Homo-poly

Yasuda et al. [122] extended the above work to the block copolymerization of ethylene with lactones. 5-Valerolactone and s-caprolactone were combined with the growing polyethylene end at ambient temperature and the expected AB-type copolymers (100 1 to 100 89) were obtained at high yield. Reversed addition of the monomers (first MMA or lactones and then ethylene) induced no block copolymerization at all, even in the presence of excess ethylene, and only homo-poly(MMA) and homo-poly(lactone) were produced. 

Wiesbrock F, Hoogenboom R, Leenen M et al. (2005) Microwave-assisted synthesis of a 4 X 2-membered library of diblock copoly(2-oxazoline)s and chain-extended homo poly(2-oxazoline)s and their thermal characterization. Macromolecules 38 7957-7966... 

This reaction has the characteristics of a dead end polymerization, and the conversion of monomeric MMA to polymer can be controlled via the azo content of the polystyrene and the reaction temperature. The separation of the reaction products into homopolymer and block copolymer was achieved by selective solvent extraction thus, cyclohexane was used to dissolve the homopolystyrene, acetonitrile the homo-poly-MMA and the copolymer was completely soluble in benzene. The compositition of the crude product as a function of the ratio of MMA/prepolymer is shown in Fig. 4.5 58> ... 

All products were soluble in water, indicating the formation of the graft copolymer and the absence of ungrafted macroinitiator. Dialysis of the product also revealed the absence of low MW (<6000 g mol-1) homo poly(2-methyl-2-oxazoline). Due to the amphiphilic nature of the graft copolymer, aggregation in water as well as in chloroform was shown by NMR spectroscopy, solution vis-... 

In spite of the fact that the method of calculation is somewhat different, the HTH model is very close to the Anderson one. This model may be seen as the reduction of the homo-(poly)nuclear Anderson model to the homo-(bi)nuclear case (A = B). The HTH model also focuses on the two-singly occupied magnetic orbitals in the triplet state [Pg.242]

Using polybutadiene partially hydrolodated led to an even worse efficiency of the secondary Iodide only 10% reacted by addition, the rest by elimination (16) We could produce this way graft copolymers made of a polybutadiene backbone carrying a number of poly-THF grafts but could not avoid the formation of homo-poly-THF. 

This creates a new allyllc chloride that can react the same way with sliver salt producing a carbenlum Ion that undergoes 3 elimination and generates another allyllc chloride group as well as a sequence of conugated double bonds (18) (Figure 4). This process can continue until no allyllc chloride can be formed anymore because of a chain defect. The protons eliminated are the true Initiators for the THF polymerization and this explains why only homo-poly-THF Is formed. 

Varying the feed ratio of the comonomers allowed regulation of the copolymer composition. The isolated yield and M of poly(PDL-co-43 mol % TMC) formed after 24 h (feed 2 1 PDL TMC) was 90% and 30900g/mol, respectively. Thus far, an alternative chemical route to random poly(PDL-co-TMC) is not known. For example, PDL/TMC copolymerizations with chemical catalyst such as stannous octanoate, methylaluminoxane, and aluminum triisoproxide resulted either in homo-poly(TMC) or block copolymers of poly(TMC-co-PDL) [114]. Chemical... 

Furuhashi Y, Imamura Y, Jikihara Y, Yamane H (2004) Higher order structures and mechtmical properties of bacterial homo poly(3-hydroxybutyrate) fibers prepared by cold-drawing and annealing processes. Polymer 45 5703-5712... 

Yamamoto T, Kimizu M, Kikutani T, FirruhasM Y, Cakmak M (1997) The effect of drawing and annealing conditions on the structure and properties of bacterial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) fibers. Int Polym Process XII 29-37 Yamrme H, Terao K, Hiki S, Kimirra Y (2001) Mechanical properties and higher order structure of bacterial homo poly(3-hydroxybutyrate) melt spun fibers. Polymer 42 3241-3248... 

The high activity of M(L )2 + L (L = crown-ethers or ammonium quaternary salts) as catalysts of the ethylbenzene oxidation into a-phenylethylhydroperoxide is connected with the formation active primary complexes (M(II)(L )2), (L ), and homo poly nuclear hetero ligand complexes M(II) (L )y(L ) L j, ( A (Ni), B (Fe)) (formed through dioxygenase-like mechanisms). The stability of A ( B ) to the L dioxygenation seems to be due to the intramolecular and intermolecular H-bonding interactions. 

Figure 1. Gel permeation Chromatograph of homo-poly(myrcene) poly(myrcene-b-styrene)...

The absence of transfer reactions is confirmed by the possibility to produce block-copolymers of tert.butylaziridine by using "living" cationic poljrmers as initiator. This has been achieved with living poly(tetrahydrofurane) at 0 C (O and with living polystyrene perchlorate, at -60 C (7 ). In both cases the formation of block-copolymers was demonstrated by the solubility properties of the obtained polymers which were different from those of homo poly-(tert.butylaziridine), and by gel permeation chromatography. 

Due to sulfonic acid group in 2-acrylamido-2-methylpropanesulfonic acid (AMPS) molecules, homo-poly(AMPS), or (AMPS)-based co-polymers (Fig. 13.13) would be applicable to proton-conductive membranes for fuel cell applications [61]. The amphiphilic monomer can be easily polymerized with radical initiators and the price... 

It is important to discuss this reaction which is more or less a transposition to solid state chemistry of mechanisms which are known to occur in solution, for example in the process of formation of hetero- or homo poly ions. 

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