Damian Ambrożewicz

An extreme biomimetic approach: hydrothermal synthesis of β-chitin/ZnO nanostructured composites

β-Chitinous scaffolds isolated from the skeleton of marine cephalopod Sepia officinalis were used as a template for the in vitro formation of ZnO under conditions (70 °C) which are extreme for biological materials. Novel β-chitin/ZnO film-like composites were prepared for the first time by hydrothermal synthesis, and were thoroughly characterized using numerous analytical methods including Raman spectroscopy, HR-TEM and XRD. We demonstrate the growth of hexagonal ZnO nanocrystals on the β-chitin substrate. Our chitin/ZnO composites presented in this work show antibacterial properties against Gram positive bacteria and can be employed for development of inorganic-organic wound dressing materials.

Fluoroalkylsilane versus alkylsilane as hydrophobic agents for silica and silicates

Hydrophobic powders were obtained via surface modification of silica or magnesium silicate with selected silanes. A modified precipitation method, carried out in an emulsion system, was used for monodisperse silica synthesis, while magnesium silicate was precipitated in a traditional water system. Functionalization of the obtained inorganic supports was performed with selected alkylsilanes: one newly synthesized, 3-(2,2,3,3,4,4,5,5-octafluoropentyloxy)propyltriethoxysilane (OPF), and two commercial, octadecylsilane (ODS) and octyltriethoxysilane C14H32O3Si (OCS), in amounts of 3, 5, or 10 weight parts by mass of SiO2. It was determined how the chemical modification of the silica or magnesium silicate surface affected its physicochemical properties. The dispersive characteristics of both unmodified and functionalized silica-based systems were evaluated. The morphology and microstructure of the samples obtained were analyzed using scanning electron microscopy. The parameters of porous structure of the prepared systems were evaluated on the basis of BET equation as well as nitrogen adsorption/desorption isotherms. Wettability tests as well as elemental analysis of the obtained inorganic oxide hybrids were also performed. In order to verify the effectiveness of silica and magnesium silicate surface functionalization with selected silanes, FTIR spectra were investigated. The resulting experimental data allowed calculation of the degree of coverage of the silica-based systems with modifying agents.

TiO 2 -SiO 2 /Ph-POSS functional hybrids: preparation and characterisation

The results of studies involving the innovative TiO2-SiO2/Ph-POSS hybrid were presented. An inorganic TiO2-SiO2 oxide composite was precipitated from an emulsion media. The functionalisation of surface for the obtained composite was carried out with the use of Tri Silanol Phenyl POSS (Ph-POSS) and a silane coupling agent--phenyltrimethoxysilane (PTMS). Electrokinetic and physicochemical as well as structural characteristics of obtained hybrids were evaluated. The zeta potential value has been determined, which provides relevant information regarding the interactions between colloid particles. Measurement of the zeta potential values allowed for an indirect assessment of stability for the studied hybrid fillers. In the next step, the degree of dispersion and surface morphology were evaluated based on the obtained particle size distribution curves and TEM images. The hydrophilic hydrophobic character of the surface was assessed by analysing the wettability profiles. The modification degree of the TiO2-SiO2 oxide composite was evaluated based on the infrared spectroscopy studies (FT-IR). Determination of the parameters of the porous structure was conducted by determining the specific surface area and the total volume and mean size of pores. Thermogravimetric measurements (TGA) were also carried out in order to measure the changes in sample mass as a function of temperature.

A novel functional MgO ∙ SiO2/polyhedral oligomeric silsesquioxane hybrids as an active filler of polypropylene

Abstract New organic/inorganic hybrid fillers were obtained by mechanical modification of magnesium silicate with selected polyhedral oligomeric silsesquioxane and characterized afterwards. MgO ∙ SiO2 was precipitated in a water system. The effect of chemical modification of magnesium silicate surface on their physicochemical properties was determined. Functionalization was carried out with the use of different amount of (1-(3-hydroxypropyl)dimethylsiloxy- 3,5,7,9,11,13,15-hepta(isobutyl)pentacyclo-[9.5.1.13, 9.15, 15.17, 13]octasiloxane). The polypropylene composites of 0.5, 1.0 and 1.5 wt.% modified by 10 weight parts by the mass of the filler were also produced. For the obtained polypropylene composites measurements of the tensile strength, Young’s modulus and elongation at break were performed

Thermal properties of polyolefin composites with copper silicate

The aim of this work was to specify thermal properties of polyolefin composites with copper silicate. Low density polyethylene (LDPE) and polypropylene (PP) composites with 2, 4 and 8 wt % of the filler (CuO·SiO2) were analyzed. Characteristic temperatures of the polymer compositions, i.e. the melting (Tm) and crystallization temperatures (Tc), obtained by means of Differential Scanning Calorimetry (DSC), were determined. The impact of the applied additives on composites thermal stability was established using thermogravimetry measurements (TGA). Afterwards, the flammability test was performed. The measurement was complemented with the establishment of the maximum combustion temperature using infrared recording techniques and image analysis (infrared camera). One of the most important parameter of thermoplastics is the softening point which was also determined. The measurement was carried out using a Vicat apparatus. Thermal characteristic was also supplemented with an assessment of the thermal diffusivit...