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Item type:Publication, Access status: with files , Spray coating of cellulose aerogel particles in a miniaturized spouted bed(Springer, 2021-07-04); ; ; ; Aim of this work is to apply protective and homogeneous shellac coating layers on the surface of hydrophilic open-pore cellulose aerogel particles with low densities ≤ 0.1 g/cm3 and high specific surface areas in the range of ~ 400–450 m2/g while keeping the aerogels’ microstructure intact during processing. For this purpose, an innovative miniaturized spouted bed setup was used. Successful process settings for application of enclosed films on aerogel surfaces without intrusion of coating material into the pores were determined. Precise control of coating layer thickness in the range of 10–50 µm was achieved due to variation of coating solution amount without agglomeration and clogging events occurring during processing. Comparison of bulk densities and specific surface areas before and after coating proved the intactness of the porous structure. Coating of particles loaded with vanillin led to controlled release, enhancing release half-life times from 20 to 1600 min. Overall, a successful strategy for coating of organic low-density aerogels was developed.Publicationtype: Journal ArticleScopus© Citations 13 218 261 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Novel technique for measurement of coating layer thickness of fine and porous particles using focused ion beam(2019-02-01); ; ; ; A novel technique for the measurement of the coating layer thickness of fine particles was developed in this work based on cross-sectioning of micrometre-sized single coated particles using focused ion beam (FIB) milling. This technique was tested on two batches of aerogel particles coated with thin coatings in a spouted bed. The FIB milling procedure consisted of two steps. First, the desired part of the coated particle was removed using a high ion beam current. The resulting cross-sectioned area was then polished using a lower ion beam current to make the cross-section clearly visible. The FIB milling process was controlled with simultaneous scanning electron microscopy (SEM). Afterwards, the coating layer thickness was evaluated using the SEM images. The coating layer was successfully applied on the porous aerogel microparticles in the spouted bed. The coating uniformity of the highly porous particles increased with increasing sprayed coating solution amount, with up to 91% of the particle pores being covered. The FIB-cross-sectioning technique using an ion beam of 2.50 nA for the first milling and 0.43 nA for polishing of the surface resulted in successful generation of cross-sections of representative particles with a visible particle core and coating layer. A coating layer thickness of approximately 700 nm was achieved on particles with sizes of below 45 μm.Publicationtype: Journal Article262 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Functionalization of aerogel particles by coating in a spouted bed(2018-04-22); ; ; Aerogels are porous and light-weighting materials with high specific surface area. Due to their properties they have been investigated as carriers of active ingredients. However, open pore structure limits their application because of changing their structure when they are exposed to liquids. Therefore, there is a protective layer on the surface of the aerogels needed, which preserves loaded drug or enables storage in liquid containing media. Furthermore, the knowledge of thickness of the applied coating layer is essential in order to predict the storage or release behavior. In this work a novel technique for measurement of coating layer thickness of fine particles is presented. This method is based on cross-sectioning of single coated particles in micrometer size range with focused ion beam (FIB). This technique has been tested on two batches of produced aerogel particles coated with thin coating layers in a spouted bed.Publicationtype: Conference Paper172 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Coating of fine Aerogel particles using spouted bed technologyAerogels are porous and light-weighting materials with high inner surface area. Their properties enable to use them in many fields, e.g. as acoustic and thermal insulation materials, catalyst, adsorber or drug carriers. However, open pore structure does not allow their application in different areas because of change of the structure caused by liquid-contact. Therefore there is a protective layer on their surface needed, which provides new fields of application, e.g. in food products. In this work coating of the protein-based aerogel microspheres (dP < 100 μm) with shellac using spouted bed technology was performed. This method enables applying of dense, uniform and thin coating layer on fine particles. To improve the uniformity of the coating layer the specific surface area before and after the coating procedure was measured and showed clear decrease after longest coating time. To investigate the behavior ofaerogels in water containing medias the particles were exposed to water drops using sessile drop protocol. The coating protects the aerogel particles from water influence.Publicationtype: Conference Paper168 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Coating of protein-based aerogels using spouted-bed technology(Wiley-VCH, 2016-08-29); ; ; ; Publicationtype: Journal Article102