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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.

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.

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.

The kinetic parameters of the selective isothermal adsorption of ethanol from an aqueous solution onto a hydrophobic zeolite type NaZSM-5 were determined using a series of the so-called standard methods (the initial rate, the saturation rate and the maximum rate methods). The kinetic model of ethanol adsorption was determined by the “model fitting” method. The dependence of the kinetic parameters on the degree of adsorption and the presence of a compensation effect were determined by the isoconversional method. The complex changes of the activation energy and pre-exponential factor with the degree of adsorption were explained by the model of the activation energy distribution of elemental adsorption processes.

The kinetic parameters of the selective isothermal adsorption of ethanol from an aqueous solution onto a hydrophobic zeolite type NaZSM-5 were determined using a series of the so-called standard methods (the initial rate, the saturation rate and the maximum rate methods). The kinetic model of ethanol adsorption was determined by the “model fitting” method. The dependence of the kinetic parameters on the degree of adsorption and the presence of a compensation effect were determined by the isoconversional method. The complex changes of the activation energy and pre-exponential factor with the degree of adsorption were explained by the model of the activation energy distribution of elemental adsorption processes.

Thermogravimetric (TG) and differential thermogravimetric analyses (DTG) of some homo- and copolymers of dimethylsiloxane have been performed. The effect of the presence of hydrido-substituents and/or vinyl end-groups on the thermal and thermo-oxidative stability of the examined polysiloxanes was determined. In all cases it was found that these polysiloxanes are thermally less stable than the parent all-methyl polysiloxane.

A new general procedure for preparation of functionalized oligopolysiloxanes of predetermined molecular weight is described. It utilizes heterogeneously catalyzed siloxane equilibration polymerization reactions which do not require troublesome and sometimes difficult post-preparative work-up procedures usually encountered with the well known homogeneously catalyzed corresponding reactions. The method is described using as example the preparation of α, ω-telechelic vinyldimethylsiloxy-oligopolydimethylsiloxanes from octamethylcyclotetrasiloxane and 1,3-divinyltetramethyldisiloxane, but reference to the preparations of trimethylsiloxy-, dimethylsiloxy-and carboxypropyldimethylsiloxyoligopolydimethylsiloxanes, oligopolymethylhydridosiloxanes or their copolymers is also made.