Polymerisationsgleichgewichte abgewandelter α‐methylstyrole

Abstract

Herrn Kollegen RUDOLF SIGNER sum 60. Geburtstag gewidmet (Eingegangen am 21. Januar 1963) ZUSAMMENFASSUNG:Einige modifizierte a-Methylstyrole wurden hergestellt und mit Naphthalinnatrium polymerisiert. m-und p-substituierte a-Methylstyrole wie p-Isopropenyldiphenyl und p-Isopropenylnaphthalin verhalten sich wie das a-Methylstyrol selbst. Sie sind unterhalb ihrer Ceiling-Temperatur polymerisierbar, wobei sich Monomer-Polymergleichgewichte einstellen, die ausgemessen wurden. Aus diesen Messungen lassen sich die Polymerisationsw*men und die Polymerisationsentropien in bekannter Weise berechnen. Obwohl die Gleichgewichtslagen der einzelnen Monomeren eindeutig verschieden sind, kann nicht mit Sicherheit entschieden werden, ob dies auf eine dnderung der Enthalpie oder der Entropie der Polymerisation zuriickzufiihren ist. o-substituierte a-Methylstyrole wie 2,4-Dimethyl-a-methylstyrol und I-Isopropenylnaphthalin konnten nicht polymerisiert werden. Offensichtlich erhoht o-Substitution die sterische Hinderung im Makromolekiil auaerordentlich. Das gleiche gilt fur das 1,l-Diphenylathylen. SUMMARY:Some modified a-methylstyrenes were prepared and polymerised with sodium ndphthalene. m-and p-substituted a-methylstyrenes like p-isopropenyldiphenyl and P-isopropenylnaphthalene behave like a-methylstyrene. They polymerise below their ceiling temperature, giving monomer-polymer-equilibria, which were measured. Heats and entropies of polymerisation were calculated from these measurements, using known methods. While the equilibrium concentrations for the three monomers are clearly different, it could not be decided whether this is due to differences of the enthalpies or of the entropies of polymerisation. o-substituted a-methylstyrenes, like 2,4-dimethyl-a-methylstyrene and a-isopropenyl naphthalene could not be polymerised. Obviously o-substitution raises the steric hindrance in the macromolecules exceedingly. The same is valid for 1,l-diphenyl ethylene.

Anionic Polymerization of Monomers Containing Functional Groups. 12. Anionic Equilibrium Polymerization of 4-Cyano-α-methylstyrene

“…A number of studies have been so far directed to the thermodynamic and kinetic behaviors in the anionic equilibrium polymerization of α-methylstyrene, − while those of substituted α-methylstyrenes have been quite limited. Actually, although the thermodynamic constants of 4-isopropyl-, 4- tert -butyl-, and 4-phenyl-α-methylstyrenes have been reported under equilibrium conditions, no information is available on the kinetic parameters, molecular weights, MWDs, and particularly the living character of the polymerization system. Recently, similar equilibrium polymerizations of α-methylstyrenes para -substituted with bis(diethylamino)phosphino, 2-(( tert -butyldimethylsilyl)oxy) ethyl, and bis(trimethylsilyl)methyl groups have been individually investigated, and partial deactivations of the propagating carbanions during the polymerizations suggested from the analyses of M n 's and MWDs in the latter reports. , Only one report 26 deals with the satisfactory kinetic study of polymerizations other than that of α-methylstyrene itself. ,− In addition to the thermodynamic studies, careful analyses on the kinetics and the molecular characteristics should also be needed to discuss the polymerization behavior of these α-methylstyrenes containing functional groups essentially susceptible to the side reactions.…”

Living Anionic Polymerization of 4‐(1‐Adamantyl)‐α‐Methylstyrene

“…The anionic polymerization system of α‐methylstyrenes usually shows equilibrium behaviors known as the thermodynamically reversible polymerization due to the steric strain caused by the α‐methyl group . The polymerization of AdαMS was first carried out with K‐Naph in THF at −78 °C for 8 h in order to achieve the complete consumption of monomer similar to the previous experiment (run 5).…”

“…In this study, we newly designed and anionically polymerized an adamantyl‐substituted α‐methylstyrene derivative, 4‐(1‐adamantyl)‐α‐methylstyrene ( AdαMS ), in order to check the polymerizability of the monomer and the thermal properties of the resulting polymer. It is well known that α‐methylstyrene derivatives usually undergo the equilibrium polymerization under the anionic conditions due to the low ceiling temperatures . The polymerization and depolymerization of α‐methylstyrene derivatives reversibly occur under the equilibrium conditions.…”

“…The anionic polymerization system of α-methylstyrenes usually shows equilibrium behaviors known as the thermodynamically reversible polymerization due to the steric strain caused by the α-methyl group. [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] The polymerization of AdαMS was first carried out with K-Naph in THF at −78 °C for 8 h in order to achieve the complete consumption of monomer similar to the previous experiment (run 5). Then, the polymerization temperature of the system was raised to room temperature and the system was stood for 20 h. The characteristic red color of the polymerization system was maintained at room temperature until the termination with methanol.…”

“…It is well known that α-methylstyrene derivatives usually undergo the equilibrium polymerization under the anionic conditions due to the low ceiling temperatures. [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] The polymerization and depolymerization of α-methylstyrene derivatives reversibly occur under the equilibrium conditions. In addition, the poly(α-methylstyrene)s generally show higher T g values than those of the corresponding polystyrene derivatives and the ease of the chain degradation on heating.…”