New Sequential Copolymers and Networks by a Combination of Techniques

Abstract

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.

Micellization of block copolymers

“…CMC and particle size were found in the same range as for the corresponding PS -PEO copolymers. PIB -PEO block copolymers micelles studied by Kennedy [179] should finally be mentioned as the PIB hydrophobic block of very low T g could favorize the unimer -micelle equilibrium.…”