I. Kössler

Cyclo- and Cyclized Diene Polymers. XVIII. Microstructure and Mechanism of Cyclopolymerization of Isoprene and Butadiene with C2H5AlCl2 + TiCl4 Catalyst

Abstract The polymerization of isoprene and butadiene with an ethylaluminum dichloride-titanum tetrachloride catalyst system yields ladder polymers containing fused cyclic structures. Cyclopolymers prepared in n-heptane are generally insoluble powders, while cyclopolymers prepared in aromatic solvents are soluble even when the molecular weight exceeds 1 × 106. In cyclopolyisoprene two phenyl groups are incorporated into the polymer structure per 100 monomer units, independent of molecular weight from 1 × 104 to 2 × 106, while cyclopolybutadiene contains as many as 7–9 phenyl groups per 100 monomer units. The cyclopolymers contain residual unsaturation, 10–40% of which is cycloalkenyl, and methyl groups. Indirect evidence indicates that cyclopolyisoprene may have a perhydrophenanthrene structure. The proposed polymerization mechanism involves cation-radical initiation and propagation. An activated monomer cation radical results from a one-electron transfer from monomer to an electron acceptor species produ...

The Mark-Houwink constants for poly(methyl methacrylate) in N,N-dimethylformamide

SummaryThe Mark-Houwink constants K = 2.5 x 10−2, a = 0.625 were determined for the system poly(methyl methacrylate) — dimethylformamide at 25°C using narrow fractions (Mw/Mn from 1.00 to 1.55) in the molecular weight range from 1.19×105 to 1.94×105 as determined by the light scattering method and osmometrically.

Cyclo- and Cyclized Diene Polymers. XIX. Polymerization of Butadiene with the C2H5AlCl2 + TiCl4 Catalyst

Abstract The polymerization of butadiene with an EtAlCl2-TiCl4 catalyst system yields cyclopolybutadiene with varying amounts of trans-1, 4 units, depending upon the Al/Ti ratio and the solvent. Apparently different active centers are produced at Ti > Al and Al > Ti ratios. When the catalyst system has Ti > Al, there is a rapid decrease in the initial polymerization rate and the cyclopoly butadiene contains large amounts of methyl groups, 10–12% of trans-1, 4 units, 2–3% of 1, 2 units, and, when the polymerization is carried out in aromatic solvents, aromatic moieties are incorporated in the structure. When the catalyst system has Al > Ti, there is a very slow decrease of the initial polymerization rate, and the cyclopoly butadiene contains up to 40% of trans-1, 4 units, less than 1% of 1, 2 units, and methyl groups and solvent moieties are essentially absent even when the polymerization is carried out in aromatic solvents. Cocatalytic amounts of iodine greatly increase the initial rate of polymerization....

Oxidation of Poly(2,3-dimethylbutadiene-1,3)

Abstract Poly(2,3-dimethylbutadiene-1,3) containing cis-1,4, trans-1,4, and 1,2 structural units in various proportions undergoes rapid oxidation even at room temperature. The process of oxidation is accompanied by cyclization. The concentration of peroxides that form at room temperature is relatively very high, reaching the value of one peroxidic group per 16 monomeric units. The formation of six-membered rings involving the peroxidic bonds in poly(2,3-dimethylbutadiene) is accompanied by degradation.

Cyclopolymers and Cyclopolymerization

Abstract The polymer literature now includes more than 500 papers dealing with cyclopolymerization and cyclopolymers, the first having appeared in 1957. A wide variety of dienes have been shown to undergo cyclopolymerization. In fact, almost all of the 1,6-dienes corresponding to the well-known vinyl monomers have now been synthesized and studied. Many of the corresponding 1,5-dienes which lead to five-membered rings on cyclopolymerization have also been synthesized and studied. In addition, both homopoly-mers of 1,4-dienes, which lead to bicyclic structures, and copolymers of 1,4-dienes with monoolefins have been synthesized and studied. Essentially all known methods of initiation of vinyl polymerization have now been used in conjunction with specific dienes in cyclopolymerization. In fact, one monomer, 2,6-diphenyl-l, 6-hexadiene, has been shown to undergo cyclopolymerization to form essentially the same polymer by anionic, radical, cationic, and coordination initiation.

Gradient dependence of viscosity of cellulose tricarbanilate in tetrahydrofuran

SummaryThe dependence of viscosity of cellulose tricarbanilate in tetrahydrofuran on the velocity gradient D <2500 s−1 for molecular weights up to 1.2×106 was determined, and an empirical equation for the determination of the limiting viscosity number for zero velocity gradient was derived. Errors involved in the viscosity determination from a single concentration using an approximate formula were also ascertained.