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Palladium(II) complexes with the formula [Pd(H2O)(OTs)(P-P)]OTs, where P-P is 1,1‘-bis(dimethylphosphino)ferrocene (dmpf), 1,1‘-bis(diethylphosphino)ferrocene (depf), or 1,1‘-bis(diisopropylphosphino)ferrocene (dippf), have been synthesized and used to catalyze the carbonylation of ethylene in MeOH, water, or a 1/1 water/1,4-dioxane mixture. In MeOH, the reactions catalyzed by the dmpf and depf complexes gave alternating polyketone (alt-E-CO), while methyl propanoate and 3-pentanone were selectively produced with the dippf catalyst. The last catalyst was inactive in aqueous solvent. In contrast, the dmpf and depf catalysts were active in either water or water/1,4-dioxane for the copolymerization of CO with ethylene. These two catalysts were efficient also for the terpolymerization of CO with ethylene and propene in MeOH or water/1,4-dioxane. Operando high-pressure NMR experiments and in situ reactions with model compounds have provided useful information to rationalize the activity and selectivity of the catalytic systems investigated.

Isotactic polypropylene (iPP) gives very extensive degradation when treated with peroxides above its melting temperature in mechanical mixers or extruders. This undesired reaction is very modestly affected by maleate molecules which on the contrary actively compete with side reactions of macroradicals in the case of ethylene polymers. In this work iPP was treated in a Brabender mixer at 180 °C with peroxide and different selected molecules capable of promptly reacting with the macroradical formed on iPP chain and converting it into a more stable free radical. Furan derivatives, successfully used for iPP cross-linking without any remarkable increase of MFR, were used as free radical removers and maleic anhydride as functionalizing monomer. The results indicate a detectable improvement with respect to the use of maleic monomers and peroxide only, allowing to us get a significant grafting of functional groups and only partial degradation. Moreover, furan derivatives bearing various reactive substituents were used as functionalizing molecules. The results are discussed in the frame of the general mechanism proposed for the free radical functionalization of polyolefin in the melt.

Several new terthiophene-based, highly anisotropic chromophores were synthesized and dispersed in ultrahigh molecular weight polyethylene (UHMWPE). The chromophores were axially oriented by drawing the polymer matrix and showed an extremely pronounced dichroic behavior. In a pseudo-affine deformation scheme the dyes did well approximate the ultimate properties in terms of molecular orientation; on the other hand, the observed thermochromism and other experimental evidence indicated the persistence of a phase segregation from the polymer matrix.

The thermal degradation behavior of E−CO alternating copolymers submitted to a variety of thermal conditions, both in a vacuum and in an inert atmosphere, has been investigated. The products obtained in the different thermal treatments were analyzed by GC/MS, and the structural changes occurring in the polymer chains were followed by FTIR and UV−vis. The influence of initial degradation reactions on polymer morphology was investigated with DSC, and it was found that thermally induced polymer degradation initiates in the amorphous parts of the samples. The initial reactions involve intramolecular cyclizations which produce cyclopentenone, furanic and oxydrylated structures in the chains, and intermolecular condensations causing cross-linking of polymer chains. Water is the only volatile product formed in this step. When chain scissions start developing, monomers and low molecular weight ketones are obtained as decomposition products. At higher temperatures the degradation embraces the whole polymer and proceeds with a competition of chain scissions, cyclizations, and cross-linking reactions involving macroradicals. The numerous fragments obtained from complete polymer degradation reflect the large structural modifications of the polymer chains.

The polymerizability of 4-vinylazobenzene; (VAB), a vinyl monomer containing an azobenzene chromophore directly attached to the polymerizable double bond, was investigated in the presence of radical, anionic, cationic, and Ziegler−Natta type catalysts. The homo- and copolymerization of VAB with (−)-menthyl methacrylate, carried out in the presence of AIBN as a radical initiator, afforded a fairly high yield of photochromic polymeric materials. On the contrary, no high molecular weight product was formed in the presence of cationic, anionic, and anionic coordinate catalysts, whereas polymeric products were obtained by anionic copolymerization of VAB with styrene. Determination of ¹³C relaxation times allowed us to evaluate the poly(VAB) molecular mobility, also, in comparison, that of 4-isopropylazobenzene, a low molecular weight model compound, and of other polymeric systems containing azobenzene chromophores spaced from the main chain. Thermally and photoinduced trans → cis and cis → trans isomerization rates were almost independent of molecular weight and chemical composition of the investigated samples, thus suggesting that azobenzene isomerization implies an in-plane inversion of the phenyl ring most distant from the polymer backbone. Asymmetric perturbation of the azobenzene chromophores, attributable to the presence of short ordered segments along the polymer chain of MnMA/VAB copolymers, was evidenced by circular dichroism. The limited dependence of the intensity of dichroic bands on copolymer composition was interpreted in terms of distribution and mobility of VAB units.

Optical storage properties of thin unoriented liquid crystalline and amorphous side-chain azobenzene polymethacrylate films are examined by polarization holographic measurements. The investigated materials are free radical copolymers derived from two photochromic monomers, 6-(4-oxy-4‘-cyanoazobenzene)hex-1-yl methacrylate and 8-(4-oxy-4‘-cyanoazobenzene)oct-1-yl methacrylate, and a nonphotochromic optically active comonomer, (−)-menthyl methacrylate. The thermal behavior and phase transitions of the polymers have been investigated in detail through differential scanning calorimetry and polarizing optical microscopy. Atomic force microscopy investigations have been carried out on the polarization holographic gratings recorded in the polymethacrylate films. A surface relief grating has been found to appear in all films after irradiation. The copolymers with 50−75% dye content exhibit the largest surface relief. The stored information seems to be stable up to approximately 70 °C, except in the case of polymers with low dye content.