Prior wound dressing materials have been regarded to be only passive materials with a minimal role in the healing process, but over time the development of wound dressing from passive to active and functionalized ones was a great help in the healing process. The desirable wound dressing materials should be elastic, nontoxic, biocompatible. Moreover, it should protect the wound from side-infection, absorb the wound fluids and exudates and maintain a local moist environment, prevent the wound dryness and stimulate the cell growth rate. Our research group has also tried to fabricate new and novel natural-based wound dressing materials. In this regard, some herbal drugs have been considered to be loaded into the nanofibers produced by electrospinning method. The electrospinning method is a simple and efficient way to produce polymeric micro/nanofibers in different fibre size, porosity, surface area and fibre orientation. Highly gas permeable structure of nanofibers provides a suitable surface to absorb wound exudate and prevent microorganisms from entering the wound.
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Over the past few decades, considerable research effort has focused on creating antibacterial coatings on the surfaces of various objects such as garments and medical devices. With very recent developments in nanotechnology, elaborate and multifunctional surface coatings with precise architectural and chemical control on the nanoscale are becoming easily accessible. This offers a great opportunity to readdress the persistent challenge of obtaining effective and long-lasting antibacterial coatings. Typically, release-killing capacity is introduced to a surface by incorporating bacteria-killing chemicals such as antibiotics, phenols, and heavy metals using various methods such as spray or dip coating and hydrogel trapping. Alternatively, a surface can obtain contact bacteria-killing capacity through chemical modification with tethered bactericidal functionalities such as quaternary amine compounds, phosphonium salts, and titanium oxide particles, which are able to kill bacteria upon contact. Newly, our research group focuses on fabricating of novel antibacterial materials. |
Macroporous polymer-based materials with interconnected pores are of significant interest both fundamentally and technologically due to their physicochemical properties, functionalities and particularly high surface area to mass. One of the interesting routs to introduce porosity within polymer structures is the emulsion templating using high internal phase emulsions, internal phase occupies at least 74 vol% of the total volume of the emulsion. In which the continuous phase contains monomer along with crosslinker and the internal phase is extracted after curing. The resulting materials (named polyHIPEs) are highly porous with interconnected pore structure and mechanical integrity. Removal of the internal phase template produce large cavities of micrometre dimensions, called pores, which are interconnected through a series of small interconnects called pore throats. The pore throats are made in the areas of contact points between the neighbouring droplets in the emulsion template and allow them to communicate with each other [16,20,21]. Due to the interconnected permeable microstructure, polyHIPEs have the potential to be used in a variety of applications such as ion-exchange resins, filters, sensor materials, organic synthesis supports, chromatographic supports and particularly biomedical applications. |
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Water expandable polystyrene (WEPS) is a new generation of expanded polystyrenes, in which instead of volatile organic compounds (VOC) e.g. pentane, water is used as blowing agent. As a promising eco-friendly product and despite of several novel and creative developments in the synthesis methods, however, WEPS is still far from commercialization. This is mainly due to low expandability of WEPS beads which in turn resulted from the inability of polystyrene (PS) matrix to preserve the blowing agent (water) during storage and expansion. To cope with the problem of water loss during expansion and storage, recently, we have suggested a new synthesis route in which solid natural polymeric nanoparticles, e.g. cross-linked starch nanoparticles, cellulose nanofibrils (CNFs), starch nanocrystals (SNCs) and cellulose nanocrystals (CNCs) were used to stabilize the water microdroplets inside the polystyrene beads. Specifically, we exploited surfactant-free Pickering emulsion polymerization of styrene in water/oil/water (w/o/w) system to obtain expandable polystyrene beads. Depending on the synthesis condition and the formulation used, the as-synthesized beads contained 0-13 wt% well-dispersed water microdroplets.
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Pickering emulsions are attractive surfactant-free emulsions which are stabilized by solid particles. Pickering emulsions have been interested quite recently because of its simple formulations and higher stability. Pickering emulsions are emulsions of any type, oil-in-water (o/w), water-in-oil (w/o), oil-in-water-in-oil (o/w/o) and water-in-oil-in-water (o/w/w) emulsions stabilized by solid particles in place of surfactants. This kind of new generation of emulsions has high resistance against coalescence. Namely, if water and oil are mixed and oil droplets are formed and dispersed in the continuous phase of the water, eventually the oil droplets will coalesce to decrease the amount of energy in the system. However, if the solid particles are added to the mixture, they will adsorbed to the surface of the interface and prevent the coalescence of droplets, therefore causing the emulsion to be more stable. The Pickering emulsion polymerization gives an opportunity to produce different solid polymer particles with a versatile structure design.
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