Poly macromolecules

Remarkable concentration of the photon energy absorbed by aromatic dendritic scaffold toward the focal point (herein called antenna effects ) is one of the most distinct features of the dendritic macromolecules. Poly(benzyl ether) (PBE) dendron [1] has been studied most extensively as an efficient antenna dendron. Careful studies have revealed the crucial role of the symmetric dendritic structure for the antenna effect. 

Rzaev, Z. M. et al. VIIth IUPAC Microsymp. on Macromolecules. Poly(vinyl chloride), its Formation and Properties, Abstr., p. Bl, Prague 1970... 

Synthetic Macromolecules poly(sulfone-co-amine) H branch 361 212... 

Impressive progress has been made in stereospecific polymerization of cyclic ethers and cyclic esters since the first edition of CPS was published. A novel ROP phenomenon called stereocomplexation, which is especially important when it involves homochiral macromolecules, poly(R)- and poly(S)- polylactides, is analyzed in detail (chapter devoted to cyclic esters). A breakthrough in the stereoregulation of methyloxirane (propylene oxide) polymerization is the subject of a chapter on stereospecific polymerization of oxiranes. 

The formation of supramolecular liquid crystalline order was recently reported in suspensions of (extended-chain) crystalline whiskers of the flexible macromolecule poly(tetrafluoroethylene) (PTFE) (22). This finding will be briefly reviewed, because it once more illustrates that spontaneous ordering is not the exclusive property of solutions or melts of (semi) rigid molecules. Flexible macromolecules, when assembled into asymmetric objects, such as extended-chain whiskers, also may exhibit the fascinating and useful selfalignment phenomenon that leads to liquid crystalline order. It is believed that this class of soft condensed matter will provide new avenues for processing (flexible) macromolecules into highly ordered materials with anticipated superior performance. 

The kinetics of oxidation of a macromolecule, poly(ethylene glycol) [PEG] by ceric sulfate in sulfuric acid medium has been studied by means of UV-visible spectrophotometry. The observed difference in rates of oxidation has been explained in terms of cage formation. The oxidation of PEG proceeded without the formation of a stable intermediate complex. The order with respect to the concentrations of PEG and ceric sulfate has been found to be one and the overall order is two. The effects of acid concentration, sulfate ion concentration, ionic strength and temperature on the rate of the oxidation reaction have been studied. The thermodynamic parameters for the oxidation reaction have also been presented. Based on the experimental results, a suitable kinetic expression and a plausible mechanism have been proposed for the oxidation reaction. 

Fig. 50 Structures of PEGylated polybenzoMvene brushes (PPBBs). For the sake of clarity, the structural moieties used to define the polymer names are colored differently. MOEG-9 side chains are reported in red, while triazolomethyl spacer is shown in blue. Finally, polybenzofulvene backbones of the parent macromolecules poly-BFl and p>oly-BF3k are depicted in black...

Fig. XV-1. Plots of t/CRT vs. C for a fractionated poly(methyl acrylate) polymer at the indicated temperatures in degrees Celsius. [From A. Takahashi, A. Yoshida, and M. Kawaguchi, Macromolecules, 15, 1196 (1982) (Ref. 1). Copyright 1982, American Chemical Society.]...

Lenk T J, Hallmark V M, Rabolt J F, Haussling L and Ringsdorf H 1993 Formation and characterization of self-assembled films of sulphur-derivatized poly(methyl methacrylates) on gold Macromolecules 26 1230-7... 

A polymer is a macromolecule that is constructed by chemically linking together a sequent of molecular fragments. In simple synthetic polymers such as polyethylene or polystyrer all of the molecular fragments comprise the same basic unit (or monomer). Other poly me contain mixtures of monomers. Proteins, for example, are polypeptide chains in which eac unit is one of the twenty amino acids. Cross-linking between different chains gives rise to j-further variations in the constitution and structure of a polymer. All of these features me affect the overall properties of the molecule, sometimes in a dramatic way. Moreover, or... 

Synthesis. The synthesis of poly(dichlotophosphazene) [25034-79-17, (N=PCl2) (4), the patent polymer to over 300 macromolecules of types (1) and (2), is carried out via controlled, ring-opening polymerization of the corresponding cycHc trimer, (N=PCl2)3 [940-71 -6]. 

The nomenclature of macromolecules can be compHcated when there is Httle or no regularity in the molecules for such molecules, the stmctural details may also be uncertain. In cases where the macromolecule is a polymeric chain with some uncertainties about regularity in its stmcture, a simple expedient is to name the polymer after the monomer that gave rise to it. Thus there are source-based names such as poly(vinyl chloride). 

Biomaterials with Low Thrombogenicity. Poly(ethylene oxide) exhibits extraordinary inertness toward most proteins and biological macromolecules. The polymer is therefore used in bulk and surface modification of biomaterials to develop antithrombogenic surfaces for blood contacting materials. Such modified surfaces result in reduced concentrations of ceU adhesion and protein adsorption when compared to the nonmodifted surfaces. 

N. A. Rotstein, T. P. Lodge. Tracer diffusion of linear polystyrenes in poly-(vinyl methyl ether) gels. Macromolecules 25.T 316-1325, 1992. 

Poly(phenylquinoxalines) containing acetylene groups in main chains of macromolecules 99MI28. 

Qiu et al. [241 have reported the synthesis of macromolecules having 4-tolylureido pendant groups, such as poly(N-acryloyl-N -4-tolylurea-cvi ethyl acrylate) [po-ly(ATU-co-EA)] 18, and poly(N-methacryloyl-A/ -4-tol-ylurea-co-EA) [poly(MTU-co-EA)] 19, from the copolymerization of ATU and MTU with EA, respectively. Graft copolymerization of acrylamide onto the surface of these two copolymer films took place using the Ce(lV) ion as initiator. The graft copolymerization is proposed as Scheme (12). 

Kim and Webster [57] were the first to show that trifunctional benzene-based monomers can also be used to synthesize poly(phenylene)s, in this case hyperbranched structures 31 based on 1,3,5-trisubstituled benzene cores. They self-condensed l,3-dibromophenyl-5-boronic acid leading to the formation of soluble, hyperbranched PPP-type macromolecule 31. 

It has been outlined by several authors that the single macromolecule may be irreversibly bound because of the large number of weakly interacting segments. The first papers on the construction of polymer-coated silica adsorbents involved the physical adsorption of water-soluble polymers. Polyethylene oxides [28, 29] and poly-/V-vinylpyrrolidone [30] are examples of the stationary phases of this type. 

An interesting aspect of the benzofuran cationic polymerization was uncovered by Natta, Farina, Peraldo and Bressan who reported in 196160,61 that an asymmetric synthesis of an optically active poly(benzofuran) could be achieved by using AlCl2Et coupled with (-)j3-phenylalanine, (+)camphorsulphonic acid or with (-)brucine. The optical activity was definitely due to the asymmetric carbon atoms in the polymer chain, indicating that at least some of the polymer s macromolecules possessed a di-isotactic structure, v/ z.62 ... 

---