Comblike polymers

Figure 4 Temperature dependence of ionic conductivity for comblike polymers 3 and 4 in...

N. A. Plate, V. P. Shibaev in Grebneobraznye polimeri i zhidkie Kristally (Comblike Polymers and Liquid crystals), Khimiya, Moscow, 1980... 

Thus, the remoteness of mesogenic groups from the backbone provided by a polymethylene spacer secures them sufficient autonomy from the main chain. On the other hand, the fact that mesogenic groups are chemically linked with the main chain of the macromolecule assists their cooperative interaction. This is why comblike polymers have come to be accepted as convenient matrices for constructing LC polymers. Already a few hundred liquid-crystalline polymers with various mesogenic side groups have been synthesized. 

Polymerization of these monomers is commonly achieved by radical polymerization in solution and/or in bulk. Poly(monoitaconate)s may be considered as typical comblike-polymers depending on the length of the side chain in the case of aliphatic derivatives [191,192],... 

A macromonomer is a macromolecule with a reactive end group that can be homopolymerized or copolymerized with a small monomer by cationic, anionic, free-radical, or coordination polymerization (macromonomers for step-growth polymerization will not be considered here). The resulting species may be a star-like polymer (homopolymerization of the macromonomer), a comblike polymer (copolymerization with the same monomer), or a graft polymer (copolymerization with a different monomer) in which the branches are the macromonomer chains. 

A HE SEARCH FOR PLASTIC, solvent-free electrolytes for use in solid-state batteries is being actively pursued in several laboratories (1-4). A number of reports have stressed the need for facile motion of the macromolecular chain in order to promote the ion conduction process in the polymer matrix, because this process occurs primarily via a free-volume mechanism (1-4). Comblike polymers with oligooxyethylene side chains constitute effective media for ion conduction of solubilized alkali salts (5-8). The low glass transition temperature (Tg) of poly(dimethylsiloxane) suggests that polysi-loxane could serve as a suitable backbone for such a comb polymer, and recent studies (9-J2) indicate this to be the case indeed. 

Loos, K. Munoz Guerra, S. Supramolecular Polymers-Chapter 7 Microstructure and Crystallization of Rigid-Coil Comblike Polymers and Block Copolymers, Marcel Dekker New York, 2000. 

Loos K, Munoz-Guerra S (2000) Microstructure and crystallization of rigid-coil comblike polymers and block copolymers. In Ciferri A (ed) Supramolecular polymers, Chap 7. Dekker, New York... 

Polyolefin blends always show a raised swell of the extrudate jet in comparison with homopolymers (83). This was shown earlier (88) for LDPE/LLDPE blends. Some researchers reported (89,90) a significant influence of the molecular structure on properties of the polymer melts the polymers whose chains contain starlike branches show increased sensitivity toward shear stresses applied onto their melts. The presence of comblike segments increases the melt strength. For example, the addition to LLDPE up to 10 wt% of a comblike polymer (copolymer of a polyethylene macromonomer, k. 8000gmol , and ethylene and hexene) allows raising the strength of polymer melt almost by one decimal order (86). The MFl of the blend varies less substantially. The melt strength of LLDPE blends can be... 

Table Main Characteristics of LC CN-containing Comblike Polymers. 

No.25, 12th Dec.2000, p.9228-32 COMBLIKE POLYMERS WITH OCTADECYL SIDE CHAIN AND CARBOXYL FUNCTIONAL SITES SCOPE FOR EFFICIENT USE IN MINIEMULSION POLYMERIZATION Baskar G Landfester K Antonietti M Max-Planck-Institut fuer Kolloid- Grenzflaech. 

Figm 5 Comblike polymer local structure (a) and coarse-grained model (b). 

On the (local) length scale on the order of D, the comblike polymer with densely grafted side chains can be considered as a cylindrical polymer bmsh, that is, an array of polymer chains end grafted with an axial separation to a thin cylinder. This local cylindrical symmetry is ensured by either the intrinsic backbone rigidity or, in the case of flexible backbone, by repulsive interactions between the grafts. This repulsion induces axial tension in the backbone, which maintains locally cylindrical configuration of the comblike polymer in spite of short-scale bending fluctuations in the extended flexible backbone. 

The local conformational properties of the comblike polymer with flexible backbone are summarized in Table 3, which indicates that both grafts and spacers are extended with respect to chararteristic dimensions... 

Table 3 Local conformational properties of densely grafted n/m s> 1) comblike polymer with flexible backbone in dilute solution...

Making use of eqn [77] and Table 3, the following scaling dependences for the overall dimensions of the long comblike polymer can be derived ... 

As follows from eqn [78], the intramolecular repulsions of the grafts lead to significant increase in the overall size of the comblike polymer as compared to that of the bare backbone Remarkably, using a simplified mean-field Flory approach, that is, balancing the average intramolecular excluded-volume repulsions, FinJk T=x(Mnlm) IR with the conformational entropy of the extended main chain. 

Microstructure and Crystallization of Rigid-Coil Comblike Polymers and Block Copolymers... 

Figure 25 Three-dimensional assemblies reversible transitions for comblike polymer Pa AA-18. The aliphatic segments interdigitate loosely in the liquid-crystalline phase dXT < T < T2 forming supramolecular clusters. (From F. Lopez-Carrasquero, S. Monserrat, A. Martinez de Harduya, and S. Muhoz-Guerra. Macromolecules 28 5535, 1995. Copyright 1995 ACS.)...

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