Blends of polyacrylamide—PAM, poly(N-isopropylacrylamide)—PNIPAAm, poly(N-tert-butylacrylamide)—PTBAA, poly(N,N-dimethylacrylamide)—PDMAA and poly(N,N-diethylacrylamide)—PDEAA with poly(ethylene glycol)— PEG were prepared by casting in methanol and water at concentrations of 20 wt%, 40 wt%, 60 wt%, and 80 wt% in PEG. The miscibility of the components was studied by Differential Scanning Calorimetry—DSC. All blend systems are characterized by a single glass transition temperature (T_g), close to the T_g of the amorphous component. The Hoffman Weeks method was used to determine equilibrium melting temperature (T_m) data. The determination of the melt point depression of the blends allowed the calculation of Flory-Huggins interaction parameter (χ₁₂) of the two polymers in the melt, by using the Nishi Wang equation. The interaction parameters, calculated for all the blends, are slightly negative and close to zero, suggesting a partial miscibility between the components.

Summary:In this work, the use of a temperature-sensitive polymer gel, poly(Nisopropylacrylamide), for the concentration of whey proteins was studied. The studied variables were: gel mass/solution volume ratio and concentration temperature. The concentration percentage and the selectivity were determined. The gel 20 Â 5 (20% w/w total monomer/solution and 5% w/w crosslinking agent/total monomer), contacted with whey proteins solutions, at 5 8C and at 20 8C, was capable of concentrating the solution, in protein, from 10 to 33%, depending on the gel mass/solution volume ratio. The separation efficiencies, for the different studied systems, varied from around 40 to 80%. The results were discussed in the context of gels thermodynamics and through correlations between synthesis parameters and structure of the obtained gels. The obtained results for the concentration of whey proteins solutions, by using temperature-sensitive polymer gel, poly(N-isopropylacrylamide), showed that the Gel Process can indeed be used as an advantageous alternative for such separation, either from an economic or from an environmental view point.

In the present work, a methodology of synthesis and characterization of the monomer 2,2 0 diallylbisphenol-A (ABFA) was developed, aiming at getting a precursor, with adequate purity, for obtaining cross-linked membranes based on sulphonated poly(arylene ether sulphone)s. The monomer synthesis involved the synthesis of 2,2 0 bis(4-allyloxiphenyl)propane (Bisphenol-A, diallyl ether -BFAAE), from Bisphenol-A (BFA), followed by Claisen rearrangement of BFAAE, for the production of the target compound 2,2 0 diallylbisphenol-A (ABFA). All the compounds, reagent BFA and obtained products, intermediate product BFAAE and final product ABFA, were characterized by FTIR (Fourier Transform infrared spectroscopy), TGA (Thermo-gravimetric analysis) and HPLC (High-performance liquid chromatography). The compound BFAAE was obtained with a yield of 94.5% and a purity of 97.3%, the latter characterized by TGA and by HPLC. The structure of the product was confirmed by FTIR. The thermal Claisen rearrangement process was conducted by using Differential Scanning Calorimetry (DSC) technique, from a factorial experiment planning, with two factors and three levels, with temperature and time being the variables. The above cited techniques were used for monitoring the Claisen rearrangement and for the characterization of the final product. The best results yield ABFA purity between 85 and 90%, approximately, for 220 8C/60min, 230 8C/30min and 210 8C/90min conditions. The obtained results suggest that, in the studied range, polymerization and degradation of the monomer ABFA occur, simultaneously to its formation.

Poly(arylene ether sulfone)s sulfonated are promising materials for application as proton exchange membranes (PEM) due to their good electrochemical properties. In this study, the synthesis procedure was studied aiming at the production of a new copolymer for use as a PEM. In addition, considering the inefficiency of the recovery route described in the literature, the influence of each monomer in the copolymer recovery from the polymerization solution was evaluated. The monomers were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetry (TG), confirming their structure and purity. The four copolymers, produced as a result of different monomers' molar ratios, were recovered in different ways. While those with sulfonic groups were recovered with acidic solution, the other polymers without pending sulfonic groups were recovered with deionized water. The copolymers were characterized by FTIR, wherein the copolymers characteristic bands were observed, including those characteristic of diaryl ethers, evidence of the proposed polymerization mechanism.