Control of Wettability Using Flame Generated Multicomponent Nanoparticle Coatings

Pintojen kastuvuuden muokkaaminen on ollut yksi tärkeimmistä tutkimusaiheista jo vuosia. Kehitysidea vettähylkiviin ja vesihakuisiin pintoihin on tullut alun perin luonnon esimerkeistä. Yleisin tapa muokata pinnan kastumista on valmistaa pinnalle toiminnallinen nanopinnoite. Tässä työssä valmistettiin toiminnallisia nanopinnoitteita kartonki-, puu- ja lasipinnoille. Menetelmänä käytettiin nesteliekkiruiskutusta (Liquid Flame Spray, LFS), jossa nanohiukkasia muodostetaan aerosolimenetelmällä. Superhydrofobisia eli vettähylkiviä ja superhydrofiilisiä eli vesihakuisia pinnoitteita on tehty jo aiemmin nesteliekkiruiskutuksella, mutta tässä työssä tutkittiin tarkemmin pinnoitteen rakennetta ja selvitettiin mikä on minimimäärä pinnoitetta, jolla pinnan kastumista saadaan muokattua. Pinnan kastuvuus muuttui radikaalisti, vaikka pinta oli vain osittain nanohiukkasten peitossa. Pinnoitteen pysyvyys ja kulutuskestävyys ovat perinteisesti nanopinnoitteiden suurimpia ongelmia, joten ne ovat tämänkin työn tutkimusaiheita. Pinnoitteen kestävyys riippuu pääosin pinnoitteen adheesiosta ja koheesiosta. Adheesiolla tarkoitetaan pinnoitteen kiinnittymistä materiaalin pintaan ja koheesiolla hiukkasten keskinäistä kiinnipysyvyyttä nanopinnoitteessa. Tässä työssä koheesiota on pyritty parantamaan muokkaamalla nanopinnoitteen hiukkasrakennetta. Aiemmissa töissä superhydrofobinen pinnoite on saatu aikaan TiO2 nanohiukkasilla, mutta tässä työssä TiO2 nanopinnoitteen agglomeraattien kestävyyttä parannettiin lisäämällä pinnoitteeseen myös SiO2 nanohiukkasia. Tällä tavoin pinnoitteen koheesiota saatiin parannettua niin että pinnoitteen huokoisuus ja vettähylkivyys säilyivät lähes ennallaan. Tässä työssä LFS-menetelmää yhdisteltiin myös muiden pinnoitusmenetelmien kanssa. Yhdistämällä useiden pinnoitusmenetelmien hyviä puolia, saatiin aikaan superamfifobinen pinnoite eli pinnoite hylki myös muita nesteitä kuin vain vettä. LFS-menetelmällä valmistettiin huokoinen nanorakenne, jonka pintaa parannettiin plasmakäsittelyllä tai kemiallisella kaasufaasipinnoituksella (Chemical Vapor Deposition, CVD). Näillä yhdistelmäpinnoituksilla pinta saatiin hylkimään vettä, oliiviöljyä, etyleeniglykolia, diodometaania sekä n-heksadekaania. Yhdistelmäpinnoitteiden pysyvyyttä testattiin pisaratesteillä, joissa pinnoille pudotettiin tuhansia vesipisaroita. Pinnoite pysyi vahingoittumattomana, joten yhdistelmäpinnoitteella voitiin todeta olevan kohtuullisen hyvä adheesio ja koheesio.Control of wettability of surfaces has been a hot research topic for years. Developing superhydrophobic and superhydrophilic surfaces are originally inspired by nature. Most common way to control the wettability of a surface is to produce functional nanocoatings on different substrates. In this work, aerosol synthesis method Liquid Flame Spray (LFS) was used for fabricating functional nanocoatings on paperboard, wood and glass substrates. Superhydrophobic and superhydrophilic nanocoatings have been previously produced by LFS method, but in this work the structure of the nanocoating was researched more closely to gain better understanding of the stability of the coating. Furthermore, minimum amount of coating for wettability modification was determined. Wettability of a surface was significantly changed even if the surface was only partly covered with nanoparticles. Stability and wear resistance of functional nanocoatings is generally quite poor, so this was one of the research topics of this work. Stability of a coating depends on the adhesion and cohesion of the coating. Adhesion describes the interaction between a coating and a substrate and cohesion describes particle-to-particle interactions in the coating layer. This work focused on improving the cohesion of the nanocoatings by modifying the material composition of produced nanoparticles. Previously superhydrophobic TiO2 nanocoatings have been fabricated by LFS, but in this work TiO2 nanocoating was doped with SiO2, to improve the cohesion between agglomerated nanoparticles. Cohesion was successfully improved without losing the desired porosity or wetting properties. LFS method was also combined with other coating methods. By combining LFS with other coating methods, superamphiphobic behavior was achieved, meaning that nanocoated surface repelled also other liquids than water. Nanoparticle layer formed optimal, porous layer on a surface and nanoparticle layer was afterwards modified by plasma treatment or chemical vapor deposition to obtain needed chemical composition of the coating. By combining different coating methods, excellent repellency for water, olive oil, ethylene glycol (EG), diiodomethane (DIM) and n-Hexadecane was observed. Stability of multicomponent coatings was tested with thousands of water droplets and coating remained unharmed. This indicates relatively good adhesion and cohesion of the multicomponent coatings

Antimicrobial characterization of silver nanoparticle-coated surfaces by “touch test” method

Abstract: Bacterial infections, especially by antimicrobial resistant (AMR) bacteria, are an increasing problem worldwide. AMR is especially a problem with health care-associated infections due to bacteria in hospital environments being easily transferred from patient to patient and from patient to environment, and thus, solutions to prevent bacterial transmission are needed. Hand washing is an effective tool for preventing bacterial infections, but other approaches such as nanoparticle-coated surfaces are also needed. In the current study, direct and indirect liquid flame spray (LFS) method was used to produce silver nanoparticle-coated surfaces. The antimicrobial properties of these nanoparticle surfaces were evaluated with the “touch test” method against Escherichia coli and Staphylococcus aureus. It was shown in this study that in glass samples one silver nanoparticle-coating cycle can inhibit E. coli growth, whereas at least two coating cycles were needed to inhibit S. aureus growth. Silver nanoparticle-coated polyethylene (PE) and PE terephthalate samples did not inhibit bacterial growth as effectively as glass samples: three nanoparticle-coating cycles were needed to inhibit E. coli growth, and more than 30 coating cycles were needed until S. aureus growth was inhibited. To conclude, with the LFS method, it is possible to produce nanostructured large-area antibacterial surfaces which show antibacterial effect against clinically relevant pathogens. Results indicate that the use of silver nanoparticle surfaces in hospital environments could prevent health care-associated infections in vivo.</p

Characterization of flame coated nanoparticle surfaces with antibacterial properties and the heat-induced embedding in thermoplastic-coated paper

Silver nanoparticles deposited on surfaces can provide an antibacterial effect with potential uses in, for example, health-care settings. However, release of nanoparticles and their potential exposure to the environment is of concern. The current work demonstrates a continuous synthesis that simultaneously deposits silver nanoparticles onto plastic coated paper surface by utilizing the liquid flame spray (LFS) aerosol process. Heat from LFS is used to soften the thermoplastic paper surface, which enables partial and full embedding of the nanoparticles, thereby improving adhesion. The embedding is confirmed with atomic force and scanning electron microscopy, and the deposited silver amounts are quantified with X-ray photoelectron spectroscopy. The results suggest that embedding was more effective in PE-coated paper samples due to the lower glass transition temperature when compared to PET-coated paper samples. The antibacterial properties of the surfaces against E. coli and S. aureus were maintained and confirmed with a previously developed 'Touch-Test Method: The LFS process has the potential to be used for large-scale manufacturing of antibacterial surfaces with improved nanoparticle adhesion on appropriately chosen thermoplastic surfaces

Energiakylä : kylien kehittäminen kohti energiaomavaraisuutta Pohjanmaan maakunnissa : loppuraportti

fi=vertaisarvioimaton|en=nonPeerReviewed

Kodin ja koulun vaikutus varusmiespalvelukseen asennoitumiseen

Tämän tutkimuksen aiheena on kodin ja koulun vaikutus varusmiespalvelukseen asennoitumiseen. Tutkin aihetta, koska se on erittäin ajankohtainen. Asennetutkimuksia on yleisesti ottaen tehty paljon, mutta erityisesti koulun ja kodin vaikutuksesta varusmiespalvelukseen asennoitumiseen tehtyjen tutkimusten määrä on vähäinen.Tutkimusongelmina tässä tutkimuksessa ovat: Mitkä tekijät kodissa ja koulussa vaikuttavat varusmiespalvelukseen asennoitumiseen?, Miten kodin ja koulun ympäristö vaikuttaa varusmiespalvelukseen asennoitumiseen? sekä Vaikuttaako nuorten itsenäisyystietoisuus asenteisiin varusmiespalvelusta kohtaan?Aineistonkeruumenetelmänä on käytetty kyselyä. Otantamenetelmänä on ollut kokonaisotanta. Joukko, jolle kysely toteutettiin, oli Viestirykmenttiin varusmiespalvelukseen astuva 1/2011 saapumiserä kokonaisuudessaan. Tutkimusaineisto on analysoitu kvantitatiivisesti, eli määrällisellä metodilla. Tutkimustulosten analysoinnissa on käytetty apuna SPSSohjelmistoa.Tutkimuksessa todettiin, että varusmiespalvelukseen asennoitumiseen positiivisemmin todennäköisesti vaikuttavat itsenäisyystietoisuus, henkilökohtaiset ominaisuudet ja ympäristötekijät. Kodin ja koulun vaikutus henkilön itsenäisyystietoisuuden kasvatuksessa on tärkeä tekijä siihen, että henkilö saapuu suorittamaan varusmiespalvelusta paremmalla asenteella

Photocatalytic Activity of Multicompound TiO2/SiO2 Nanoparticles

Multicompound TiO2 /SiO2 nanoparticles with a diameter of 50–70 nm were generated using a liquid flame spray (LFS) nanoparticle deposition in a single flame. Here, we study the photocatalytic activity of deposited multicompound nanoparticles in gas-phase via oxidation of acetylene into carbon dioxide that gives new insight about the multicompound nanoparticle mor-phology. A small addition of SiO2 content of 0.5%, 1.0% and 3.0% significantly suppressed the photocatalytic activity by 33%, 44% and 70%, respectively, whereas 5.0% SiO2 addition completely removed the activity. This may be due to a formation of a thin passivating SiO2 layer on top of the of the TiO2 nanostructures during the LFS nanoparticle deposition. Surface wetting results support this hypothesis with a significant increase in water contact angle as the SiO2 content is increased.publishedVersionPeer reviewe

Liquid flame spray—a hydrogen-oxygen flame based method for nanoparticle synthesis and functional nanocoatings

In this review article, a specific flame spray pyrolysis method, Liquid Flame Spray (LFS), is introduced to produce nanoparticles using a coflow type hydrogen-oxygen flame utilizing pneumatically sprayed liquid precursor. This method has been widely used in several applications due to its characteristic features, from producing nanopowders and nanostructured functional coatings to colouring of art glass and generating test aerosols. These special characteristics will be described via the example applications where the LFS has been applied in the past 20 years.publishedVersionPeer reviewe

Paperboard as a substrate for biocompatible slippery liquid-infused porous surfaces

Slippery liquid-infused porous surfaces or SLIPS were first introduced in 2011 by Wong et al. who reported a bioinspired self-repairing surface with remarkable slippery properties. Generally, production of these surfaces includes fossil-based or expensive materials and processes that are available mainly in laboratory scale. In this study, slippery surfaces with sliding angles of less than 10° are obtained using fibre-based material - paperboard - that is commercially available in large-scale and also cheap compared to substrates generally used in this field. The hierarchical nanostructure that is a necessary condition for appropriate droplet mobility was obtained by the liquid flame spray method. This method is fast, scalable, has a variety of optimization parameters and can be utilized in roll-to-roll technology that is traditional in paper industry. In this work, paperboard serves not only as a substrate, but also as a reservoir for the lubricant, thus it is important to evaluate the affinity of the material for the oils and estimate the capillary movement. Therefore, Cobb and Klemm methods were used when choosing a paperboard material. In addition to synthetic oils, rapeseed oil was also utilized as a lubricant, which potentially leads to eco-friendly and recyclable slippery liquid-infused porous surfaces.publishedVersionPeer reviewe