Block copolymers norbomene

Amphiphilic star-block copolymers can be prepared by adding a polycyclic diene such as 238 to a living diblock copolymer made by sequential ROMP of (i) the monomer in Table 9 with R = COOSiMe3, and (ii) norbomene. The trimethylsilyl ester groups are then converted to carboxylic acids by soaking the cast film of the polymer in water for 2-3 days to give a product with a hydrophobic core of polynorbomene and a hydrophilic outer layer126,502. 

A titanacyclobutane carrier for the living ROMP of norbomene can be converted, by reaction with methanol, into an alkyl titanocene methoxide complex which can then be used in conjunction with EtAlCl2 to propagate the ZNP of ethene, so forming a block copolymer of norbomene and ethene620. 

Scheme 24 Synthesis of random and block copolymers via ROMP of amino acid-functionalized norbomenes [173]...

Amino acid-based norbomene random and block copolymers have been synthesized by Sanda, Masuda et al. [178]. The blocks were constructed with monomers containing either the ester or carboxyl amino acid forms, and C4 was used. While the random copolymers were partially soluble in acetone, the block copolymers were soluble through formation of reverse micelles (Scheme 24). Moreover, the diameter of these aggregates was around 100 nm as measured by DLS and AFM. Amino acid-based ROMP monomers with a different cyclic core, i.e., cyclobutenecarbonyl glycine methyl esters, were polymerized by Sampson et al., leading to head-to-tail-ordered polymers without stereocenters [179]. C6 was used and polydispersities between 1.2 and 1.6 were obtained. 

The living ROMP reactions of norbomene and norbomene derivatives have been used to make a variety of polymers possessing unusual properties. Copolymerization of selected fimctionalized norbomenes with norbomene has been used to synthesize star polymers and side-chain liquid crystal polymers. This chemistry has also resulted in the preparation of phase separated block copolymers that contain uniform sized metal or semiconductor nanoparticles. The... 

Photopolymerization with transition metals [121] has been used for the formation of homopolymers and block copolymers from norbomene (nbn) and phenylacety-lene with W(CO)e (eq. (18) cf. Sections 2.3.3 and 3.3.10.1) [122]. 

Macromolecular initiators have also been applied successfully. The left column of Table VI represents several examples of such initiators. Poly(tetrahydrofuran) and poly(norbomene) were used as macroinitiators for ATRP to m block copolymers. 

When the propagating species are long-lived, it is possible to make block copolymers of controlled chain length by sequential addition of monomers, for example, with ClC=CC4H9/ClC=CCi4H29 and with acetylene/norbomene (see Tables 10.6 and 10.7). 

Norbomenes with 5-substituents containing various metallic elements have been prepared and polymerized. The polymers containing tin have biocidal properties (Streck 1982, Lequan 1984). Block copolymers containing lead, palladium, platinum and other metals are described in Ch. 14. 

Table 14.1 Block copolymers made from norbomene (Mi) by sequential addition of monomers... 

Amphiphilic star-block copolymers can be readily prepared by the use of a suitable polycyclic diene such as 4 or the more readily available 5. For example, monomer 6 is first added to the initiator Mo-2 (Table 14.1), followed by norbomene... 

The development of novel titanium carbene complexes by Grubbs has opened up a route to living polymer systems, using coordinating polymerizations as opposed to those derived from ionic initiators, which can be used to form block copolymers or produce chains with a functionalized end group. The initiating species are formed by the reaction of norbomene with a titanocyclobutane derived from 3,3-dimethyl cycloprene... 

ROMP provided the first examples of block copolymers with pendant metal-containing groups. As discussed earlier, ROMP of substituted norbomenes has been used to prepare block copolymers with ferrocene side groups (see Section 2.2.1.2). 

Orientations in elongated mbbers are sometimes regular to the extent that there is local crystallization of individual chain segments (e.g., in natural rubber). X-ray diffraction patterns of such samples are very similar to those obtained from stretched fibers. The following synthetic polymers are of technical relevance as mbbers poly(acrylic ester)s, polybutadienes, polyisoprenes, polychloroprenes, butadiene/styrene copolymers, styrene/butadiene/styrene tri-block-copolymers (also hydrogenated), butadiene/acrylonitrile copolymers (also hydrogenated), ethylene/propylene co- and terpolymers (with non-conjugated dienes (e.g., ethylidene norbomene)), ethylene/vinyl acetate copolymers, ethyl-ene/methacrylic acid copolymers (ionomers), polyisobutylene (and copolymers with isoprene), chlorinated polyethylenes, chlorosulfonated polyethylenes, polyurethanes, silicones, poly(fluoro alkylene)s, poly(alkylene sulfide)s. 

Using the more successful arm-first approach, in-chain functionalized stars were prepared. 2,3-Dicarbomethoxynor-bomadiene was polymerized with the same catalytic systems followed by the addition of the difunctional monomer, leading to the desired functionalized star polymers. SEC revealed the presence of 10-20% unreacted homopolymers. Using the same procedure, star-block copolymers can also be prepared. 2,3-Dicarbomethoxynorbomadiene was initially polymerized followed by the addition of norbomene for the synthesis of the living diblock copolymers. Reaction of these living diblocks with the difiinctional monomer afforded the star-block copolymers with complete consumption of the living arms (Scheme 56). 

Another difiinctional monomer, endo-cis-endo-hexacydo-[10.2.l.l .l .0 .0 ]heptadeca-6,13-diene was also used for the synthesis of star polymers. Using the arm-first approach, star polymers of norbomene, 5,6-bis (methox3methyl)norbomene (DMNBE) and 5,6-bis(dicarbotri-methylsilyloxy) norbomene (TMSNBE) were obtained. Amphiphilic star-block copolymers were prepared by reacting... 

ROMP is a chain growth polymerization that converts cydic olefins to a polymeric material in the presence of transition metal-based complexes such as Ti, Mo, W, Ta, Re, and Ru complexes (Scheme 54) 12,329-337 powerful polymerization method is broadly applicable for the preparation of well-defined polymers. Therefore, transformation reactions of both polycydic olefins such as norbomene (NB), norbona-diene, and dicyclopentadiene and low-strain cydic olefins induding cydopentene (CP) and cydoheptene allow extension of the range of attainable block copolymers. 

Matron and Grubbs formed block copolymers by combining ring opening metathesis polymerization with ATRP [437]. Use was made of fast initiating ruthenium metathesis catalyst to form three different monotelechelic poly(oxa)norbomenes. The ends were functionized and ATRP polymerizations of styrene and ferf-butyl acrylate followed. 

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