Carbocationic polymerizations

Living carbocationic polymerization (LCCP) (Faust and Kennedy, 1987 Ivan and Kennedy, 1990 Joseph, 1999) relies on complex ion equilibria, which are normally maintained in the absence of polar solvents and monomers. Only specific polar additives (such as di-tert. butyl pyridine, or N,N-dimethyl acetamide) are compatible with a LCCP, so that the direct copolymerization of monomer containing H bonds is not possible. In the same manner, endquenching reactions with quenchers containing H bonds is not possible, as often only chlorine-telechelic polymers would result. 

Synthesis and Self-Assembly nf Hv ogen-Bonded SupramolecularPol  

Indeed, this for the first time opens the possibility to introduce specific polar monomers during a LCCR 

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G-5 Aliphatic Petroleum Resins. Carbocationic polymerization of C-5 feedstreams has been accomptished with various Friedel-Crafts catalyst systems. Table 3 compares the efficiencies of selected Lewis acids ia the polymerization of a typical C-5 stream containing 43 wt % C-5—C-6 diolefias and 47 wt % C-5—C-6 olefins (20). Based on weight percent yield of resia at equimolar coaceatratioas of catalyst (5.62 mmol/100 g), efficieacy follows AICI3 AlBr3 > BF3etherate-H20 > TiCfy > SnCl. The most commonly used catalyst in petroleum resin synthesis is AlCl. ... 

Hydrocarbon resins based on CPD are used heavily in the adhesive and road marking industries derivatives of these resins are used in the production of printing inks. These resins may be produced catalyticaHy using typical carbocationic polymerization techniques, but the large majority of these resins are synthesized under thermal polymerization conditions. The rate constants for the Diels-Alder based dimerization of CPD to DCPD are weU known (49). The abiHty to polymerize without Lewis acid catalysis reduces the amount of aluminous water or other catalyst effluents/emissions that must be addressed from an environmental standpoint. Both thermal and catalyticaHy polymerized DCPD/CPD-based resins contain a high degree of unsaturation. Therefore, many of these resins are hydrogenated for certain appHcations. 

J. P. Kennedy and E. Marechal, Carbocationic Polymerization, Wiley Interscience Publishers, John Wiley Sons, New York (1982). 

F. Model Experiments on the Stability of Si-H Bonds in Carbocationic Polymerization... 

Evidently the Si-H bond is stable toward Me3Al under conditions similar to these prevailing during a carbocationic polymerization. 

Kennedy JP, Marechal E (1982) Carbocationic Polymerization. J. Wiley Sons, New York, p 411... 

Though living anionic polymerization is the most widely used technique for synthesizing many commercially available TPEs based on styrenic block copolymers, living carbocationic polymerization has also been developed in recent years for such purposes [10,11], Polyisobutylene (PlB)-based TPEs, one of the most recently developed classes, are synthesized by living carbocationic polymerization with sequential monomer addition and consists of two basic steps [10] as follows ... 

Section 7.3 will describe tools we developed to synthesize and characterize soft dendritic nanostructured TPE biomaterials via living carbocationic polymerization, and decorate their surfaces with tissue-friendly groups. 

Our discovery that epoxides can initiate carbocationic polymerization led to the effective direct functionalization of PIBs with hydroxyl groups. Figure 7.18 shows our novel method of direct surface functionalization of SDIBSs using 4-(l,2-oxirane-isopropyl)-styrene, a new inimer. 

Puskas, J.E., Antony, P., Paulo, C., Kwon, J., Kovar, M., Norton, P., and Altstadt, V. Macromolecular engineering via carbocationic polymerization Branched and hyperbranched stmctures, block copolymers and nanostructures, Macromol. Mater. Eng., 286, 565-582, 2001. 

Michel, A., Brister, L.B., and Fhiskas, J.E. Novel epoxide initiators for carbocationic polymerizations, NATO ASI Ionic Polymerizations and Related Processes, NATO Science Series 359, Kluwer, Dordrecht, the Netherlands, 1999. 

Synthesis of PIB prepolymers. fm-Chlorine-telechelic PIB (Mn=4,000 MVf/Mn 1.09) (7), and an allyl-telechelic PIB (Mn=9,500 Mw/Mn 1.14) (7,8) were prepared by living carbocationic polymerizations. The tert-chlorine ended PIB was quantitatively dehydrochlorinated (9) to -C(CH3)=CH2 terminated polymer. Both olefin-telechelic PIBs were then hydroborated and oxidized (10) to prepare the primary hydroxyl termini. The hydroxyl-telechelic polymers were esterified with methacryloyl chloride to methacrylate-telechelic PIBs, MA-PIB-MA (11). 

Kennedy, J. P. Marechal, E. Carbocationic Polymerization. (1982) John Wiley and Sons, Inc. New York. 

Quasi-living Carbocationic Polymerization of Alkyl Vinyl Ethers and Block Copolymer Synthesis... 

Living" carbocationic polymerizations are most difficult to achieve mainly because of chain transfer to monomer and termination processes both of which frequently occur in carbocationic polymerizations. It has recently been demonstrated (JL) that "quasiliving" polymerization of a-methylstyrene (aMeSt) can be achieved by slow and continuous monomer addition and that the number-average molecular weight (Mn) of PaMeSt increases linearly with the weight of added monomer. A theory for quasiliving polymerizations has been developed (2). 

Majoros, I., Nagy, A. and Kennedy,. P. Conventional and Living Carbocationic Polymerizations United. I. A Comprehensive Model and New Diagnostic Method to Probe the Mechanism of Homopolymerizations. Vol. 112, pp. 1-113. 

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