Poly controlled anionic

The living nature of the poly(styryl)anion allows one to prepare block copolymers with a great deal of control of the block copolymer structure. The preparation of diblock, triblock, and other types of multiblock copolymers has been reviewed [29-32]. Several of these block copolymers are in commercial use. The basic concept involves first preparing polystyrene block [RSt StLi—see Eq. (2)] and then adding a new monomer that can be added to start another growing segment. 

On the other hand, polytellurides only seem to oxidize metals to the +1 or +11 state. Reaction of equimolar amounts of Te4 with M(CO)6 results in disubstitution of CO forming a cu-complex (CO)4MTe4 (M = Cr (45), W (47)47). If an excess of metal carbonyl is used in the presence of poly-telluride anion, multinuclear products can be isolated and metal-metal bonds can also form, leading to clusters. Careful manipulation of reaction conditions and choice of the polychalcogenide anion used makes possible partial oxidation of the metal centers and cluster formation. The reaction of iron carbonyls with polytelluride anions can lead to a wide array of cluster compounds, the identities of which are controlled by the stoichiometries and compositions of the starting telluride anions. For instance, reaction of [Fe(CO)5] with Te2 leads to the formation of [Fe3(CO)9(ju.3-Te)]2 (48),48 whereas its reaction with increasing amounts... 

Controlled anionic polymerization of alkyl methacrylates initiated by 1,1-diphenyUiexyllithium using a flow microreactor gives the corresponding poly (aUcyl methacrylate)s with high level of control of molecular weight under easily accessible temperatures compared with conventional batch macropolymerization, e.g., —28°C for methyl methacrylate (MMA) (MJMn = 1.16), 0°C for butyl methacrylate (BuMA) MJM = 1.24), and 24°C for tert-butyl methacrylate (f-BuMA) (Mw/Mn = 1.12). Precise control of the reaction temperature and fast mixing of a monomer and an initiator seem to be responsible (Fig. 16) [161]. 

It has been reported that poly(styryl) and poly(isoprenyl) anions underwent efficient functionalization reactions with these terminators in THF or THF/heptane (1/1, v/v) even at -78 °C. The polymers were carefully analyzed by SEC, NMR, end-group titration, and TLC-FID, indicating nearly quantitative end functionalizations (>95%). It was also reported that the resulting functionalized polymers exhibited controlled molecular weights and narrow molecular weight distributions. a,co-Difunctionalized polystyrenes were obtained using a,Q)-dianionic polystyrenes. 

Reetz and co-workers " first used metal-free carbon, nitrogen, or sulfur nudeophiles as initiators for the controlled anionic polymerization of nBA. It was thought that repladng the metal counterion in the polymerization would reduce the problem assodated with aggregation and improve the control over the polymerization. Tetrabutylammonium salts of malo-nate derivatives provided poly(n-butyl acrylate) (PnBA) of rdativdy narrow MWD at room temperature (Scheme 14). Many metal-free initiators for the polymerization of alkyl (meth) acrylates using a variety of anions and cations have been reported (Scheme 15) 208,220-224... 

With appropriately substituted oxetanes, aluminum-based initiators (321) impose a degree of microstmctural control on the substituted polyoxetane stmcture that is not obtainable with a pure cationic system. A polymer having largely the stmcture of poly(3-hydroxyoxetane) has been obtained from an anionic rearrangement polymerisation of glycidol or its trimethylsilyl ether, both oxirane monomers (322). Polymerisation-induced epitaxy can produce ultrathin films of highly oriented POX molecules on, for instance, graphite (323). Theoretical studies on the cationic polymerisation mechanism of oxetanes have been made (324—326). 

Derivatives in the s- and p-Block Elements Supported by Poly(pyrazolyl)borato Ligation Models for Carbonic Anhydrase, Receptors for Anions, and the Study of Controlled Crystallographic Disorder Gerard Parkin... 

ALKYL, HYDRIDE, AND HYDROXIDE DERIVATIVES OF THE s- AND p-BLOCK ELEMENTS SUPPORTED BY POLY(PYRAZOLYL)BORATO LIGATION MODELS FOR CARBONIC ANHYDRASE, RECEPTORS FOR ANIONS, AND THE STUDY OF CONTROLLED CRYSTALLOGRAPHIC DISORDER... 

Figure 17 shows the chemical structures of anionic amphiphile sodium-1,2-bis (tetradecylcarbonyl)ethane-l-sulfonate (2Cj4SNa)[34] and poly(ethyleneimine)(PEI). A benzene/ethanol (9 1)(WV) solution of anionic amphiphile was spread on the pure water surface or the PEI-water solution (lxlO5 unit M in monomer unit, pH=3.2) surface at a subphase temperature, Tsp of 293 K. At this pH, ca. 70 % of nitrogen atom in PEI molecule was protonated[35]. Surface pressure-area(ji-A) isotherms were measured with a microprocessor controlled film balance system. 

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