Homogeneous anionic polymerization of unsaturated monomers

Morton, Maurice; Fetters, Lewis J.

doi:10.1002/pol.1967.230020103

Cited by 61 publications

(14 citation statements)

References 263 publications

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“…K e n que l'appareil utilis6 s'inspire de diffhrentes conceptions bribvement d6crites prBc6dem-ment20~25~26) et que des conditions exp6rimentales variBes15~16,21~22, 27) assurent un Bgal succbs quant ii 1'homBodispersitB des produits obtenus, une description detaillee apparaPt nhanmoins nhcessaire en raison de la spkcificit6 du travail effect& ici (Appendice I). K e n que l'appareil utilis6 s'inspire de diffhrentes conceptions bribvement d6crites prBc6dem-ment20~25~26) et que des conditions exp6rimentales variBes15~16,21~22, 27) assurent un Bgal succbs quant ii 1'homBodispersitB des produits obtenus, une description detaillee apparaPt nhanmoins nhcessaire en raison de la spkcificit6 du travail effect& ici (Appendice I).…”

Section: Analyse Des Conditions De Synth2seunclassified

Synthèse anionique de polystyrènes ramifiés en éatoile à quatre et six branches

Meunier

Leemput

1971

Makromol. Chem.

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Synthhse anionique de polystyrhes ramifies en &toile a quatre et six branches Par JEAN-CLAUDE MEUNIER *) et ROBERT VAN LEEMPUT (Eingegangen am 29. Mai 19'70) RESUME : Les Bchantillons de polystyrknes ramifies en Btoile A 4. et 6 branches sont synthetisks par polymerisation anionique 5 -78OC dans le t6trahydrofuranne par l'action du sec-butyllithium et la desactivation des chaines carbanioniques sur divers agents de couplage. Une substitution complete intervient avec le 1.2.4.5-t&tra(chlorom~thyl)benzbne et l'hexa[p-(chlorom6thyl)ph6nyl]benzkne sans produit de fonctionnaliti5 intermi5diaire. Dans les m6mes conditions, le trimere et le tetramiire cycliques du chlorure de phosphonitrile induit certaines reactions secondaires, tandis que l'hexa[p-(dichlorom~thyl)phCnyl]benz~ne ne fournit qu'un polymbre lineaire de masse moleculaire double. La separation des differentes espbces branch& est realis6e i grande Bchelle par la methode chromatographique de BAKER et WILLIAMS. Les conditions de synthkse, les reactions secondaires du couplage ainsi que les resultats des fractionnements sont discuti5s. ZUSAMMENFASSUNG : Sternvereweigte Polymere des Styrols mit 4 und 6 Verzweigungen wurden durch Desaktivierung von Polystyryllithium, das bei -78°C in THF rnit sek.-Butyllithium hergestellt worden war, mit verschiedenen chlorierten Verbindungen dargestellt. Eine vollstandige Substitution des Chlors erhalt man mit 1.2 .4.5-[Tetrachlormethyl]-benzol und mitHexa-[p-chlormethyl-phenyll-benzol. Unter den gleichen Bedingungen ergeben sich mit den trimeren und tetrameren cyclischen Phosphornitrilchloriden Nebenreaktionen. Bei der Reaktion mit Hexa-[p-dichlormethyl-phenyll-benzol entsteht ein aus 2 Polystyrolketten gebildetes lineares Polymeres. Die Fraktionierung der Polymeren wird nach der Methode yon BAKER und WILLIAMS in praparativem MaSstab durchgefiihrt. Die Synthesebedingungen, die dabei auftretenden Nebenreaktionen und die Ergebnisse der Fraktionierungen werden diskutiert.

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Section: Analyse Des Conditions De Synth2seunclassified

Synthèse anionique de polystyrènes ramifiés en éatoile à quatre et six branches

Meunier

Leemput

1971

Makromol. Chem.

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“…As a consequence, lessassociated anionic chain ends are assumed, which is also supported by the first-order dependence of the polymerization rate on the active chain-end concentration. 71,72 The solvation of the lithium atom by Lewis bases and the ionization of the carbon−lithium bond also remarkably affect the microstructure of the formed polydiene. 73−77 An increase of the side-chain vinyl regioisomers (3,4-and 1,2-units) at the expense of the 1,4-units was observed, which is explained by an altered charge distribution and stabilization of the propagating anionic chain end.…”

Section: ■ Introductionmentioning

confidence: 99%

Tetrahydrofuran: More than a “Randomizer” in the Living Anionic Copolymerization of Styrene and Isoprene: Kinetics, Microstructures, Morphologies, and Mechanical Properties

et al. 2020

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The statistical anionic copolymerization of isoprene (I) and styrene (S) is commonly used to synthesize tapered block copolymers, enabling control of the phase behavior by adjusting the order–disorder transition temperature, T ODT. Alkyllithium initiation in hydrocarbons is known to afford tapered block copolymers of I and S in one step. The effect of tetrahydrofuran (THF) on the copolymerization kinetics and the resulting copolymers was systematically investigated by increasing the [THF]/[Li] ratio from 0 to 2500 (0 to 29%vol THF). For this purpose, in situ near-infrared (NIR) spectroscopy was employed as a versatile and fast method to track the highly accelerated consumption of the individual monomers. Changes in the I/S comonomer sequence and in the polyisoprene (PI) regioisomers, caused by variation of the THF concentration, were independently determined via NMR and in situ NIR spectroscopy. Reactivity ratios were determined as a function of the [THF]/[Li] ratio. They revealed a gradual reversal from r I ≫ r S over r I ≈ r S to r I ≪ r S. Corresponding changes in the copolymer composition profile up to a complete inversion are evident in thermal properties and morphologies. Although all copolymers possess the same comonomer composition (50%mol = 57%vol polystyrene (PS) units), small-angle X-ray scattering and transmission electron microscopy give evidence of a wide variation in bulk morphologies depending on the gradient profile. Overall, the phase diagram is symmetric, and the succession of phases bears certain similarities to the PI-b-PS case. This is discussed in terms of the increasing incompatibility of PS with 3,4-PI and the more symmetric polymer conformational parameter. The degree of segregation, as well as the nanodomain structure, was found to control the mechanical properties, showing a remarkably different viscoelastic response leading to either hard/brittle or ductile/soft materials. The accessibility of tailored gradient profiles, as well as their in-depth understanding by simply using THF as a microstructural modifier, opens a variety of possible applications. As an example, the synthesis of a PI-selective hydrogenated tapered triblock, possessing a THF-modified, phase-compatibilizing tapered block incorporated in the well-established SIS block architecture, is presented.

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“…We developed these hypotheses because our previous studies confirmed that t-BuP 4 could deprotonate alcohols to form anionic species but could not form free radicals to initiate the polymerization of MMA [25,26]. Moreover, the anionic polymerization of AMA suggested that the anionic species were insufficient to initiate the allyl groups of AMA [27,28].…”

Section: Resultsmentioning

confidence: 85%