Synthesis of (styrene‐p‐chlorostyrene) tri‐block copolymers and their properties in dilute solutions

Abstract

Two series of well-characterized (styrene-p-chlorostyrene) tri-block copolymers of B,,,A,B,-and A,B,A,-types (A : styrene monomeric unit, B: p-chlorostyrene monomeric unit. n = 2m denotes the number of units) were synthesized by anionic polymerization technique. Their intrinsic viscosities in toluene, 2-butanone, and cumene were studied over a wide range of molecular weights. The data were analyzed on the basis of two-parameter theories. The unperturbed dimensions of the block copolymers are expressed by those of the parent homopolymers and the composition. The conformational behaviours of the B,,,AnB, and A,B,,A, copolymers are similar in the non-selective solvents, toluene and 2-butanone, whereas in the selective solvent, cumene, which is a O solvent for poly-p-chlorostyrene and a good solvent for polystyrene, a molecule of the A,B,,A, copolymers takes a more extended chain conformation and a greater value of the longrange interaction parameter than the B,,,AA,B, copolymers of the same composition. However, an anomaly which suggests "intrachain phase separation" wqs not observed in the viscosity behaviours of the block copolymers in cumene as well as in toluene and 2-butanone. ZUSAMMENFASSUNG :Zwei Reihen gut definierter Dreiblock-Copolymerer aus Styrol (A) und p-Chlorstyrol (B) wurden durch anionische Polymerisation hergestellt. Sie haben die Formen B,-A,-B, und A,-B,-A,, wobei n = 2 m die Anzahl der Monomereinheiten bezeichnet. Ihre Viskositatszahlen in Toluol, 2-Butanon und Cumol wurden in einem groBen Molekulargewichtsbereich untersucht und aufgrund der Zweiparameter-Theorien ausgewertet. Die ungestorten Dimensionen der Blockcopolymeren lassen sich durch die der Homopolymeren und die Zusammensetzung ausdrucken. Das Konformationsverhalten beider Copolymertypen in den nicht selektiven Losungsmitteln Toluol und 2-Butanon ist ahnlich. Im selektiven Cumol, das fur Poly-p-chlorstyrol ein 0-Losungsmittel und fur Polystyrol ein gutes Losungsmittel ist, werden die Knaueldimension und der Parameter fur die weitreichende Wechselwirkung fur die A,-B,-A,-Copolymere groBer als fur die B,-A,-B,-Typen gleicher Zusammensetzung. Es ergaben sich jedoch weder in Cumol noch in Toluol oder 2-Butanon Anomalien im Viskositatsverhalten beider Blockcopolymeren, die auf eine innere Phasentrennung hinweisen.

Anionic living polymerization of functionalized monomers

“…4-Chlorostyrene was reported in 1976 to undergo anionic living polymerization [26]. However, it was pointed out by another research group that undesirable side reactions were observed to occur significantly between the chloride and active chain end during the anionic polymerization [27].…”

Living Anionic Polymerization of 4-Halostyrenes

“…Shima and co-workers reported the anionic polymerization of 1 in THF at −78 °C using oligo(styryl)disodium, followed by the sequential addition of styrene to produce the ABA triblock copolymer, polystyrene-b-poly(1)-bpolystyrene. 33 They mentioned the lower stability of the propagating carbanion derived from 1 than that of living polystyrene. Therefore, the obtained polymer contained the B homopolymer and AB diblock copolymer as impurities resulting from side reactions.…”

“…However, the anionic polymerizability of halostyrenes has not been elucidated and does not satisfy the requirement for evidence of the living anionic polymerization. , There have been several reports on the anionic polymerization behavior of halostyrenes. Shima and co-workers reported the anionic polymerization of 1 in THF at −78 °C using oligo­(styryl)­disodium, followed by the sequential addition of styrene to produce the ABA triblock copolymer, polystyrene- b -poly­( 1 )- b -polystyrene . They mentioned the lower stability of the propagating carbanion derived from 1 than that of living polystyrene.…”

Bubble growth in the microcellular foaming of CO2/polypropylene solutions

“…It has been broadly investigated since 1917. Bubble growth models can be classified into two groups: single-bubble growth models [3][4][5] and cell models. [6][7][8] Zana and Leal 9 investigated the effect of the shear viscosity and surface tension on bubble collapse using a single-bubble growth model.…”