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Backbone diblock polymer

Random copolymers have no pattern to the sequence of monomers. A random copolymer using repeat units A and B would be called poly(A-co-B). The term alternating copolymer is fairly self-explanatory with an alternating pattern of repeat units. Block copolymers consist of long-chain segments (blocks) of single-repeat units attached to each other. Block polymers most commonly employ two different repeat units and contain two or three blocks. Block copolymers are named poly(A-f B) or simply AB for polymers with two blocks (diblock polymer). A triblock copolymer would be named poly(A-b-B-b-A) or simply ABA. Grt0 copolymers consist of a backbone with side chains of a different repeat unit and are named poly(A-g-B). (See Fig. 11.6.)... [Pg.264]

Polyacetylene appeared to be insoluble in all solvents tested [10,32]. Note, however, that units of polyacetylene in soluble form have been obtained by using graft or block copolymerisation methods, such as grafting polyacetylene to soluble polymers [33-37], grafting soluble polymeric chains on the main backbone of polyacetylene [38] and diblock copolymerisation [39-42]. In contrast to polyacetylene, polymers that can be obtained from substituted acetylenes are soluble in common solvents. [Pg.381]

Brushes with diblock side chains have been prepared by the same concept as illustrated in Figure 13. In this case either a polystyrene block or a poly-(n-butylacrylate) block was grafted first by atom transfer polymerization, ATRP, on a poly(2-bro-mopropanoyl ethyl methacrylate), pBPEM, on which in a second step the other monomer was polymerized as the second block.189 Table 4 summarizes the molecular structure of the corresponding polymers, i.e., (i) the macroinitiator or mere backbone molecule (pPBEM) from which (ii) a brush with pnBuA homopolymer side chains (pBPEM-g—pnBuA), (iii) a... [Pg.380]

Starved-feed emulsion polymerization can be conducted without emulsifiers if suitable comonomers and procedures are utilized.341 Polymerization of a water-soluble methacrylate like HEMA in the presence of a CCT agent is carried out initially. The resulting HEMA oligomer is further copolymerized with hydrophobic monomers so that the resulting diblock copolymer serves as a surfactant (see, for instance, sections 5.3 and 5.4). During the cross-linking process, all of this surfactant is incorporated into the polymer backbone and is thus immobilized, overcoming the problem of residual surfactant in the final product. [Pg.541]

Another pyrrolidone-based phosphine has been incorporated into amphiphilic, water-soluble diblock co-polymers based on 2-oxazalone derivatives (Scheme 61). The synthesis involved the initial preparation of a diblock co-polymer precursor with ester functionalities in the side chain. This was achieved by sequential polymerization of 2-methyl-2-oxazoline to form the hydrophilic block that provides water solubility, and subsequently a mixture of ester-functionalized oxazoline 147 and 2-nonyl-2-oxazoline, the latter increasing the hydrophobicity of the second polymer block. Having made the backbone, the ester functionalities were converted into carboxylic acids giving polymer 148, which was then reacted with the phosphine ligand to give the desired supported material, 149. This was used in asymmetric hydrogenation reactions with success. [Pg.710]

Living ring opening metathesis polymerization methods (ROMP) were first employed to synthesize LC-coil diblock copolymers by Komiya and Shrock [80] in 1993. The structure of their polymer system is shown in Scheme 7D. Recent work from Grubbs group also used a novel ruthenium catalyst which can tolerate more functional groups [81] to synthesize well-defined LC-coil block copolymers [82]. The ROMP polymer backbone can be hydrogenated to create saturated structure to improve its stability. [Pg.78]

In the spirit of the discussion so far, an amorphous/smectic LC diblock can be considered to be an A(CB) triblock copolymer, where A denotes the amorphous polymer and C and B the backbone and mesogens of the smectic polymer, respectively (Fig. lb). If Tai Tqdt. the Sm-A phase forms within a well microphase-separated block system and one woifld expect XBC XAC> XAB- Only when this condition is fulfilled the usual description as a diblock system is effectively correct. However, a different situation arises if the backbone in the smectic polymer is similar to the polymer in the amorphous block C = A A. Now little incompatibility exists between the polymer in the amorphous block and the backbone of the smectic LC block. In that situation xac 0, and xbc Xab 5 > 0. A correct description of this situation would be A(A B), and the interplay between the smectic ordering and the microphase separation is expected to become more important. [Pg.76]

Block Type The preparation of molecular brushes with block copolymer backbones has been reported [39, 58, 90, 110-112]. These examples are mostly brush-coil block copolymers, in which one block is a cylindrical brush while the other is composed of a Hnear polymer chain. As an example, comonomers of octadecyl methacrylate (ODMA) and TMS-HEMA were polymerized sequentially via ATRP to afford a PODMA-b-P(TMS-HEMA) (PODMA = poly(octadecyl methacrylate)) diblock copolymer main chain. The poly(HEMA-TMS) block was converted into PBIEM polyinitiator, which was used for the polymerization of nBA this formed a PnBA block brush with a PODMA coil at the end of the main chain [28]. Owing to the crystalline nature of the PODMA segments, the self-assembly of the brush-coil block molecular bmshes was observed using AFM. This type of material gives rise to a new class of supersoft thermoplastic elastomers [95,113]. [Pg.284]

From a stmctural point of view, assembled polymer cylinders are naturally of 100% grafting density. Each polymer chain that is either crosslinked or fixed in the backbone domain possesses a corresponding block that stretches out of the core as a side chain this is because they are from an identical diblock copolymer molecule, and so wiU always be covalently bonded. [Pg.296]


See other pages where Backbone diblock polymer is mentioned: [Pg.198]    [Pg.932]    [Pg.207]    [Pg.184]    [Pg.480]    [Pg.447]    [Pg.149]    [Pg.158]    [Pg.8]    [Pg.104]    [Pg.158]    [Pg.352]    [Pg.106]    [Pg.142]    [Pg.9]    [Pg.52]    [Pg.496]    [Pg.266]    [Pg.8]    [Pg.380]    [Pg.48]    [Pg.516]    [Pg.348]    [Pg.146]    [Pg.300]    [Pg.74]    [Pg.82]    [Pg.107]    [Pg.428]    [Pg.44]    [Pg.106]    [Pg.286]    [Pg.288]    [Pg.294]    [Pg.610]    [Pg.1108]    [Pg.1149]    [Pg.217]    [Pg.224]    [Pg.237]    [Pg.257]   
See also in sourсe #XX -- [ Pg.198 ]




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Polymer backbone

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