1,2-Polybutadiene molecular characterization

The aim of this research was therefore to extend fundamental investigations on the preparation and molecular characterizations, structures, and functional properties of both of the bulk and the surface of A-B-A tri-block copolymer membranes in which A is a polypeptide and B is polybutadiene or polytetramethyleneoxide. 

Chen, G.W., Hayashi, T, and Nakajima, A. (1981) Synthesis and molecular characterization of A-B-A tri-block copolymers composed of poly(Y-ethyl L-glutamate) as the A component and polybutadiene as the B component. Polymer Journal, 13,433-442. 

An unusual method for the preparation of syndiotactic polybutadiene was reported by The Goodyear Tire Rubber Co. (43) a preformed cobalt-type catalyst prepared under anhydrous conditions was found to polymerize 1,3-butadiene in an emulsion-type recipe to give syndiotactic polybutadienes of various melting points (120—190°C). These polymers were characterized by infrared spectroscopy and nuclear magnetic resonance (44—46). Both the Ube Industries catalyst mentioned previously and the Goodyear catalyst were further modified to control the molecular weight and melting point of syndio-polybutadiene by the addition of various modifiers such as alcohols, nitriles, aldehydes, ketones, ethers, and cyano compounds. 

Polybutadiene-polydimethylsiloxane segmented copolymers were prepared by the reaction of epoxy-terminated PDMS and carboxy-terminated polybutadienes, in refluxing toluene under catalytic action of potassium hydroxide 243). Molecular weights of the copolymers obtained were usually in the low range. No other characterization data were available. 

Shen and Kaelble (29) found the same linear dependence in the region —60° and 60°C but state that below —50°C and above 80°C the temperature dependence of Kraton 101 could be described by the WLF equation with cx = 16.14, C2 = 56, and Tr — — 97°C below —50°C, and Tr — 60°C above 80°C. They ascribe the temperature dependence below —50 °C to the pure polybutadiene phase and that above 80 °C to the pure polystyrene phase. They then assume that at temperatures between —50° and 80°C the molecular mechanisms for stress relaxation are being contributed by an interfacial phase visualized as a series of spherical shells enclosing each of the pure polystyrene domains and characterized... 

Using the same procedure Pennisi and Fetters prepared a series of asymmetric polybutadiene (PB) stars in which the third arm was of variable molecular weight [2]. It was found more efficient to add the living PB solution to the meth-yltrichlorosilane linking agent in order to reduce the formation of the coupled byproduct. Similar characterization techniques were also employed in this case. 

Polyisobutylene of low molecular weight was synthesized by a Wurtz type reaction from l,4-dibromo-2,2,3,3 tetramethylbutane. Polyacrylates were obtained from alternating copolymerization of symmetric internal olefins or ethylene with maleic anhydride followed by quantitative esterification. Poly(vinyl halides) were prepared from cis-1,4-polybutadiene by chlorination (H-H PVC) or bromin-ation (H-H PrBr). The polymers were characterized and their chemical, thermal, degradation solution, melt and blending behavior was studied. 

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