The frontal ring opening metathesis polymerization of dicyclopentadiene using first and second generation Grubbs' catalysts is reported. To have sufficiently long pot lives, dimethylaminopyridine is added as an inhibitor. By choosing the proper compositions, it is possible to determine the ranges in which pure frontal polymerization occurs. A thorough study on the effect of the above components on the maximum temperatures reached by the front and on its velocities is performed. Namely, temperatures range from 164 to 205 °C depending on the type of catalyst and the above component ratios. Besides, front velocities range from 1.0 to 15.0 cm/min, which are one of the lowest and one of the highest values reported so far in any frontal polymerization experiment reported in literature. This finding allows the complete control of the frontal ring opening polymerization of dicyclopentadiene also in practical applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2776–2780

Functionally gradient materials (FGMs) with gradual and continuous changes of their properties in one or more dimensions are useful in a wide range of applications. However, obtaining such materials with accurate control of the gradient, especially when the gradient is nonlinear, is not easy. In this work, frontal polymerization (FP) was exploited to synthesize polymeric FGMs. We demonstrated that the use of ascending FP with continuous feeding of monomers with computer-controlled peristaltic pumps provided an excellent method for the preparation of functionally gradient materials with programmed gradients. To test the effectiveness of the method, copolymers made from triethylene glycol dimethacrylate/hexyl methacrylate with linear and hyperbolic gradient in composition were synthesized. Differential scanning calorimetry (DSC), Shore A hardness measurements, compression tests, and swelling studies were performed along the length of the materials to assess the relationship between the gradients and the material properties. Glass transition temperatures, determined by DSC, showed a linear dependence on the composition and were in agreement with theoretical values. The other properties showed different and specific behaviors as a function of the compositional gradient.

The frontal ring opening metathesis polymerization (FROMP) of dicyclopentadiene (DCPD) in the presence of limonene, using second generation Grubbs’ catalysts, is reported. The effect of limonene on the amount of catalyst and the typical frontal polymerization parameters, as maximum temperature (Tmax) and velocity of the front (Vf), is studied. In addition, the influence of limonene on the mechanical properties of the polymeric samples is reported. Finally, a deep study on the swelling properties of polymers is done. It has been demonstrated that limonene acts as both inhibitor and solvent of the catalyst. The Tmax, Vf, Tg, and Young modulus values decrease as the amount of limonene increases, and the polymer samples swell in THF depending on the amount of limonene. All results indicate that the limonene addition on FROMP of results in advantages on the polymerization reaction and its parameters and on the final polymer properties. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 63–68

Precious metals, in particular palladium (Pd), have a wide range of daily applications, from automotive catalysts to fine chemistry production. Nevertheless, these metals are relatively rare and highly expensive, considering their massive industrial utilization. In the last decades, different recycling methods have been explored. Nowadays, the most applied methods, namely pyro-and/or hydrometallurgy, involve energy-intensive processes and/or the generation of large amounts of effluents to be treated. Thus, the development of a more sustainable recycling process of precious metals is highly desirable. In the present work, we introduce a sustainable process based on the use of a green solvent, supercritical CO2, operated under mild conditions (P = 25 MPa and T = 40 °C). The extraction process is possible thanks to the addition of CO2-soluble complexing polymers bearing pyridine units. The proposed method leads to the extraction of more than 70% of Pd from an aluminosilica-supported catalyst.