New Telechelic Polymers and Sequential Copolymers by Polyfunctional Initiator-Transfer Agents (Inifers)

1985

Polym J

ABSTRACT:Research into the mechanism of the inifer process led to perfectly endfunctionalized (telechelic) linear or three-arm star polyisobutylenes (PIB)s. Recently a semicontinuous technique has been developed and is now routinely employed for the synthesis of these materials. The ingredients are fed into a stirred reactor and by controlling their input rates PIB telechelics with virtually theoretical M. and Mw! M. are harvested. The first intermediates that form are !-chlorine telechelic PIBs which can then be quantitatively converted to other well-defined telechelics, e.g., PIBs carrying olefin, alcohol, phenol, etc. end groups. PIB diols and triols are now available on a semicommercial scale in various molecular weights. Telechelic PIBs have been used for the preparation of new block copolymers and/or networks by a variety of techniques. For example, a combination of polymerization and coupling techniques have been employed for the synthesis of a new class of di-and triblock copolymers consisting of PIB and polyethylene glycol sequences. Thus phenol-ended PIBs were reacted with a slight stoichiometric excess of diisocyanates, and the resulting isocyanate-capped prepolymers were then reacted with commercially available polyethylene glycols. These hydrophobic/hydrophilic (amphiphilic) materials exhibit some unusual dilute solution properties.

mentioning

confidence: 64%

“…The compositions of the final charges in the semicontinuous and batch runs were identical. Further experimental details are given in ref 9.…”

Section: Methodsmentioning

confidence: 99%

Section: Semicontinuous Inifer Systemsmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

New Sequential Copolymers and Networks by a Combination of Techniques

1985

Polym J

Electrophilic substitution of organosilicon compounds. II. Synthesis of allyl‐terminated polyisobutylenes by quantitative allylation of tert‐chloro‐polyisobutylenes with allyltrimethylsilane

Wilczek

J. Polym. Sci. A Polym. Chem.

1987

SynopsisEssentially quantitative allylation of linear and threeam star tert-chloro capped polyisobutylenea [%I-PIB-Cl' and PIB(Cl'),] has been achieved by the use of allyltrimethylsilane (AllylSiMe3) and Friedel-Crafts acids. Quantitative allylation occurs under suitable conditions, e.g., slight molar a c e s of "XI, and AllylSiMe,, polar media, -70°C. These conditions have been developed from quantitative model allylation experiments using 2,4,4-trimethyl-2-chloropentane. Essentially quantitative allylation occurs with long-chain or "once fired" tert-chloro-end groups. Complete allylation can also be effected in a "one-pot two-step" synthesis, i.e., by first preparing the tert-chlorc-ended PIB by the inifer method and without isolating the product, completing the s y n t h b by allylation in the same reactor. Extensive but not quantitative allylation can also be obtained in sihr, i.e., during polymerization, by the use of the AllylSiMe3/cumyl chloride/BC13/isobutylene combination. While allylation proceeds with great ease under the mildest conditions, e.g., -7OoC, vinylation with vinyltrimethylsilane could not be achieved even under more forcing conditions.

Polyisobutylene‐based polyurethanes with unprecedented properties and how they came about

Kang

Erdődi

J. Polym. Sci. A Polym. Chem.

2011

Self Cite

This highlight concerns the birth, development, and present status of unique polyurethanes consisting of polyisobutylene soft segments and conventional hard segments (PIBbased PUs) exhibiting unprecedented combinations of mechanical properties and oxidative/hydrolytic/biological stability. Impetus for developments was to improve the rather poor chemical resistance of conventional polyurethanes by replacing their soft segments with polyisobutylene segments. Research started in the 1980s with the synthesis of a,x-polyisobutylene diols (HO-PIB-OH) by the inifer technique and preparation of PIB-based PUs, which indeed exhibited outstanding stabilities, however, had poor mechanical properties. Because of cumbersome early techniques and expensive reagents, worldwide research and industrial interest waned and developments went into hibernation. Recent discoveries, including living isobutylene polymerization, improved end-functionalizations, inexpensive ingredients, and new insight into PU morphology, lead to simple and less expensive synthesis strategies and, consequently, to resumption of fundamental and applied research. Presently, we can produce kilogram quantities of polyurethanes and polyureas with unprecedented combinations of excellent physical-mechanical-environmental-biological and processing properties. This highlight focuses on facts and insights, which occurred since the discovery and shaped developments. These events are worth reviewing and analyzing because they illustrate how contemporary academic research is driven by curiosity (fun) and economic considerations (money).