Immobilization of optical chemical sensors on plastic surfaces

U ovom radu ispitano je mogu li se na nosače (pločice) načinjene od komercijalnih polimernih materijala, koji se koriste u aditivnoj proizvodnji, integrirati optički kemijski senzori u obliku tankih filmova unutar kojih je imobiliziran pH indikator. Cilj ovog rada je dobiti što više korisnih informacija kako bi se razvio film koji bi se mogao koristiti za oblaganje kanala mikroreaktora izrađenih aditivnom proizvodnjom. Ispitano je ukupno osam različitih polimernih materijala te staklo koje se u praksi učestalo koristi kao nosač ovakvog tipa kemijskih senzora. Korišteno je ukupno pet različitih tankih filmova, te tri pH indikatora. Prvi film (NB/PVC) dobiven je otapanjem poli(vinil-klorida) (PVC) u tetrahidrofuranu (THF) uz dodatak lipofiliziranog Nile blue (NB) indikatora. Ostala četiri filma dobivena su sol-gel metodom, pri čemu je za tri filma korišten indikator bromkrezol zeleno, a u zadnjem filmu je korišteno metil crveno. Za dobivanje sol-gel koktela korištena su tri različita silanska prekursora (tetraetoksisilan TEOS, glicidoksipropiltrimetoksisilan GLYMO i feniltrimetoksisilan FTMS) u različitim omjerima kako bi se ispitao utjecaj njihovog odabira na svojstva dobivenih filmova. Pripremljene sol-gel otopine (kokteli) nanesene su na pločice spin-coating tehnikom. Od svih ispitanih materijala TOUGH (smjesa polietilena i polipropilena) se pokazao najlošijim za ovu primjenu jer su se svi ispitani filmovi vrlo lako skidali s njegove površine zbog čega nisu prošli preliminarna ispitivanja. Kao najbolji ispitani materijali mogu se izdvojiti Z-PCABS, Z-ULTRAT i Z-ABS zbog jasno vidljivih promjena boje filmova na njima, posebice kod upotrebe filma dobivenog kombinacijom prekursora TEOS i FTMS uz dodatak indikatora metil crveno. Iz dobivenih rezultata svih filmova samo dva (oni dobiveni sol-gel postupkom uz prekursore TEOS i FTMS) se mogu uspješno integrirati na ispitane materijale, jer ostali filmovi (NB/PVC, BT i BTG) nisu zadržali senzorska svojstva ili je adhezija između filma i pločica bila preslaba pa su se vrlo lako skidali s istih. Za praktičnu upotrebu u oblaganju kanala mikroreaktora mogao bi se koristiti jedino film s indikatorom metil crveno jer je vrijeme potrebno da dođe do reprezentativnog odziva puno kraće od filma s bromkrezol zelenim.In this work, it is was studied whether the carrier structure (small plates) made of commercial polymer materials, used in additive manufacturing, can be used for the integration of optical chemical sensors in the form of thin films with an immobilized pH indicator. The goal was to gain as much useful informations as possible to develop a thin film that could be used to coat microreactor channels produced by additive manufacturing. A total of eight different polymer materials and glass, which is frequently used as a carrier of this kind of chemical sensors, were used. Five different kinds of thin films and three pH indicators were developed. The first film (NB/PVC) was obtained by dissolving poly(vinyl-chloride) (PVC) in tetrahydrofurane (THF) with addition of lypophilized Nile blue (NB) indicator. The remaining four films were obtained by the sol-gel method, with bromcresol green used in three films and methyl red used in the last film. Sol-gel cocktails were obtained with three different silane precursors (tetraethoxysilane TEOS, glycidoxypropyltrimethoxysilane GLYMO and trimetoxyphenylsilane FTMS) in different ratios were used in interest to investigate the effect of their selection on the properties of obtained thin films. Prepared sol-gel solutions (cocktails) were applied on polymer plates using spin-coating technique. Of all the tested materials, TOUGH (mixture of polyethylene and polypropylene) proved to be the worst choice for this application because all of the examined films were easily removed from its surface, which is why it did not pass preliminary tests. Z-PCABS, Z-ULTRAT and Z-ABS due to clearly visible color changes on the film, especially when using the MTF film obtained by the combination of TEOS and FTMS precursors with the addition of the methyl red indicator, can be distinguished as the best tested materials. From obtained results it was clear that only two films (the ones obtained by sol-gel method with TEOS and FTMS precursors) can be successfully integrated on the tested materials because the other three films (NB / PVC, BT and BTG) did not retain the sensory properties or the adhesion between the film and the plates was so low that they were easily removed from the polymer plates. For the practical use in coating of the microreactor channels, only the film with methyl red could be used because the time necessary for a representative response is shorter then with the bromcresol green