Comb polymer brushes

Fig. 1. a Star polymer, b Comb polymer, c Brush, d Miktoarm star copolymer, e Star copolymer, f Star chain center-adsorbed in a plane, g Dendrimer... 

Going to more complex systems such as aggregates, micelles, polymer brushes or polymers with architectures hke stars, dendrimers, combs, etc. or gels, the scientific arena is wide open for new investigations reveahng new phenomena and new insights. This is even more true for the dynamics of proteins and biomaterials in general, where at present basically only diffusion processes or very local dynamics have been addressed. 

Linear polymer Comb polymer Brush polymer Star polymer... 

Some polymers are linear—a long chain of connected monomers. PE, PVC, Nylon 66, and polymethyl methacrylate (PMMA) are some linear commercial examples found in this book. Branched polymers can be visualized as a linear polymer with side chains of the same polymer attached to the main chain. While the branches may in turn be branched, they do not connect to another polymer chain. The ends of the branches are not connected to anything. Special types of branched polymers include star polymers, comb polymers, brush polymers, dendronized polymers [1], ladders, and dendrimers. A cross-linked polymer, sometimes called a network polymer, is one in which different chains are connected. Essentially the branches are connected to different polymer chains on the ends. These three polymer structures are shown in Figure 1.3. 

ATRP was also combined with other polymerization methods in the preparation of polymer clay nanocomposites. Yang and coworkers reported the preparation of poly(L-lactide) (PLLA) comb polymer brushes on the surface of sihcate layers by using a combination of in-situ ATRP and ROP (Figure 10.7) [34]. An ATRP initiator with a quaternary ammonium salt end group was intercalated into the interlayer spacing of clay layers via ion exchange. In-situ ATRP of hydroxyethyl methacrylate (HEMA) in the presence of CuBr and bipyridine afforded the PHEMA backbone. PLLA comb polymers were grown from the PHEMA backbone by ROP. Because... 

An lUPAC publication (11) discusses both structure-based and source-based representations of comb polymers acomb polymer is described as a macromolecule comprising a main chain with trifunctional points from which linear side chains emanate. If the subchains between the branch points of the main chain and the terminal subchains of the main chain are identical with respect to constitution and degree of polymerization, and the side chains are identical with respect to constitution and degree of polymerization, the macromolecule is termed a regular comb macromolecule. If at least some of the branch points are of functionalities greater than three, the macromolecule may be termed a brush macromolecule. 

Graft poiymer Comb polymer Bottle brush... 

Polymer architecture A polymer s architecture affects many of its physical properties, including viscosity, solubility, glass transition temperature, etc. A variety of techniques may be employed for the synthesis of a polymeric material with a range of architectures, such as star polymers, comb polymers, brush polymers, deudrimers, etc. 

The study of tethered polymer chains is an area which has received increasing attention in recent years. These are systems in which one or both ends of the chain are constrained in their motion because they are attached to a d dimensional surface. This surface could be a point or small central core (d = 0) as in the case of a many-arm star polymer, a line (d = 1) as in the case of a comb polymer, or a flat surface (d = 2) as in the case of a polymer brush. Polymers attached to themselves to form a polymer network or a tethered membrane are also examples of tethered chain systems. An interesting example of a tethered membrane is the spectrin/actin membrane skeleton of the red blood cell skeleton. A schematic illustration of these four examples of tethered chain is shown in Fig. 9.1. Additional interest in tethered chains is due to their technological applications in colloidal stabilization and lubrication. ... 

Polymers attached to a linear backbone form another class of tethered chains, which are intermediate between the stars and brushes. Long-chain comb polymers are branched polymers in which branches of length A are attached to a flexible polymer chain. The branches can either be equally spaced or random. When the branches are long and closely spaced, excluded volume interactions among the tethered side chains can significantly stiffen the central contour. Though such bottlebrush polymers have been synthesized, so far the backbone has been substantially shorter than the side branches. In this case, the structure will not be very different than for a star polymer in which the branches (arms) are attached to a central point. Diblock copolymers in a selective solvent can also form cyhndrical micelles that have similar structures. 

This method would be applicable to various alcohols, while the yield of the dormant species would depend on alcohols. This method would be useful for graft polymerizations from materials with many OH groups, even if not all of the OH groups can initiate. Star and comb polymers and polymer brushes on solid surfaces may easily be obtained without prior attachment of preformed LRP dormant species. 

Freed et al. [42,43], among others [44,45] have performed RG perturbation calculations of conformational properties of star chains. The results are mainly valid for low functionality stars. A general conclusion of these calculations is that the EV dependence of the mean size can be expressed as the contribution of two terms. One of them contains much of the chain length dependence but does not depend on the polymer architecture. The other term changes with different architectures but varies weakly with EV. Kosmas et al. [5] have also performed similar perturbation calculations for combs with branching points of different functionalities (that they denoted as brushes). Ohno and Binder [46] also employed RG calculations to evaluate the form of the bead density and center-to-end distance distribution of stars in the bulk and adsorbed in a surface. These calculations are consistent with their scaling theory [27]. 

The first partially synthetic polymer dates back to 1869, when cellulose (wood pulp) was nitrated (nitrocellulose). The cellulose became ptocessible, and with the further addition of camphor (which acted as a plasticizer), it became a clear, tough, moldable product with the trade name Celluloid. It was widely used at the end of the 19th century in the form of combs, brushes, photographic film, and shirt collars. 

Although the observed undulations are consistent with the scaling picture, it is somewhat in contradiction to the axial contraction. On the other hand, axial contraction in molecular brushes can be limited, first because the backbone segments have limited flexibility and second because of hard core repulsion near the backbone or cylinder axis. In contrast to loose comb-Hke polymers [153], an... 

When the polymeric initiator contains many halogens, there will be many grafted side chains, and the product is called a comb or brush polymer. A variety of polymers can be used as the polymeric initiator, including polymers containing vinyl chloride and 4-chloromethylstyrene units, and halogenated natural and butyl rubbers. Graft copolymers are discussed further in Chaps. 5, 6, and 9. 

The method used to apply and dry a fixative affects the degree of stiffness and hold it imparts to the hairstyle. If applied and then manipulated with a comb, brush, or fingers as the polymer forms its film, the adhesive bonds between the hair are broken, the film coating the hair is broken, and the end result is a soft feel with litde set retention. If the fixative is allowed to dry undisturbed, then the result is a firmer feel and better hold. 

There are many polymer architectures beyond chains such as stars, combs, and brushes. An example of a star-type oligophenylene is structure 100.276 It can be described as possessing three oli-... 

---