives are created simply by providing high shear forces to mixtures of glycerol and silicone adhesive premix. This allows the formation of physically stable glycerol-insilicone emulsions, which upon cross-linking of the silicone phase, form free-standing two-phase adhesives. It is demonstrated that the incorporation of glycerol into silicone adhesives significantly improves both the permeability and the water absorption, without compromising the mechanical properties of adhesives and also peel and tack. This is mainly due to the so-called solid stiffening effect given by the glycerol droplets as a result of their interfacial energies. In addition, the adhesive performance during realistic perspiration conditions is investigated.

In the final phase of this project, the incorporation of the antiseptic drug octenidine viacyclodextrins into glycerol-silicone adhesive, its release and antimicrobial properties are investigated. The chemical structure of octenidine presents long alkyl chains and two amine groups. As the crosslinking of glycerol-silicone adhesives occurs via hydrosilylation reaction, the amine groups constitute a threat for the sensitive platinum (Pt) catalyst and thus inhibits the reaction. It is shown that cyclodextrins suppress the interference of octenidine with the Pt Catalyst, likely through the formation of an inclusion complex between octenidine and cyclodextrins. A patent was recently filed on this new technology. 
Original languageEnglish
Place of PublicationKgs. Lyngby
PublisherTechnical University of Denmark
Number of pages140
Publication statusPublished - 2020

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