New Insights into the Application of Biocompatible (Un)Modified TiO2 and TiO2-ZrO2 Oxide Fillers in Light-Curing Materials.

A novel UV-light-curable poly(ethylene glycol) diacrylate matrix composite material with unmodified and methacryloxyl-grafted TiO2 and TiO2-ZrO2 systems was developed and tested as a potential coating material for medical components. The main goal of the research was to evaluate how the addition of (un)modified inorganic oxide fillers affects the properties of the composition (viscosity, UV/Vis spectra), the kinetics of photocuring (photo-DSC), and the morphological (SEM), physicochemical, and thermal properties (DSC, TGA) of the resulting composites. The applied filler functionalization process decreased their polarity and changed their size, BET surface area, and pore volume, which influenced the viscosity and kinetics of the photocurable system. In addition, the addition of synthesized fillers reduced the polymer's glass transition temperature and increased its thermal stability. It was also observed that additional UV irradiation of the tested composite changed its surface, resulting in hydrophobic properties (with the addition of 7 wt.% filler, an increase in the contact angle by more than 45% was observed).

Surface-Active Ionic Liquids and Surface-Active Quaternary Ammonium Salts from Synthesis, Characterization to Antimicrobial Properties.

The present work provides new evidence of the ongoing potential of surface-active ionic liquids (SAILs) and surface-active quaternary ammonium salts (surface-active QASs). To achieve this, a series of compounds were synthesized with a yield of ≥85%, and their thermal analyses were studied. Additionally, antimicrobial activity against both human pathogenic and soil microorganisms was investigated. Subsequently, their surface properties were explored with the aim of utilizing SAILs and surface-active QASs as alternatives to commercial amphiphilic compounds. Finally, we analyzed the wettability of the leaves' surface of plants occurring in agricultural fields at different temperatures (from 5 to 25 °C) and the model plant membrane of leaves. Our results show that the synthesized compounds exhibit higher activity than their commercial analogues such as, i.e., didecyldimethylammonium chloride (DDAC) and dodecyltrimethylammonium bromide (C12TAB), for which the CMC values are 2 mM and 15 mM. The effectiveness of the antimicrobial properties of synthesized compounds relies on their hydrophobic nature accompanied by a cut-off effect. Moreover, the best wettability of the leaves' surface was observed at 25 °C. Our research has yielded valuable insights into the potential effectiveness of SAILs and surface-active QASs as versatile compounds, offering a promising alternative to established antimicrobials and crop protection agents, all the while preserving substantial surface activity.

Hydrogel Polymer Electrolytes: Synthesis, Physicochemical Characterization and Application in Electrochemical Capacitors.

Electrochemical capacitors operating in an aqueous electrolyte solution have become ever-more popular in recent years, mainly because they are cheap and ecofriendly. Additionally, aqueous electrolytes have a higher ionic conductivity than organic electrolytes and ionic liquids. These materials can exist in the form of a liquid or a solid (hydrogel). The latter form is a very promising alternative to liquid electrolytes because it is solid, which prevents electrolyte leakage. In our work, hydrogel polymer electrolytes (HPEs) were obtained via photopolymerization of a mixture of acrylic oligomer Exothane 108 with methacrylic acid (MAA) in ethanol, which was later replaced by electrolytes (1 M Na2SO4). Through the conducted research, the effects of the monomers ratio and the organic solvent concentration (ethanol) on the mechanical properties (tensile test), electrolyte sorption, and ionic conductivity were examined. Finally, hydrogel polymer electrolytes with high ionic conductivity (σ = 26.5 mS∙cm-1) and sufficient mechanical stability (σmax = 0.25 MPa, εmax = 20%) were tested using an AC/AC electrochemical double layer capacitor (EDLC). The electrochemical properties of the devices were investigated via cyclic voltammetry, galvanostatic charge/discharge, and impedance spectroscopy. The obtained results show the application potential of the obtained HPE in EDLC.

The Use of Hot Melt Extrusion to Prepare a Solid Dispersion of Ibuprofen in a Polymer Matrix.

In this work, we report the use of the hot melt extrusion method in harsh extrusion conditions, i.e., screw rotation speed of 250 rpm, temperature above 100 °C, and two mixing zones, in order to obtain an amorphous dispersion of an active pharmaceutical ingredient (API) that is sparingly soluble in water. As a polymer matrix Eudragit EPO (E-EPO) and as an API ibuprofen (IBU) were used in the research. In addition, the plasticizer Compritol 888 ATO (COM) was tested as a factor potentially improving processing parameters and modifying the IBU release profile. In studies, 25% by weight of IBU, 10% of COM and various extrusion temperatures, i.e., 90, 100, 120, 130, and 140 °C, were used. Hot melt extrusion (HME) temperatures were selected based on the glass transition temperature of the polymer matrix (Tg = 42 °C) and the melting points of IBU (Tm = 76 °C) and COM (Tm = 73 °C), which were tested by differential scanning calorimetry (DSC). The thermal stability of the tested compounds, determined on the basis of measurements carried out by thermogravimetric analysis (TGA), was also taken into account. HME resulted in amorphous E-EPO/IBU solid dispersions and solid dispersions containing a partially crystalline plasticizer in the case of E-EPO/IBU/COM extrudates. Interactions between the components of the extrudate were also studied using infrared spectroscopy (FTIR-ATR). The occurrence of such interactions in the studied system, which improve the stability of the obtained solid polymer dispersions, was confirmed. On the basis of DSC thermograms and XRPD diffractograms, it was found that amorphous solid dispersions were obtained. In addition, their stability was confirmed in accelerated conditions (40 °C, 75% RH) for 28 days and 3 months. The release profiles of prepared tablets showed the release of 40% to 63% of IBU from the tablets within 180 min in artificial gastric juice solution, with the best results obtained for tablets with E-EPO/IBU extrudate prepared at a processing temperature of 140 °C.

Synthesis and Surface Properties of Piperidinium-Based Herbicidal Ionic Liquids as a Potential Tool for Weed Control.

A series of piperidinium-based herbicidal ionic liquids (HILs) were synthesized and investigated. The designed HILs, obtained with high yields, consisted of cation 1-alkyl-1-methylpiperidinium with surface activity and a commercially available herbicidal anion: (3,6-dichloro-2-methoxy)benzoates (dicamba). The above-mentioned compounds were characterized in terms of surface activity and phytotoxicity. Preliminary results were obtained at higher wettability for all HILs when compared to the wettability of commercial Dicash, with HIL having 18 atoms in the carbon chain being the best effectiveness in wetting surfaces (weeds and crop leaves), whereby a drop of HILs with short alkyl chains (C8-C10) could not slide down a leaf. Our findings present that wettability or mobility of HILs drops varied depending on the plant species. Moreover, in this study, by zeta potential and atomic force microscopy measurements, we provide conclusive evidence to demonstrate that alkyl chain elongation plays a significant role in the evolution of surface properties of HILs.

Influence of Initiator Concentration on the Polymerization Course of Methacrylate Bone Cement.

Background: The amount of oxidant (initiator) and reductant (co-initiator) and their ratio have a significant effect on the properties of polymethacrylate bone cement, such as maximum temperature (Tmax), setting time (tset) and compressive strength (σ). The increase in the initiating system concentration causes an increase in the number of generated radicals and a faster polymerization rate, which shortens the setting time. The influence of the redox-initiating composition on the course of polymerization (rate of polymerization and degree of double bond conversion) and the mechanical properties of bone cement will be analyzed. Methods: Bone cements were synthesized by mixing a powder phase composed of two commercially available methacrylate copolymers (Evonic) and a liquid phase containing 2-hydroxyethyl methacrylate (HEMA), methyl methacrylate (MMA), and triethylene glycol dimethacrylate (D3). As an initiating system, the benzoyl peroxide (BPO) as an oxidant (initiator) in combination with a reducing agent (co-initiator), N,N-dimethylaniline (DMA), was used. Samples were prepared with various amounts of peroxide BPO (0.05%, 0.1%, 0.2%, 0.3%, 0.5% and 0.7% by weight) with a constant amount of reducing agent DMA (0.5 wt.%), and various amounts of DMA (0.25%, 0.35% and 0.5% by weight) with a constant amount of BPO (0.3 wt.%). The polymerization kinetics were studied by differential scanning calorimetry (DSC). Doughing time and compressive strength tests were carried out according to the requirements of the ISO 5833:2002 standard. Results: The increase in polymerization rate was due to the increase in the amount of BPO. In addition, the curing time was shortened, as well as the time needed to achieve the maximum polymerization rate. The final conversion of the double bonds in the studied compositions was in the range 74-100%, and the highest value of this parameter was obtained by the system with 0.3 wt.% of BPO. The doughing times for each BPO concentration were in the range of 90-140 s. The best mechanical properties were obtained for the cement following the initiating system concentrations: 0.3 wt.% of BPO and 0.5 wt.% of DMA. Nevertheless, all tested cements met the requirements of the ISO 5833:2002 standard. Conclusions: Based on the conducted polymerization kinetic studies, the best reaction conditions are provided by an initiating system containing 0.3 wt.% of BPO oxidant (initiator) and 0.5 wt.% of DMA reductant (co-initiator). A decrease in the DMA amount caused a decrease in the polymerization rate and the amount of heat released during the reaction. The change in BPO and DMA concentrations in the composition had little effect on the doughing time of the studied bone cement. The cements showed similar doughing times, ranging from 90-225 s, which is comparable to the bone cement available on the market.

Gel Polymer Electrolytes with Mixture of Triazolium Ionic Liquids and Propylene Carbonate.

This study is focused on the structural influence of 1,2,4-triazolium ionic liquid (IL), that is, the effect of the length of the substituent and the type of substitution (1-methyl-4-alkyl or 1-alkyl-4-methyl) used in the mixture with propylene carbonate (PC) on the properties of thiol-ene polymer ionogels and on the preparation of an ionogel with satisfactory mechanical and conductive properties. PC allows for higher conductivity but also causes electrolyte leakage from the gel. When using triazolium IL (instead of the imidazolium one), because of the stronger interactions between components of the system, the ionogels do not leak. In this study, 1,4-dialkyl-1,2,4-triazolium ILs were successfully synthesized by the alkylation of 1,2,4-triazole. Subsequently, gel polymer electrolytes were obtained by one-pot thiol-ene photopolymerization reactions of tetrafunctional thiols with different chemical structures: pentaerythritol tetra(3-mercaptopropionate) (PETMP) or pentaerythritol tetra(3-mercaptobutyrate) (PETMB) and trifunctional ene (TATT) in the presence of a mixture of 1,4-dialkyl-1,2,4-triazolium IL with PC. Measurements made by electrochemical impedance spectroscopy showed that all ionogels with TATT+PETMB as a polymer matrix presented smaller relative ionic conductivity compared to ionogels containing TATT+PETMP. The puncture resistance and elongation at puncture, measured by the puncture resistance method, were higher for ionogels with poly(TATT+PETMB) than for those with poly(TATT+PETMP). Moreover, ILs containing a methyl group in position N1 of the 1,2,4-triazole ring presented lower puncture resistance than ionogels with ILs containing a methyl group in position N4, especially for shorter alkyl chains. Additionally, the photo-differential scanning calorimetry method was employed to characterize the course of photopolymerization. The compositions and their constituents were characterized by UV and IR spectroscopy.

Design, Fabrication and Analysis of Magnetorheological Soft Gripper.

The magnetorheological elastomer is promising material for applications in soft robotics. Its properties like reactive to external magnetic field and softness allow to construct an attractive devices. This work presents a construction of soft gripper assembled with magnetorheological elastomers. The work describes the detailed molding process of magnetorheological elastomers. Further, the electromechanical properties of magnetorheological elastomers are shown using a simple beam. Finally, the soft gripper is constructed and analyzed with the series of experiments.

Poly(vinylbenzyl Pyridinium Salts) as Novel Sorbents for Hazardous Metals Ions Removal.

Novel efficient complexing resins-poly(vinylbenzyl pyridinium salts) fabricated through poly(vinylbenzyl halogene-co-divinylbenzene) quaternization of N-decyloxy-1-(pyridin-3-yl)ethaneimine and N-decyloxy-1-(pyridin-4-yl)ethaneimine-were tested as adsorbents of Pb(II), Cd(II), Cu(II), Zn(II), and Ni(II) from aqueous solutions. The structure of these materials was established by 13C CP-MAS NMR, X-ray photoelectron spectroscopy, elemental analysis, and Fourier transform infrared spectroscopy, as well as thermogravimetric and differential thermal analyses. The textural properties were determined using scanning electron microscopy and low-temperature N2 sorption. Based on the conducted sorption studies, it was shown that the uptake behavior of the metal ions towards novel resins depended on the type of functionalities, contact time, pH, metal concentrations, and the resin dosage. The Langmuir model was investigated to be the best one for fitting isothermal adsorption equilibrium data, and the corresponding adsorption capacities were predicted to be 296.4, 201.8, 83.8, 38.1, and 39.3 mg/g for Pb(II), Zn(II), Cd(II), Cu(II), and Ni(II), respectively. These results confirmed that owing to the presence of the functional pyridinium groups, the resins demonstrated proficient metal ion removal capacities. Furthermore, VBBr-D4EI could be successfully used for the selective uptake of Pb(II) from wastewater. It was also shown that the novel resins can be regenerated without significant loss of their sorption capacity.

The Influence of Monomer Structure on the Properties of Ionogels Obtained by Thiol-Ene Photopolymerization.

The influence of ene and thiol monomer structure on the mechanical and electrochemical properties of thiol-ene polymeric ionogels were investigated. Ionogels were obtained in situ by thiol-ene photopolymerization of 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TATT), 2,4,6-triallyloxy-1,3,5-triazine (TAT), diallyl phthalate (DAP), and glyoxal bis(diallyl acetal) (GBDA) used as enes and trimethylolpropane tris(3-mercaptopropionate) (TMPTP), pentaerythritol tetrakis(3-mercaptopropionate) (PETMP), and pentaerythritol tetrakis(3-mercaptobutyrate) (PETMB) used as thiols in 70 wt.% of ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMImNTf2). The mechanical strength of ionogels was studied by puncture resistance and ionic conductivity by electrochemical impedance spectroscopy. The course of photopolymerization by photo-DSC method (differential scanning calorimetry) as well as characterization of compositions and its components (by IR and UV spectroscopy-Kamlet-Taft parameters) were also studied. The resulting ionogels were opaque, with phase separation, which resulted from the dispersion mechanism of polymerization. The mechanical and conductive properties of the obtained materials were found to be largely dependent on the monomer structure. Ionogels based on triazine monomers TAT and TATT were characterized by higher mechanical strength, while those based on aliphatic GBDA had the highest conductivity. These parameters are strongly related to the structure of the polymer matrix, which is in the form of connected spheres. The conductivity of ionogels was high, in the range of 3.5-5.1 mS∙cm-1.

Optimization of the Properties of Photocured Hydrogels for Use in Electrochemical Capacitors.

In this work, hydrogel polymer electrolytes (HPEs) were obtained by the photopolymerization of a mixture of two monomers: Exothane 8 (Ex8) and 2-hydroxyethylmethacrylate acid phosphate (HEMA-P) in an organic solvent N-methyl-2-pyrrolidone (NMP), which was replaced after polymerization with water, and then with the electrolyte. The ratio of monomers as well as the concentration of NMP was changed in the composition to study its influence on the properties of the HPE: conductivity (electrochemical impedance spectroscopy, EIS) and mechanical properties (puncture resistance). Properties were optimized using a mathematical model to obtain a hydrogel with both good mechanical and conductive properties. To the best of our knowledge, it is the first publication that demonstrates the application of optimization methods for the preparation of HPE. Then, the hydrogel with optimal properties was tested as a separator in a two-electrode symmetric AC/AC pouch-cell. The cells were investigated by cyclic voltammetry galvanostatic charge/discharge with potential limitation and EIS. Good mechanical properties of HPE allowed for obtaining samples of smaller thickness while maintaining very good dimensional stability. Thus, the electrochemical capacitor (EC) resistance was reduced and their electrochemical properties improved. Moreover, photopolymerization kinetics in the solvent and in bulk by photo-DSC (differential scanning calorimetry) were performed. The great impact on the polymerization of HEMA-P and its mixtures (with Ex8 and NMP) have strong intermolecular interactions between reagents molecules (i.e., hydrogen bonds).

Novel Polymer Sorbents with Imprinted Task-Specific Ionic Liquids for Metal Removal.

In this paper, the potential of novel polymer sorbents with the imprinted IL-functional group for the removal of Cu(II), Cd(II), and Zn(II) from aqueous solutions was investigated by batch mode. The sorbents were fabricated by direct reaction of the prepared polymer matrix (poly(vinylbenzyl chloride-divinylbenzene), VBC, and poly(vinylbenzyl bromide-divinylbenzene), VBBr) with 1-(3- or 4-pyridyl)undecan-1-one and oxime of 1-(3- or 4-pyridyl)undecan-1-one. The Fourier Transform Infrared Spectroscopy (FT-IR), Raman Spectroscopy (Raman), Thermogravimetric Analysis (TG), Differential Scanning Calorimetry (DSC), and Scanning Electron Microscopy (SEM) techniques were used to show functionality and stability of the sorbents. The materials were also characterized by contact-angle goniometry, X-rayphotoelectron spectroscopy (XPS), and Zeta potential analysis. The removal of Cd(II), Cu(II), and Zn(II) was monitored and optimized under the influence of several operational controlling conditions and factors such as pH, shaking time, temperature, initial metal ions concentration, and counter-ions at the functional group. The results obtained confirmed the very high potential of the sorbents; however, the properties depend on the structure of the functional group. The tested sorbents showed fast kinetics, significant capacity at 25 °C (84 mg/g for the Zn(II) sorption with VBC-Ox4.10, 63 mg/g for the Cd(II) sorption with VBBr-Ox3.10, and 69 mg/g for the Cu(II) sorption with VBC-K3.10), and temperature dependence (even 100% increase in capacity values at 45 °C). The selected sorbent can be regenerated without a significant decrease in the metal removal efficiency.

Ionogels Obtained by Thiol-ene Photopolymerization-Physicochemical Characterization and Application in Electrochemical Capacitors.

Flexible ionogels with good mechanical properties were obtained in situ by thiol-ene photopolymerization of trimethylolpropane tris(3-mercaptopropionate) (TMPTP) and 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TATT) (with C=C: SH ratio 1:1) in four imidazolium ionic liquids (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide-EMImNTf2, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate-EMImOTf, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide-BMImNTf2, and 1-butyl-3-methylimidazolium trifluoromethanesulfonate-BMImOTf) used in the range 50 to 70 wt.%. The mechanical and electrochemical properties of obtained ionogels were examined. Ionogels with ionic liquids (ILs) with NTf2- anion are more puncture resistant than with OTf⁻ anion. Moreover, ionogels with the NTF2- anion have better electrochemical properties than those with the OTf⁻ anion. Although it should be noted that ionogels with the EMIm+ cation have a higher conductivity than the BMIm+. This is connected with intermolecular interactions between polymer matrix and IL related to the polarity of IL described by the Kamlet-Taft parameters. These parameters influence the morphology of the polymer matrix (as shown by the SEM micrograph), which is formed by interconnected polymer spheres.

Modification of Thiol-Ene Ionogels with Octakis(methacryloxypropyl) Silsesquioxane.

The effect of polyhedral oligomeric silsesquioxane (POSS) on the synthesis and properties of hybrid organic-inorganic ionogels was investigated using octakis(methacryloxypropyl) silsesquioxane (methacryl-POSS). Ionogels were prepared in situ by thiol-ene photopolymerization of triallyl isocyanurate with pentaerythritol tetrakis(3-mercaptopropionate) in a mixture of imidazolium ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMImNTf2) and propylene carbonate (PC). Investigations included the kinetics of hybrid materials formation and selected physical and mechanical properties. The disadvantage of ionogels without the methacryl-POSS modifier is leakage and insufficient mechanical properties. Modifying the thiol-ene matrix by the addition of methacryl-POSS made it possible to obtain non-leaking ionogels with improved mechanical and conductive properties. The steric hindrance of POSS cages and high-density network formation played important roles in ionogel synthesis: decrease of polymerization rate (with almost no effect on conversion), as well as dimensions of the formed polymer spheres during dispersion polymerization (highly cross-linked polymer has poorer solubility in polymerizing medium at a similar conversion, and nucleation begins at lower conversion), an increase of glass transition temperature and puncture strength. Hybrid ionogels with high ionic conductivity in the range of 4.0-5.1 mS∙cm-1 with the maximum parameter for 1.5 wt.% addition of the methacryl-POSS were obtained, which can be associated with ion-pair dissociations in ionic liquid clusters caused by methacryl-POSS.

Anchor Effect in Polymerization Kinetics: Case of Monofunctionalized POSS.

The effect of the anchoring group on the detailed polymerization kinetics was investigated using monomethacryloxy-heptaisobutyl POSS (1M-POSS). This compound was copolymerized with lauryl methacrylate (LM) as the base monomer, at various molar ratios. The process was initiated photochemically. The polymerization kinetics were followed by photo-DSC and photorheology while the polymers were characterized by nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). For comparison, a methacrylate containing the branched siloxy-silane group (TSM) was also studied. It was found that the modifiers with a bulky substituent have a dual effect on the termination process: (i) At low concentrations, they increase the molecular mobility by increasing the free volume fraction, which leads to an acceleration of the termination and slows the polymerization; while (ii) at higher concentrations, they retard molecular motions due to the "anchor effect" that suppresses the termination, leading to acceleration of the polymerization. The anchor effect can also be considered from a different point of view: The possibility of anchoring a monomer with a long substituent (LM) around the POSS cage, which can further enhance propagation. These conclusions were derived based on kinetic results, determination of polymerization rate coefficients, and copolymer analysis.

The electrical properties and glass transition of some dental materials after temperature exposure.

The physicochemical properties of dental materials will remain stable only when these materials in question are resistant to the changes in the oral cavity. The oral environment is subject to large temperature variations. The aim of the study was the assessment of electrical properties and glass transition of some dental materials after temperature exposure. Composite materials, compomers, materials for temporary prosthetic replacement and resin-based pit and fissure sealants were used in the study. The method used was electric conductivity of materials under changing temperature. The order of materials presenting the best characteristics for insulators was as follows: materials for temporary prosthetic replacement, resin-based pit and fissure sealants, composites, and compomers. Thanks to comparisons made between graphs during I and II heating run, the method could be used to observe changes in the heated material and determine whether the changes observed are reversible or permanent. The graphs also provided temperature values which contain information on glass transition during heating. In the oral cavity the effect of the constant temperature stimulus influences maturity of dental materials and improves their properties. But high temperatures over glass transition temperature can cause irreversible deformation and changes of the materials properties, even in a short time.