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High concentrations of LTA zeolite (27-52mass%) were embedded in poly(methacrylic acid) (PMAA) matrix to obtain composite hydrogels with porosity and active sites originating from both components. Substandard mechanics of PMAA and aggregation of zeolite particles, were thereby overcome. The composites had remarkably higher density than PMAA xerogel (1700 to1400 kg m−3), higher crosslinking density (54.8 to1.29 mol m−3) and lower swelling degree (41 to 420 kg kg−1). Zeolite particles were uniformly dispersed in PMAA matrix and there was no agglomeration or leaching of zeolite despite very high concentrations. XRD patterns revealed that the inclusion of zeolite particles affected the short-range order in the PMAA matrix. Being an active filler LTA zeolite notably improved thermal stability and mechanics of PMAA hydrogel, multiplying the storage modulus 5.2 times in dry and 21.8 times in swollen state. Structure–property correlations were provided making the base for further development of tailor-made zeolite-PMAA composite hydrogels.

The preparation of zeolite rich polymeric materials presents a challenge due to the zeolite settlingduring synthesis, poor miscibility, the phase separation and generally insufficient interactionsbetween polymers and zeolites. Combination of LTA, i.e. MFI, zeolite and poly(methacrylic acid) in theform of soft hydrogel network provided the stabilization of the zeolite particles and enabled synthesisof composite hydrogels with very high zeolite concentrations (26-52 mass%).The investigated morphological, mechanical and primary structural properties, water swelling abilityand thermal stability revealed high dependence on zeolite concentration and type. Zeolite particleswere uniformly dispersed in PMAA matrix as confirmed by SEM and there was no agglomeration orzeolite leaching despite very high concentrations. FTIR spectra disclosed the existence of functionalgroups of PMAA network and both zeolite types that interacted mutually and led to increasedcrosslinking density. The established interactions changed the PMAA chain dynamics around theparticles, especially of the LTA type, as showed by XRD. Having much more surface groups capable togenerate interaction with PMAA, LTA zeolite stronger affected all of the investigated properties.Composites’ mechanics was improved both in dry and swollen state compared to the PMAA hydrogel(up to 21.8 times for the sample with the highest LTA concentration). Thermal stability of thecomposites increased with increasing zeolite concentration.The composition-property correlations were determined making this work the base for furtherdevelopment of tailor-made zeolite-PMAA composite hydrogels aimed for specific application.Composites were tested as low-cost, regenerative, environmentally friendly sorbents and showedbetter removal of cationic dye compared to both components (PMAA and zeolite) alone.

The preparation of zeolite rich polymeric materials presents a challenge due to the zeolite settling during synthesis, poor miscibility, the phase separation and generally insufficient interactions between polymers and zeolites. Combination of LTA, i.e. MFI, zeolite and poly(methacrylic acid) in the form of soft hydrogel network provided the stabilization of the zeolite particles and enabled synthesis of composite hydrogels with very high zeolite concentrations (26-52 mass%). The investigated morphological, mechanical and primary structural properties, water swelling ability and thermal stability revealed high dependence on zeolite concentration and type. Zeolite particles were uniformly dispersed in PMAA matrix as confirmed by SEM and there was no agglomeration or zeolite leaching despite very high concentrations. FTIR spectra disclosed the existence of functional groups of PMAA network and both zeolite types that interacted mutually and led to increased crosslinking density. The established interactions changed the PMAA chain dynamics around the particles, especially of the LTA type, as showed by XRD. Having much more surface groups capable to generate interaction with PMAA, LTA zeolite stronger affected all of the investigated properties. Composites’ mechanics was improved both in dry and swollen state compared to the PMAA hydrogel (up to 21.8 times for the sample with the highest LTA concentration). Thermal stability of the composites increased with increasing zeolite concentration. The composition-property correlations were determined making this work the base for further development of tailor-made zeolite-PMAA composite hydrogels aimed for specific application. Composites were tested as low-cost, regenerative, environmentally friendly sorbents and showed better removal of cationic dye compared to both components (PMAA and zeolite) alone.

Composite hydrogels are the subject of intensive research due to there specific 3D cross-linked structure with extraordinary physical and chemical properties which enables variety of applications In spite of increasing interest for using different external fields in physical-chemical processes, three are no available literature data about the effects of external fields on swelling and swelling kinetics of hydrogels. Therefore, the effects of (conventional) thermal (TH), ultrasonic (US) and microwave (MW) fields, on the swelling degree and swelling kinetics. A sample of poly(methacrylic acid) (PMAA) xerogel with 10%wt of LTA-zeolite (PMMA-LTA) was synthesized and thoroughly characterized. The isothermal kinetic swelling curves were determined within a temperature range T= 293-323K in the TH, US and MW fields. The results were well fitted with the Peppas’ kinetic model. At all applied fields, with an increase in temperature, there is an increase in the equilibrium swelling degree (SDeq) and the swelling rate constant (k), while the parameter of Pepass's model (n) decreases. The maximum value of SDeq and parameter n is achieved at TH, while the US assisted process leads to the maximum value of k. The minimum value of the activation energy (Ea) and at the same time the maximum value of the pre-exponential factor (lnA) lnA were achieved by applying the MW field. The influence of US and MW fields on the diffusion of water molecules through the polymer network, activation of the polymer network for swelling and relaxation of the polymer network was analysed.

High concentrations of hydrophobic MFI zeolite (26.0–51.3 wt%) were successfully embedded in poly(methacrylic acid) (PMAA) network in simple, one-pot synthesis of PMAA-MFI composite hydrogels. The effects of zeolite concentration regarding pure PMAA xerogel, for all of the investigated properties (primary structural parameters, morphological properties, water swelling ability, thermal degradation mechanism and stability, and mechanical properties) were determined and discussed. The PMAA-MFI composite hydrogels had remarkably higher density than PMAA xerogel (1660/1420 kg m−3), higher crosslinking density (29/1.0 × 10−4), improved mechanics in the dry and swollen state (up to 4.9 times higher storage modulus) and lower swelling degree (42/420 g g−1), average molar mass between the network crosslinks (3.6/110 × 104 g mol−1), and distance between the macromolecular chains (64/710 nm). Despite high zeolite concentration, the composites kept porous hydrogel structure with uniformly dispersed zeolite particles. FTIR spectra disclosed the existence of functional groups of PMAA network and MFI zeolite that interacted mutually and led to increased crosslinking density. The effect of zeolite concentration on the thermal degradation mechanism was established. The composition-properties correlations were determined and described by the adequate linear or power law equations revealing the additive nature of the composites and the fractal structure of the networks. These correlations enable the achievement of desired properties by simple adjustment of the initial composition, i.e. zeolite concentration. Therefore, this work presents the base for further development of tailor-made PMAA-MFI composite hydrogels aimed for specific application.

Fluorapatite nanopowders with different amounts of fluoride ions were prepared using the surfactant-assisted microwave method under isothermal conditions. Microwave irradiation was applied for the rapid formation of crystals. A micellar solution of polyoxyethylene (23) lauryl ether was used as a regulator of nucleation and crystal growth. Characterization studies from X-ray diffraction, field-emission scaning electron microscopy and Fourier(-)transform infrared spectra showed that crystals have an apatite structure and particles of all samples are nano size, with an average length of 50 mn and about 15-25 nm in diameter. Antimicrobial studies have demonstrated that synthesized fluorapatite nanopowders exhibit activity against tested pathogens: Eseherichia coli, Staphylococcus aureus and Candida albicans. Activity increased with the amount of fluoride ions. The synthesized fluorapatite nanomaterials are promising as materials in environmental protection and medicine for orthopedics and dental restorations.

The effect of ultraviolet (UV) ozone treatment on the surface properties of gold implanted high density polyethylene (HDPE) was investigated at a nanoscale using Atomic Force Microscopy (AFM). HDPE samples were modified by the implantation of gold ions at a dose of 5 x 10(15) ions/cm(2), using energies of 50, 100, 150, and 200 keV, and subsequently treated with UV/ozone. AFM surface topography images revealed that after UV/ozone treatment, the surface roughness of all Au/HDPE samples increased, while Power Spectral Density function increased only for samples implanted using higher energies, with a maximum for 150 keV. The chemical surface composition was homogenous in all cases, which was evidenced by appearance of single peaks in the histograms obtained from the phase AFM images. For UV/ozone treated samples, the shift of the peaks positions in the histograms to the higher values of the phase lag with respect to untreated ones indicated the decrease of surface hardness. Besides, a significant change of fractal dimension of surface grains is observed after UV/ozone treatment.

The kinetics of the isothermal adsorption of ethanol from an aqueous solution onto a hydrophobic zeolite of the NaZSM-5 type in the temperature range 298-333 K was investigated. Specific shape parameters of the adsorption degree curves were determined. The changes in the specific shape parameters of the adsorption degree curves with temperature were determined. The kinetic parameters of ethanol adsorption (E-a, ln A) were determined by the initial rate, the saturation rate and the maximum rate methods as well as from the Johnson, Mehl and Avramy equation. The kinetic model of ethanol adsorption kt=[1-(1-alpha)(1/3)] was determined by the "model fitting" method. Ethanol adsorption from aqueous solution onto NaZSM-5 is a kinetically controlled process limited by the rate of three-dimensional movement of the boundary layer of the adsorption phase. A model for the mechanism of ethanol adsorption onto NaZSM-5 is suggested on the basis of the kinetic model. Ethanol molecules in aqueous solution are associated in clusters. The activation energy of the adsorption process corresponds to the energy required for the detachment of an ethanol molecule from a cluster and its adsorption onto the zeolite.