Performance function, styrene polymerization control

Investigating the use of functional surfactants for the modification of clay and the properties of the resultant polymer/clay nanocomposite, Hartmann s team [69, 70] used surface-active RAFT agents. The appropriate functionalization of these RAFT agents made their attachment to clay platelets possible. As a result, a controlled growth of polymer chains from the surface of the clay platelets was achievable. They extrapolated to miniemulsion for the first time [71] their studies on styrene polymerization performed in bulk [72] in the presence of Montmorilloniteclay modified with PCDBAB and DCTBAB (Fig. 6). 

Polymeric supports can also be used with advantage to form monofunctional moieties from difunctional (Hies. Leznoff has used this principal in the synthesis of sex attractants on polymer supports (67). Starting from a sheap symmetrical diol he blocked one hydroxyl group by the polymer. Functionalization of cross-linked polymers is mostly performed by chloromethylation (65). A very promising method to introduce functional groups into crosslinked styrene-divinylbenzene copolymers is the direct lithiation with butyllithium in presence of N,N,N, N -tetramethyl-ethylenediamine (TMEDA) (69, 70). Metalation of linear polystyrene with butyl-lithium/TMEDA showed no exchange of benzylic hydrogen and a ratio of attack at m/p-position of 2 1 (71). In the model reaction of cumene with amylsodium, a kinetic control of the reaction path is established. After 3h of treatment with amyl-sodiuni, cumene is metalated 42% in a-, 39% m-, and 19% p-position. After 20h the mixture equilibrates to affort 100% of the thermodynamically more stable a-prod-uct (72). 

The half-sandwich complex, Cp La CFI(SiMe3)2 2(TFIF), showed a dual function of performing the controlled polymerizations of non-polar monomers such as ethylene and styrene as well as polar monomers like MMA, hexylisocyanate, and acrylonitrile in high yields (Scheme 265).971... 

Recently, we report an approach for the preparation of polymer brushes on different kinds of PET surfaces (films, fibers and fabrics). The PET surfaces were first reacted with 1,2-diaminoethane by aminolysis reaction to incorporate functional groups on the surface. Then, in a second step, atom transfer radical polymerization (ATRP) initiators were grafted by reaction with bromoisobutyryl bromide. Surface-initiated ATRP was performed in bulk using styrene monomer and the adequate catalytic system in the presence of sacrificial initiator. Polymer brushes were obtained with a good controlled of polymerization (46). 

A drastic change of nitroxide stmcture was witnessed with the use of the commercially available DBNO (27). In particular, Moad and Rizzardo showed that the dissociation rate constant of a DBNO-based alkoxyamine was higher than any similar alkoxyamines based on cyclic nitroxides bearing tetra-methyl alkyl groups on the vicinity of the aminoxyl function. The first experimental studies were performed by the group of Catala where it was shown that the polymerization of styrene and substituted styrene monomers could be carried out at 90 ° C with all the criteria of control/livingness. However, the polymerization rate was independent of the alkoxyamine concentration and remained governed by the production of thermal radicals in the medium. The tert-butyl-tert-amyl nitroxide 28 was tested by Moad et to control the polymerization of MMA and appeared to be inefficient. 

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