71400-29-8

Upstream product

• 3770-82-9 1,3-dibenzoylbenzene 
• 78-86-4 s-butyl chloride 
• 34241-86-6 1,3-di[(phenyl)-ethenyl]-benzene 
• 598-30-1 sec.-butyllithium 

Downstream Products

• 73137-39-0 (1,3-phenylene)bis(3-methyl-1-phenyl pentylidene) 

Relevant academic research and scientific papers

Synthesis and characterization of model cyclic block copolymers of styrene and butadiene. Comparison of the aggregation phenomena in selective solvents with linear diblock and triblock analogues

The synthesis and characterization of model cyclic diblock copolymers of styrene (St) or perdeuterated styrene (St-d8) and butadiene (Bd) are presented. Since conventional methods of characterization cannot separate completely the cyclic copolymer from its linear precursor, differences in the micellar behavior were used as a method for investigation of their purity. For this purpose, in addition to the cyclic and linear triblock copolymers, two linear diblocks with similar compositions, and molecular weight equal or half of the cyclic diblocks, were also synthesized. The synthetic approach of the cyclics involved the reaction of (1,3-phenylene)bis(3-methyl-1-phenylpentylidene)dilithium initiator with butadiene in the presence of sec-BuOLi, followed by polymerization of St (or St-d8). The cyclization of the resulting α,ω-difunctional triblock copolymer was performed by using bis(dimethylchlorosilyl)-ethane, under high dilution conditions. The copolymers were characterized by size exclusion chromatography, membrane osmometry, NMR and UV spectrometry, and viscometry. The micelles formed in the selective solvents n-decane (for PBd) and dimethylformamide (for PS-d8) were characterized by small-angle neutron scattering and dynamic light scattering. It was found that the aggregation number of the cyclic copolymers was the smallest among the different macromolecular architectures. Moreover, the SANS data for the triblocks in n-decane indicated the presence of 37% dangling chains which did not appear in the data for the corresponding cyclic copolymers. Considering that 5% of dangling chains is possible to be detected, it proves that the cyclic copolymers are at least 87% pure. A scaling model was used in order to justify the difference in the aggregation numbers between the four different copolymers.

Synthesis and characterization of well-defined, regularly branched polystyrenes utilizing multifunctional initiators

A series of well-defined, long-branched polystyrenes (PS) of various architectures, but the same overall molecular weight, suited to the systematic study of branching effects, have been synthesized by anionic polymerization and characterized. Three end-branched, star-branched polystyrenes with 6, 9, and 13 end branches were synthesized with a trifunctional organolithium initiator; the synthesis of the 13-end molecule required a recently developed methoxysilyl functionalization and precipitation procedure to remove excess linking agent. In these architectures the number of branch points was fixed at four, while the number of chain ends varied. A 6-end, pom-pom (dumbbell-shaped) PS with two branch points was synthesized with a difunctional organolithium initiator. A regular 6-arm star polystyrene having one branch point was included to provide a comparison among three polymers, each having 6 ends, but having the number of branch points equal to 1, 2, or 4, The intrinsic viscosities and infinite dilution diffusion coefficients (and therefore the branching factors and hydrodynamic radii) decrease with increasing number of chain ends but do not vary monotonically with number of branch points. The values of Tg for the molecules reflect both the effects of tethering by junction points and increases in free volume due to the multiplication of chain ends as well as the presence of butadiene units used to facilitate linking.

1,3-Bis[1-(4-methylphenyl)ethenyl]benzene

Highly desirable organic liquid soluble multifunctional lithium containing initiators are prepared by reacting an organo lithium compound with an organic compound containing at least one group of the configuration 1,3-bis(1-phenylethenyl)benzene. Such ini