A polystyrene (PS)/poly(butyl acrylate) (PBA) composite emulsion was produced by seeded emulsion polymerization of butyl acrylate (BA) with PS seed particles which were prepared by emulsifier-free polymerization of styrene with potassium persulfate (KPS) under a nitrogen atmosphere at 70°C for 24 h with stirring at 60 rpm and swelled with the BA monomer in an ethanol/water medium. The structure of the PS/PBA composite particles was confirmed by the presence of the characteristic absorption band attributed to PS and PBA from FTIR spectra. The particles for pure PS and PS/PBA with a low content of the BA monomer were almost spherical and regular. As the BA monomer content was increased, the particle size of the PS/PBA composite particles became larger, and more golf ball-like particles were produced. The surface morphology of the PS/PBA composite particles was investigated by AFM and SEM. The T g 's attributed to PS and PBA in the PS/PBA composite particles were found at 110 and Ϫ49°C, respectively. The thermal degradation of the pure PS and PS/ PBA composite particles occurred in one and two steps, respectively. With an increasing amount of PBA, the initial thermal decomposition temperature increased. On the contrary the residual weight at 450°C decreased with an increasing amount of PBA.

1,1-Dicyclopentadienyl-1-silacycloalkanes (2) were prepared by condensation of cyclopentadiene with appropriate 1,1-dichloro-1-silacycloalkanes [(cycl)SiCl2 (1); cycl = C n H2 n , n = 3, 4, 5]. Dilithium salts of 2 were subsequently transformed into the corresponding ansa-metallocene complexes [{η:5η5-Cp2-(cycl)Si}MCl2] (M = Ti (3), Zr (4), Hf (5)). The molecular structures of 3b, 3c, 4b, and 4c were determined by X-ray crystallography. As a result of the formation of the siladicyclopentadienyl ring, the metal atoms in 3−5 exhibit distorted tetrahedral configurations with the two chloride atoms. DFT calculations established that the size of the bridge ring influenced the catalytic activity. Thus, the catalytic activity of the ansa-titanocene complexes was remarkably enhanced by the silacycloalkyl bridge due to their increased conformational stability (14 × 103 kg PE molcat -1 h-1 for 3c). In addition, polyethylenes with high molecular weight such as M w = (1.3−2.6) × 106 (M w/M n = 1.6−2.0 by GPC) were obtained with 3.

A series of cyclic silylene-bridged (amidocyclopentadienyl)-dichlorotitanium(IV) complexes [TiCl 2 {η 5 -1-(CySitBuN-κN)-2,3,4,5-R 4 -C 5 }] was prepared, where CySi = silacyclobutyl (a), silacyclopentenyl (b), silacyclopentyl (c), and silacyclohexyl (d); R = H (4), Me (5). The starting silane, dichlorosilacycloalkane CySiCl 2 (1), was treated with NaCp (LiCp*), followed by LiNHtBu to yield the cyclic silylene-bridged ligands (R 4 C 5 )CySi(NHtBu) [R = H (2); Me (3)]. Subsequent deprotonation with n-butyllithium, followed by transmetalation with TiCl 4 yielded the desired constrained geometry complexes (CGCs) (CpCySiNtBu)TiCl 2 (4) and (Cp*CySiNtBu)TiCl 2 (5). The structures of the resulting cyclopentadienyl-(4b and 4c) and tetramethylcyclopentadienyl(silacycloalkyl)amidotitanium(IV) dichloride (5a, 5c, and 5d) species were studied by using X-ray crystallography to obtain geometrical information on cyclic silylene-modified CGCs. The ethylene polymerization by the cyclic silylene-bridged