We report on the synthesis of highly transparent and UVabsorbing PMMA/ZnO nanocomposites prepared by hydrolysis of a ZnO precursor, the Ab(AB) diblock copolymer, poly(methyl methacrylate)blockpoly (methyl methacrylateco(zinc methacrylate acetate)), PMMAbP(MMAcoZnMAAc), synthesized by RAFT polymerization. The zinc content of the block copolymers was in the range from 3 to 13 wt %. The PMMA block provides inherent compatibility with the PMMA matrix, whereas the second block, P(MMAcoZnMAAc) with zinc ions, acts as a polymeric precursor for the formation of ZnO nanoparticles. The amphiphilic block copolymer selforganizes in THF and THF/H2O in ordered nanostructures, thereby influencing the nanoparticle formation during the hydrolysis of the precursor block copolymer with KOH in a solvent mixture THF/H2O. The ZnO nanoparticles were rodshaped with lengths up to 80 nm and a diameter of 14 nm and were redispersible in THF. Dispersions in THF and thin films of PMMA/ZnO nanocomposite exhibit excellent transparency in the visible range and good absorption in the UV range below 400 nm. The block copolymer was characterized by SEC, NMR, DLS, and TGA, while PMMA/ZnO nanocomposites were characterized by IR, XRD, UV−vis, and STEM.
COBISS.SI-ID: 5295642
Nanostructured polyanilines (PANI) with various morphology were synthesized by polymerization of aniline with ammonium peroxodisulfate in acidic aqueous medium containing ionic liquids (ILs) with imidazolium, pyridinium and quaternary ammonium cations. The influence of the type of IL and the aniline/IL mole ratio on the morphology and properties of formed PANIs was investigated. ILs added to reaction mixture control the PANI morphology toward nanowires or various complex two and three dimensional structures in contrast to the morphology of agglomerated granular particles that is typical of PANIs prepared in the absence of IL. The UV–Vis, IR and Raman spectra of PANIs showed that the used ILs do not affect the chemical structure of PANI, which indicates that they do not affect the formation of PANI molecules but only their assembling during polymerization. The DLS measurements indicate that ILs as well as their mixtures with an oxidant and aniline form in 1 M HCl ordered micellar structures. The micellar structures most likely act as soft templates that assemble growing PANI chains and/or aniline molecules into particular nanostructures and/or their precursors. The fact that the structure of PANI nanoparticles is, in general, a function of the type of IL and IL/aniline concentration ratio, indicates that the architecture of micelles depends on the same variables.
COBISS.SI-ID: 5194522
The aim of the presented work was to replace phthalate based plasticizers with environmentally friendly materials to provide similar properties for poly(vinyl acetate) adhesives. Polyesters synthesized from the liquefied wood (PE-LW) and depolymerized polyethylene terephthalate (PE-PET) were used as renewable raw materials and evaluated as plasticizers used in PVAc dispersion adhesives for flooring applications. PVAc adhesives were evaluated with respect to solids content, viscosity, glass transition temperature (Tg), tensile shear strength and binding strength. The requirements for the mechanical properties of adhesives were fulfilled by the compositions containing 8.8% (w/w) of PE-PET and 20% (w/w) of PE-LW.
COBISS.SI-ID: 5278234
In this work, the silylation of sodium montmorillonite (MMT, Nanofil 757®) was performed using 3-aminopropyl triethoxy silane (APTES). Different reaction conditions were used varying the reaction time and the amount of the aminosilane. Epoxy-based nanocomposites were prepared with different amounts of silylated MMT or commercial organically modified MMT intercalated with stearylbenzyldimethyl ammonium chloride (Nanofil 2®) and distearyldimethyl ammonium chloride (Nanofil 8®), respectively. The grafting/intercalation of the aminosilane inside the MMT galleries were studied by means of Fourier transform infrared (FTIR), X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and thermogravimetric analysis (TGA). After isothermal curing at 90oC the epoxy-MMT nanocomposites were analyzed by means of XRD and dynamic mechanical analysis (DMA). The glass transition temperature of all prepared composites containing silylated MMT, is slightly higher than that of the neat epoxy (2 to 5 oC). In the presence of 1 to 5 wt % of silylated MMT in epoxy matrix the storage modulus increases of about 5 to 15% at 25o C, respectively, compared to the pristine epoxy matrix, while only 0-4% increase was observed for epoxy nanocomposites with commercial modified MMT.
COBISS.SI-ID: 37176581
The feasibility of incorporating a solid dispersion containing poorly soluble antidiabetic drug glimepiride and poly(ester amide) hyperbranched polymer into a tablet using a direct-compression tabletting technique was investigated.Tablet cores were additionally coated with hydroxypropyl methylcellulose phthalate in order to protect the extremely hygroscopic solid dispersion from atmospheric moisture. Preliminary stability studies show that glimepiride, which is in amorphous form within solid dispersion, is chemically stable, even if tablets are exposed to elevated temperature and/or moisture. In-vitro dissolution studies show some impact of storage conditions on the tablet cores disintegration time and, consequently, drug release rate. Glimepiride solubility also deteriorates somewhat, most probably due to its partial recrystallization. Storage conditions much less affect the physical stability of coated tablets, which was ascribed to reduced tablet hygroscopicity due to the presence of protecting coating. The hyperbranched polymers are rather new and complex macromolecules. Therefore, we addressed also the biocompatibility of hyperbranched polymer, i.e., its impact on haemolysis of the red blood cells. The concentration required for the haemolytic effect on the red blood cells is around 100-times higher than its expected gastrointestinal luminal concentration, which makes the occurrence of hyperbranched polymer mediated cytotoxicity very unlikely.
COBISS.SI-ID: 3075697