Removal of textile dyes and metallic ions using polyelectrolytes and macroelectrolytes containing sulfonic acid groups.

This work reports the removal of textile dyes and metallic ions by means of adsorption and coagulation-flocculation using two polyelectrolytes and two macroelectrolytes containing sulfonic acid groups. The adsorption of textile dyes was studied in aqueous solutions containing cationic dyes and in wastewater containing a vat dye. Also, removal of vat and naphthol dyes was studied using the process of coagulation-flocculation. The results show these materials possess elevated adsorption capacity, and they accomplished removal rates above 97% in aqueous solutions. The removal of the vat dye improved the quality of the wastewater notably, and an uncolored effluent was obtained at the end of the treatment. The treatment using adsorption decreased the values for coloration, conductivity, suspended solids, and pH. The removal of vat and naphthol dyes by means of coagulation-flocculation was studied as well, and removal rates of 90% were obtained. The polyelectrolytes and macroelectrolytes also proved effective in the adsorption of metallic ions in wastewater. The treatment using adsorption accomplished high removal rates of metallic ions, and it showed greater selectivity towards Cu(2+), Fe(3+) and Pb(2+). A decrease in the content of solids as well as the values for COD and conductivity was observed in the wastewater as well. The analyses of FT-IR indicated that cationic dyes and metallic ions were chemisorbed by means of ionic exchange.

Evaluation of a biobased polycarbonate interpenetrated network in a dental resin composite.

Silanization of filler particles in a dental resin composite is achieved by the formation of Si-O-Si bonds, however, these bonds are especially vulnerable to hydrolysis because this covalent bond has a significant ionic character due to the electronegativity differences between the atoms. The objective of this study was to evaluate the use of an interpenetrated network (IPN) as alternative of silanization reaction and to assess its effect in selected properties of experimental photopolymerizable resin composites. The interpenetrate network was obtained during the photopolymerization reaction of organic matrix (BisGMA/TEGDMA) with a biobased polycarbonate. Its characterization was performed via FTIR, flexural strength, flexural modulus, depth of cure, sorption water and solubility. A resin composite formulated with non-silanized filler particles was used as control. The IPN with a biobased polycarbonate was successfully synthesized. The results showed that the IPN based resin composite had higher values of flexural strength, flexural modulus, and degree of double bond conversion than the control (p < 0.05). Polymerization shrinkage, water sorption and solubility were statistically significantly lower than the control resin (p < 0.05). Finally, this study shows there were no statistically significant differences for the biocompatibility outcomes (p > 0.05). The biobased IPN replaces the silanization reaction in resin composites, improving physical and chemical properties. Therefore, IPN with a biobased polycarbonate could be potentially useful in the formulation of dental resin composites.

Adhesive Resins with High Shelf-Life Stability Based on Tetra Unsaturated Monomers with Tertiary Amines Moieties.

This work reports the use of two monomers with two tertiary amines and four methacrylic (TTME) or acrylic (TTAC) terminal groups as co-initiators in the formulation of experimental resin adhesive systems. Both monomers were characterized by FT-IR and 1H NMR spectroscopies. The control adhesive was formulated with BisGMA, TEGDMA, HEMA, and the binary system CQ-EDAB as a photo-initiator system. For the experimental adhesives, the EDAB was completely replaced for the TTME or the TTAC monomers. The adhesives formulated with TTME or TTAC monomers achieved double bond conversion values close to 75%. Regarding the polymerization rate, materials formulated with TTME or TTAC achieved lower values than the material formulated with EDAB, giving them high shelf-life stability. The degree of conversion after shelf simulation was only reduced for the EDAB material. Ultimate tensile strength, translucency parameter, and micro-tensile bond strength to dentin were similar for control and experimental adhesive resins. Due to their characteristics, TTME and TTAC monomers are potentially useful in the formulation of photopolymerizable resins for dental use with high shelf-life stability.

Dental composite resins with low polymerization stress based on a new allyl carbonate monomer.

The objective of this study was to synthesize a diallyl carbonate monomer, allyl(2-(2-(((allyloxy)carbonyl)oxy)benzoyl)-5-methoxyphenyl) carbonate (BZ-AL), and to evaluate its effect as Bis-GMA diluent in the formulation of photopolymerizable dental composite resins. The chemical structure of BZ-AL monomer was determined by means of H1 NMR, C13 NMR and FTIR spectroscopies. An experimental composite comprising a mixture of Bis-GMA and BZ-AL monomers and silanized inorganic filler was formulated. Experimental material was compared with a control composite formulated with Bis-GMA/TEGDMA. Double bond conversion, polymerization kinetics, volumetric shrinkage, polymerization stress, and flexural properties were investigated. The data were analyzed through a Student t-test (α = 0.05). Flexural strength of the experimental materials with BZ-AL monomer showed a statistically significant increase (p < 0.001). The experimental composite has a lower polymerization rate than the control composite, on the other hand, the experimental composite resin has the highest degree of double bond conversion. There are no differences in the polymerization shrinkage of the composites, however, the polymerization stress of the experimental materials was 50% lower than the control resin. Finally, the cell viability test showed that the experimental resins formulated with the BZ-AL monomer was not cytotoxic. Due to its characteristics, BZ-AL monomer is potentially useful for the formulation of composite materials with applications in dentistry.

Evaluation of dental composites resins formulated with non-toxic monomers derived from catechol.

Two liquid monomers (CT-AL and CT-ACR) were synthesized from the acylation of tert-butyl catechol with different acid chlorides. The monomers were used to prepare photopolymerizable dental composite for completely replacing TEGDMA. Properties such as flexural strength, modulus of elasticity, degree of double bond conversion, polymerization shrinkage, as well as the polymerization stress were studied. Also, color alteration, translucency, and cytotoxicity were evaluated. The results show that the experimental materials formulated with CT-AL and CT-ACR have similar mechanical properties to a control material formulated with BisGMA/TEGDMA, similar polymerization shrinkage, and less polymerization stress. The composite formulated with the CT-AL monomer shows a similar degree of conversion (72%), while the composite formulated with the CT-ACR monomer has a degree of conversion lower (58%) than the control resin (71%). These results suggest that both monomers could have potential applications in the formulation of composites for dental restorations.

Preparation and evaluation of a BisGMA-free dental composite resin based on a novel trimethacrylate monomer.

OBJECTIVE: The use of the BisGMA as base monomer in dental composites has been questioned because of bisphenol A (BPA) is used as raw material in its synthesis, and BPA possess estrogenic potential associated to several health problems. This study describes the synthesis of the trimethacrylate tris(4-hydroxyphenyl)methane triglycidyl methacrylate (TTM) monomer and evaluate its effect when used as base monomer in the formulation of experimental photopolymerizable composite resins. METHODS: The TTM monomer was synthesized by a nucleophilic acyl substitution. Its chemical structure was confirmed via 1H and 13C NMR spectroscopy and FTIR spectroscopy. Experimental composite resins were formulated by mixing TTM, triethyleneglycol dimethacrylate (TEGDMA) and inorganic fillers. A BisGMA/TEGDMA based composite resin was prepared and used as control to compare several physicochemical properties. Cell viability assay was used for cytotoxicity evaluation. RESULTS: TTM was successfully synthesized with quantitative yields. The results showed that the TTM-based composite resin had similar values of flexural strength, elastic modulus, degree of conversion and polymerization shrinkage than the control (p > 0.05). Water sorption and solubility were statistically significantly higher than the control (p < 0.05), however they complied the requirements stablished by the ISO 4049. Finally, this study shows there were no statistically significant differences for the biocompatibility outcomes (p = 0.345). SIGNIFICANCE: TTM monomer could be potentially useful in the formulation of BisGMA free composite resins, which could mean to minimize the human exposure to BPA.

Synthesis of an allyl carbonate monomer as alternative to TEGDMA in the formulation of dental composite resins.

Over the past years, significant effort has been dedicated to synthesizing low-shrinking formulations, however, development of dental composites with low volumetric shrinkage continues to be challenging. The purpose of this study was to synthesize a bisphenol allylic derivate (BPhADAC) and evaluate its inclusion in the formulation of a photopolymerizable dental composite resin, as a BisGMA diluent. Experimental (BisGMA/BPhADAC) and control (BisGMA/TEGDMA) photopolymerizable composites were prepared. Double bond conversion, polymerization kinetics, volumetric shrinkage, water sorption, solubility, and flexural properties were investigated. The experimental composite showed higher degree of conversion values, less volumetric shrinkage and less water sorption than the control composite (p < 0.05). In addition, flexural strength between the materials was found to be similar. The overall properties prove that the allylic monomer BPhADAC could be potentially useful in the formulation of low-shrinking dental composite resins.

Fluorescent polyacrylate derivate from 4-biphenylmethanol with UV-green emission.

In this paper we report the synthesis of a new polyacrylate named poly(1,1'-BP4MA) which is a derivate from 4-biphenylmethanol monomer. Poly(1,1'-BP4MA) was obtained by solution and bulk polymerization techniques to yield polymers with high molecular weight and high solubility. The study of the optical properties showed that poly(1,1'-BP4MA) is a fluorescent material with emission in the UV-green region and it has similar quantum yield to tryptophan.

Evaluation of biocompatible monomers as substitutes for TEGDMA in resin-based dental composites.

This works reports the synthesis and characterization of diallyl(5-(hydroxymethyl)-1,3-phenylene) dicarbonate (HMFBA) and 5-(hydroxymethyl)-1,3-phenylene bis(2-methylacrylate) (HMFBM) monomers and its evaluation as Bis-GMA eluents in the formulation of composite resins for dental use. The experimental materials formulated with HMFBA and HMFBM monomers presented flexural strength values similar to those of the control group formulated with Bis-GMA/TEGDMA. Regarding volumetric contraction percentage, the values obtained of experimental materials with HMFBA was 1.88% and for HMFBM was 4.15%, both lower than control resin (4.68%). In the case of double bond conversion, the resin formulated with HMFBA monomer exhibited a greater degree of conversion (87%). Besides, the DMA analyses proved that the values for Tg guarantee a good mechanical performance at body temperature. The new resins formulated with HMFBA and HMFBM monomers exhibit a cellular viability close to 100%, which indicates the absence of cytotoxicity towards fibroblastic cells.