The Association Behavior of Polystyryllithium, Polyisoprenyllithium, and Polybutadienyllithium in Hydrocarbon Solvents

Abstract

at the present time. Preliminary X-ray studies of the triblock polymers under stress indicate very marked changes in all of the scattering peaks. However, the interpretation is no longer as simple as in the above experiments.

Microstructure effect in the coupling reactions of polymeric organolithium compounds using chlorosilanes

“…It is essential that the coupling yields of poly(dienyl)lithiums in hydrocarbon by addition of Lewis bases. 34,45,[47][48][49][50][51] To investigate the microstructure effect of polyshould be higher or similar to those of poly(styryl)lithium. It has been well known for (dienyl)lithium in the coupling reactions with silane-coupling agents, we first synthesized polya long time that linking reactions of polymeric organolithium compounds with silane-coupling (styrene-b-dienyl)lithium through block copolymerizations of styrene and dienes.…”

Kinetics of Living Anionic Polymerization of Polystyrenyl Lithium in Cyclohexane

“…After full conversion of the propagation (achieved by keeping the NMR tubes, after the above measurement, at room temperature for $ 1 d), 7 Li NMR measurements were conducted for some batches at several temperatures with a JEOL JNM-AL400 spectrometer. A static magnetic field was set at 9.4 T, and the resonance frequency was 153.86 MHz.…”

“…The pulse width (flip angle), pulse repetition, and number of scan were 7.2 ms (45 deg), 0.5 min, and 6400 (or 4096 for a few cases), respectively. The measured 7 Li spectra, expressed as the value relative to a 0.2 M LiCl/D 2 O solution (reference system), reflected the rate of the Li-Li exchange between the polymerized hPSLi chains.…”

“…This barrier can be examined through the 7 Li NMR spectra that reflect the Li-Li exchange of these aggregates. As an example, Figure 11 shows the spectra measured at 34.5 C for the batches 11(0.05,0), 16(0.13,0), and 16(0.05,0.10) after completion of polymerization.…”

“…4,11,15,16 The aggregation occurs not only for the initiators but also for the polymerized anionic chains in nonpolar solvents. Scattering/viscosity experiments revealed that the anionic chains form aggregates with the main aggregation number f being determined by the chemistry of the anionic ends: [1][2][3][4]7,12,[16][17][18][19][20][21][22] For example f ¼ 2 for polystyrenyl lithium chains in the range of the molecular weight 10 < 10 À3 M < 200. The aggregation number has a distribution (for example, ranging mainly from 3 to 5 for polybutadienyl lithium in cyclohexane) 21 and a trace amount of huge aggregates (with the aggregation number !…”