Environmentally controlled emulsion electrospinning for the encapsulation of temperature-sensitive compounds

The introduction of highly volatile fragrances within polymeric nano-scaled fibers is a promising route for efficient and simple encapsulation of temperature-sensitive materials. This work describes the investigation of selected parameters influencing the electrospinning of emulsions of poly(vinyl alcohol) (PVA) and (R)-(+) limonene or hexadecane. Thereby the influence of environmental parameters such as temperature and relative humidity on the fiber structure and encapsulation efficiency (EE) of the fragrance is demonstrated. For that purpose, the electrospinning process was carried out in a climatic cabin in which temperature and relative humidity were controlled. Studied temperatures ranged from 8 to 24°C and relative humidity varied between 55 and 85%. The influence of temperature was dependent on the PVA concentration in the emulsion. The relative humidity influenced both the obtained fiber morphology and fragrance EE to a higher extent than the temperature due to the hydrophilic nature of the PVA. This study is of importance when considering the use of emulsion electrospinning for encapsulation purposes

Environmentally Controlled Electrospinning

Electrospinning is a versatile technique for various applications. This process is influenced by temperature and relative humidity that impact the spinnability and morphology of the electrospun fiber. However, electrospinning in climatized conditions is scarcely reported in the literature. This study aims at filling this gap in the case of emulsion electrospinning where the fiber morphology and the encapsulation efficiency of the dispersed phase within the polymer of the continuous phase will be influenced by the environmental parameters. The electrospinning of thermo-responsive polymer solutions was also considered. Indeed, the spinning of fibers from polymer solutions is also influenced by environmental parameter since the polymer chain changes configuration (collapse of polymer chains) and behavior (hydrophilic/hydrophobic) when the solution temperature becomes higher (or lower) than a critical solubility temperature. Fiber surface chemistry and morphology changed. Parallel projects focused on the electrospinning of emulsions for different applications and having complex architectures

Fragrance encapsulation in polymeric matrices by emulsion electrospinning

We present the successful application of emulsion electrospinning for the encapsulation of a model for highly volatile fragrances, namely (R)-(+)-limonene in a poly(vinyl alcohol) (PVA) fibrous matrix. The influence of the emulsion formulation and of its colloidal properties on the fiber morphology, as well as on the limonene encapsulation efficiency, is described. The release profile of the fragrance from the electrospun nanofibers over a fifteen days range shows that this type of nanofibrous matrices with a high fragrance loading capacity is of great potential for applications in various fields, such as cosmetics or food packaging

Environmentally controlled emulsion electrospinning for the encapsulation of temperature-sensitive compounds

The introduction of highly volatile fragrances within polymeric nano-scaled fibers is a promising route for efficient and simple encapsulation of temperature-sensitive materials. This work describes the investigation of selected parameters influencing the electrospinning of emulsions of poly(vinyl alcohol) (PVA) and (R)-(+) limonene or hexadecane. Thereby the influence of environmental parameters such as temperature and relative humidity on the fiber structure and encapsulation efficiency (EE) of the fragrance is demonstrated. For that purpose, the electrospinning process was carried out in a climatic cabin in which temperature and relative humidity were controlled. Studied temperatures ranged from 8 to 24 °C and relative humidity varied between 55 and 85 %. The influence of temperature was dependent on the PVA concentration in the emulsion. The relative humidity influenced both the obtained fiber morphology and fragrance EE to a higher extent than the temperature due to the hydrophilic nature of the PVA. This study is of importance when considering the use of emulsion electrospinning for encapsulation purposes

Coumarin meets Fluorescein : a Förster Resonance Energy Transfer enhanced Ammonia Gas Sensor

This study focuses on the development of an optical ammonia gas sensor, the sensing mechanism of which is based on Förster resonance energy transfer (FRET) between coumarin and fluorescein. The dyes were immobilized into an organically modified silicate matrix during polymerizing methyltriethoxysilane with trifluoropropyltrimethoxysilane on a poly(methyl methacrylate) substrate. The resulting dye-doped xerogel films were exposed to different gaseous ammonia concentrations. A logarithmic decrease of the coumarin fluorescence emission band at 442 nm was observed with increasing gaseous ammonia concentrations, which was due to enhanced FRET between coumarin and fluorescein. The coumarin/fluorescein composition was optimized in order to obtain the best ammonia sensitivity. First experiments in a flow cell gas sensor setup demonstrated a sensitive and reversible response to gaseous ammonia