Macromonomer Synthesis Using Cationic Polymerization

Most of the reported polyfvinyl ether) macromonomers have been prepared with a methacrylate end group which can be radically polymerized and which is non-reactive under cationic polymerization conditions [71-73]. Generally, the synthesis was based on the use of the functional initiator 30, which contains a methacrylate ester group and a function able to initiate the cationic polymerization of vinyl ethers. Such initiator can be obtained by the reaction of HI and the corresponding vinyl ether. With initiator 30 the polymerization of ethyl vinyl ether (EVE) was performed using I2 as an activator in toluene at -40 °C. The MW increased in direct proportion with conversion, and narrow MWD (Mw/Mn= 1.05-1.15) was obtained. The chain length could be controlled by the monomer to initiator feed ratio. Three poly(EVE) macromonomers of different length were prepared by this method Mn=1200,5400, and 9700 g mol-1. After complete... 

A class of end-functionalized polymers with polymerizable terminal groups are generally called macromonomers. By both functional initiator and terminator methods, a variety of macromonomers have been synthesized in living cationic polymerization of vinyl ethers, styrenes, and isobutene, as summarized in Table 3 [16,31,147,149-151,155,158-171]. Some of these macromonomers are used in the synthesis of graft polymers (Section VI.C). 

Cationic polymerization has also been used for the synthesis of macromonomers, especially after the development of living cationic polymerization techniques (73). Macromonomers were prepared by the cationic ringopening poljnnerization of tetrahydrofuran (THF) using methyltriflnoromethane sulfonate, followed by termination with 3-sodio-propyloxydimethylvinylsilane to give a macromonomer with vinyl silane end groups (74) (eq. 18). 

In analogy to anionic polymerization, both initiating and end-capping methods are used to obtain macromonomers via cationic polymerization. However, termination is only quantitative in the case of ring-opening polymerizations. Table 5 presents some representative methods which have been reported for the synthesis of macromonomers from PTHF. Scheme 14 shows a typical reaction scheme in which the end group is introduced using a functionalized initiator. ... 

PIB-toughened poly(methyl methacrylate) (PMMA) networks have been reported in which the PIB domains are covalently bound to a PMMA matrix [26]. The synthesis involved a macromonomer approach where a combination of radical and cationic polymerization techniques were used. Methacrylate tri-telechelic PIBs were prepared by living cationic polymerization followed by end functionalization and used in free-radical solution copol)mierization with various amounts of MMA. Scheme 14 represents the general reaction pathways for the synthesis of network. 

Techniques derived from anionic or cationic living polymerization methods have widely been used. They are efficient because of the long lifetime of the active sites. Once polymerization is completed these sites are used for functionalization purposes. Alternately, unsaturated ionic initiators have been used but to a lesser extent because of the requirement involved that the polymerizable groups remain unscathed during the macromonomer formation. The versatile inifer method has also been applied to the synthesis of macromonomers. 

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