Abstract: A process for preparing olefinic living polymers having a molecular weight distribution (Mw/Mn) of 1 to 1.3, comprising polymerizing an olefinic monomer having 2 to 20 carbon atoms at low temperatures in the presence of a catalyst comprising (A) a hafnium or zirconium-containing compound having one or two cyclopentadienyl backbones, (B) a triphenyl boron compound or a tetraphenyl borate compound and optionally (C) a specific mono-, di- or trialkylaluminum compound. When the catalyst comprising the zirconium-containing compound is prepared by further using a titanium-containing compound (D), the polymerization temperature can be raised.

Abstract: A butadiene polymer (i) having a cis bond unit content of at least 50% based on the total butadiene units, a number average molecular weight (Mn) of 1,000 to 10,000,000, and at least 80%, based on the total molecular chains, of living chains containing a transition metal of group IV of the Periodic table at a terminal thereof; a polymer (ii) obtained by modifying terminals of the polymer (i); and a polymer (iii) obtained by coupling the polymers (i). These polymers (i), (ii) and (iii) are obtained by polymerizing a conjugated diene monomer alone or with a copolymerizable monomer at a specific temperature in the presence of a catalyst comprising a compound (A) of a transition metal of group IV of the periodic table having a cyclopentadienyl structure and a co-catalyst (B) selected from organoaluminum-oxy compound (a) and others and optionally further by contacting the resultant polymer with a terminal modifier or a coupling agent.

Abstract: A catalyst comprising an organoaluminum compound and a vanadium chelate compound having the lability to cause olefins to undergo living coordination polymerization is contacted with a terminal diolefin to obtain a catalyst for living polymer production. When the above contact is:conducted in the presence of a cycloolefin or an internal olefin, the yield of a living polymer can be improved. By modifying all ends of the living polymer obtained, a telechelic olefin polymer is obtained in which all the polymer chains are modified with functional groups.

Abstract: A process is disclosed for preparing of aromatic polyester-polystyrene block copolymers which comprises subjecting preferentially styrene polymers (A) having terminal functional groups reactive with acid chloride groups and an excess of aromatic dicarboxylic acid dihalides (C) to condensation and then subjecting continuously the resultant mixture and aromatic dihydroxy compounds (B) to interfacial polymerization at the ratio (A)/[(B)+(C)] by weight of 5/95 to 80/20, without separating reaction products of styrene polymers (A) and aromatic dicarboxylic acid dihalides (C), and the block copolymers thus prepared contain a small amount of uncopolymerized styrene polymers, have long aromatic polyester segments, show low birefringence, good transparency, exceptionally low birefringence, low melt viscosity, and good mechanical strength, and are particularly useful as materials for optical instruments.

Abstract: A process is disclosed for the preparation of aromatic polyester-polystyrene block copolymers by solution polycondensation of styrene polymers (A) having terminal functional groups reactive with acid halide or hydroxyl groups, aromatic dihydroxy compounds (B), and aromatic dicarboxylic acid dihalides (C) at (A)/[(B)+(C)] (by weight) of 5/95 to 80/20 and the polymers are suitable as molding materials for optical instruments for their good transparency, particularly low birefringence, low melt viscosity, and good mechanical strength.

Abstract: An aromatic polyester carbonate comprising structural units represented by the following formulae (A), (B), (C), and (D) and satisfying the following relationship when the mole fractions of the structural units represented by the formulae (A), (B), (C), and (D) are defined as a, b, c, and d, respectively: ##EQU1## and having an inherent viscosity [.eta..sub.inh ] in a solution at a concentration of 0.5 g/dl in p-chlorophenol as a solvent at 50.degree. C. of 1.0 dl/g or higher, or being insoluble in the solvent, and having liquid crystal properties ##STR1## wherein R is the same or different and represent an alkyl, phenyl group or a halogen, and n represents an integer of 0 to 4; ##STR2## X.sup.1 represents a substituted or non-substituted phenyl group, an alkyl group having 3 to 6 carbon atoms or a halogen;X.sup.2 represents --O--, --S--, ##STR3## or --CH.sub.2 --; X.sup.3 may be the same or different and represents an alkyl group, phenyl group, or a halogen; and m represents an integer of 0 to 4.