摘要:
Disclosed is a process for preparing polymers and copolymer blocks of conjugated dienes with high amounts of branching, commonly referred to as vinyl content, comprising the use of at least two microstructure control agents. One of the microstructure control agents can be a bulk microstructure control agents such as diethyl ether. The other microstructure control agent is a specific microstructure control agent such as 1,2-diethoxypropane. The use of a bulk and a specific microstructure control agent together can allow for the production of high levels of vinyl content at high polymerization rates without the undesirable affects experienced with either one alone.
摘要:
This invention relates to solid secondary alkyl sulfate/zeolite-containing surface active compositions which are formed by crystallization and which contain at least about 80 percent by weight of secondary alkyl sulfate and zeolite. These compositions are substantially free of unreacted organic matter and water. The invention further relates to a process for preparing these solid secondary alkyl sulfate/zeolite-containing compositions.
摘要:
A method for separating a biological conjugate from an aggregate. The molecular weight of the biological conjugate ranges from about 10 kDa to about 1000 kDa. In one embodiment, the method comprises the steps of: (e) providing a mixture comprising the biological conjugate and the aggregate, wherein the biological conjugate has a molecular weight of from about 10 kDa to about 1000 kDa; (f) providing a chromatography column containing a gel, wherein the gel comprises at least one polysaccharide; (g) introducing the mixture of step (a) into the chromatography column; (h) recovering the biological conjugate from the column.
摘要:
Disclosed is a method for making selectively hydrogenated block copolymers of vinyl aromatic hydrocarbons and conjugated dienes comprising: a) anionically polymerizing vinyl aromatic hydrocarbons and conjugated dienes to produce block copolymers with living chain ends; b) terminating the living chain ends; to produce a terminated block copolymer, with a member from the group consisting of an alcohol, hydrogen, and mixtures thereof, to prepare a terminated block copolymer; and c) contacting the terminated block copolymers with hydrogen at a temperature of from 20 to 175° C. in the presence of a catalyst prepared by combining a cobalt carboxylate with an aluminum alkyl, wherein: (i) if the polymer is terminated with an alcohol and the alcohol is a linear alcohol, the linear alcohol is used to terminate the living chain ends in an amount such that the alcohol:living chain end molar ratio is from 0.05 to 1.2: (ii) if the polymer is terminated with an alcohol and the alcohol is a branched alcohol, the branched alcohol is used to terminate the living chain ends in an amount such that the alcohol:living chain end molar ration is from 0.05 to about 3.0: an (iii) if the polymer is terminated with an alcohol and the alcohol is a mixture of a linear alcohol and a branched alcohol, the linear alcohol is used to terminate the living chain ends in an amount such that the linear alcohol:living chain end molar ration is from 0.05 to 1.2.
摘要:
This invention relates to solid secondary alkyl sulfate-containing surface active compositions which are formed by crystallization and which contain at least about 80 percent by weight of secondary alkyl sulfate. These compositions are substantially free of unreacted organic matter and water. The invention further relates to a process for preparing these solid secondary alkyl sulfate-containing compositions.
摘要:
A process is provided for modifying the properties of a hydrophobic microporous membrane which includes the steps of first providing a hydrophobic microporous membrane, treating it with a surfactant to render the membrane hydrophilic, wetting the membrane with an aqueous solution of a polyol such as polyvinyl alcohol (PVA) and divinyl sulfone (DVS) or a precursor thereof, washing the membrane with water to displace the polyol/DVA from the exterior of the membrane while retaining it in the pores of the membrane, and crosslinking the polyol/DVS into an aqueous gel to yield a hydrophilic microporous membrane having pores filled with an aqueous polyol/DVS gel, the exterior of the membrane being unobstructed by gel. The modified membranes produced according to the process are useful in carrying out chromatographic separations.