Thermal characterization was carried out on highly stereoregular and regioregular syndiotactic polypropene (sPP) obtained with isopropylidene(cyclopentadienyl)(9-fluoreny~)~rcoNum dichloride and methylaluminoxane. The influence of molecular weight and syndiotacticity degree on the thermodynamic melting point (T;) of sPP were separately investigated by examining samples with a fully syndiotactic pentads content (rrrr) ranging from ca. 81 070 to ca. 94% and with an weight-average molecular weight (a,,,) ranging from 9,6 -lo4 to 17,3 lo4. Upon excluding any influence of the molecular weight, the correlation between the rrrr pentads content and the T", of the samples led to the extrapolation of the thermodynamic melting point for a fully syndiotactic polypropene.CCC 0025-1 16)

No abstract

No abstract

Controlled functionalization of graphene layers is one of the most important research objectives in the material chemistry. A well established procedure is the oxidation with strong acids and oxidizing agents often in harsh and dangerous reaction conditions giving products of unknown precise structure. In this chapter, the controlled functionalization of graphene layers with a derivative of serinol is presented, avoiding toxic reagents and dangerous reaction conditions. The derivative is the bio‐based serinol pyrrole, obtained through the neat reaction of serinol with 2,5‐hexanedione; the graphitic substrate was high surface area graphite (HSAG) with high‐shape anisotropy. The functionalization reaction, characterized by a 85% atomic efficiency (water is the only by‐product), evolved with high yields leading to functionalized graphene layers through the controlled introduction of oxygen and nitrogen‐containing functional groups. Sustainable processes were adopted, such as ball milling and heating. The mechanism pathway, the characterization of HSAG and reaction products through a wide range of analytical methods, some successful applications of the adducts are discussed in this chapter. The functionalization left the bulk crystalline structure of the layers substantially unaltered. Stable dispersions in water and eco‐friendly solvents were prepared

As reported in the literature homogeneous catalytic systems based on isopropylidene(cyclopentadieny1) (9-fluorenyl)zirconium dichloride (Me,C(Cp)(9-Flu)ZrCI, and methylaluminoxane promote not only the syndiotactic-specific polymerization of propene but also the syndiotactic polymerization of linear (e. g. l-butene)'*') and /3branched a-olefins (e. g. 4-methyl-I -pentene) ' 9 ').In the presence of the quoted catalyst both (S)-4-methyI-l-hexene and racernic-4methyl-1 -hexene afford stereoregular crystalline polymers. The X-ray diffraction spectra and the I3C NMR spectra of poly[(S)-4-methyl-l-hexene] (sample a) and poly[(R) (S)-4-methyl-l-hexene] (sample b) are reported in Figs. 1 and 2, respectively. A comparison of the I3C NMR spectra with those of samples of the corresponding polymers obtained in the presence of isotactic-specific catalysts based on (dimethylsilylene)bis(l-indeny1)zirconium dichloride (Me,SiIn,ZrCl,) [isotactic poly[(S)-4-methyl-1 -hexenel, sample c] and TiCI, /MgCI, /A1 (i-C4H9)' [isotactic poly[(R) (S)-4-methyl-l-hexene], sample d] shows that samples a and b are not isotactic but reasonably syndiotactic as expected in view of the catalyst used for promoting the polymerization. The most interesting feature of the I3C NMR spectrum of sample a is the presence of two resonances of equal intensity at 40,4 and 40,6 ppm from HMDS (hexamethyldisiloxane) arising from methylene carbons. Each resonance has, approximately, one half of the intensity of the resonances of the other carbons of the monomer unit drawn in the following scheme: Scheme 1: 2 1 -CH-CH2-3 CH, 4 CH-CH, 5 CH, 6 CH,