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Abstract: A well-dispersed multiwall carbon nanotube (MWCNT)/syndiotactic polystyrene (sPS) composite was prepared by simple in-situ polymerization of styrene using pentamethylcyclopentadienyltitanium(IV) trimethoxide (Cp*Ti(OMe)3) attached to the shortened and functionalized MWCNT (f-MWCNT). The attachment of Cp*Ti(OMe)3 to the f-MWCNT was confirmed by thermogravimetric analysis, X-ray photoelectron spectroscopy, Fourier transformed infrared spectroscopy, and energy dispersive X-ray spectroscopy. Cp*Ti(OMe)3 attached to pristine MWCNT in the presence of methylaluminoxane (MAO) did not produce PS, whereas Cp*Ti(OMe)3 attached to f-MWCNT showed a high catalytic activity for the syndiospecific polymerization of styrene under the same polymerization conditions. Obtained sPS showed a narrow molecular weight distribution (PDI ≈ 2), a high SI value (≥90%), and a high melting point (≈272 °C). Scanning electron microscopy and transmission electron microscopy images showed that MWCNT strands were well dispersed in the MWCNT/sPS composite. Such composites had greatly improved thermal stability compared to normal sPS polymers. [Copyright &y& Elsevier]

Abstract: Tris(4-hydroxy-3,5-diisopropylbenzyl)amine (LH3 ) was synthesized by the reaction of 2,6-diisopropylphenol and hexamethylenetetramine in the presence of p-toluenesulfonic acid or paraformaldehyde. Its solid state structure was determined by single crystal X-ray diffraction. Its fully deprotonated specie, (4-O-3,5-i-Pr2PhCH2)3N (L), was used to form novel trinuclear half-sandwich titanocene complexes, namely [(η5-C5Me5)TiCl2]3L (1) and [(η5-C5Me5)Ti(OMe)2]3L (2), which were then tested for the syndiospecific polymerization of styrene in the presence of methylaluminoxane (MAO) cocatalyst. Their catalytic properties were directly compared with those of trichloro(pentamethylcyclopentadienyl)titanium(IV) (3) and dichloro(2,6-diisopropylphenolato)(pentamethylcyclopentadienyl)titanium(IV) (4). 1/MAO and 2/MAO systems showed higher activities towards styrene polymerization than the mononuclear catalytic systems 3/MAO and 4/MAO, giving syndiotactic polystyrene of high molecular weight. [Copyright &y& Elsevier]