This study demonstrates the low temperature synthesis ofα-Al2O3by solvothermal method using gibbsite alumina precursor in 1, 4-butanediol solvent according to various pH conditions. In acidic solution, an orthorhombic boehmite (AlOOH) structure was obtained after solvothermal reaction. A significant result in this study was that the solvothermally synthesized alumina inpH=9at 300 °C for 36 h represented a rhombohedralα-Al2O3structure hexagonal shaped with about 1.5~2.0 μm of particle size. Otherwise, theα-Al2O3structure was rather changed to the mixture of a boehmite andα-Al2O3structures abovepH=11. In the case ofα-Al2O3synthesized atpH=9, the specific surface area was 26.18 m2/g, and the particles that were stable in acidic solution resulted in 61.80 mV of zeta potential.

A series of bis(β-ketoimino)nickel(II) complexes with p-substituted N-phenyl groups, Ni[CH 3 C(O)CHC(NPhR)-CH 3 ] 2 (Ni1: R = −OCH 3 ; Ni2: R = −CH 3 ; Ni3: R = −CF 3 ), were synthesized, and their general coordination geometry was elucidated by single-crystal X-ray diffraction analysis of Ni3. These complexes were paired with tris(pentafluorophenyl)borane (B(C 6 F 5 ) 3 ) to catalyze the vinyl addition copolymerization of norbornene (NB) and methyl 5-norbornene-2-carboxylate (NBE). All the catalyst systems exhibited high catalytic activities (>10 5 g polymer mol Ni −1 h −1 ) at NBE feed contents of up to 50 mol %, resulting in the production of copolymers with high molecular weights (M w = 135−355 kg mol −1 , Đ = 1.78−2.12). In addition, the content of polar ester groups was precisely controlled by the feed ratio of the monomers. For Ni3, two monomer reactivity ratios were found to be close to unity (Fineman−Ross method: r NB = 0.951, r NBE = 0.903; Kelen−Tudos method: r NB = 1.15, r NBE = 0.978). Since the copolymerization behaviors were revealed to be independent of the electronegativity of p-substituent, all the catalyst systems of Ni1−Ni3/B(C 6 F 5 ) 3 were considered to serve the random copolymerization of NB and NBE. The resulting poly(norbornene-random-methyl 5-norbornene-2-carboxylate)s exhibited the dielectric and surface properties well tunable by compositional modulation.