Alternating and random

In a large number of investigations the possibility of the formation of polymer-polymer complexes with the participation of alternating and random copolymers has been shown. So, using the viscometric method58, the complex formation of iso-PMAA and methyl methacrylate and methacrylic add copolymer has been reported. The stability of the stereocomplex decreases with increasing add content in the copolymer. 

The authors of this article have studied the properties of a series of complexes of alternating and random " ) copolymers with nonionic polymers (Tables... 

Analysis of the fluorescence decay curves in water indicated that the intracoil process is static and that anthryl aggregation induces non-exponentiality in the fluorescence decay associated with a dynamic equilibrium between the singlet diphenyl-anthracene and a non-fluorescent dimer state. Further evidence was also presented to show that these polymers self-organise into hydrophobic and hydrophilic regions Energy migration in alternative and random copolymers of 2-vinylnaphthalene and methyl methacrylat methacrylic acid... 

For comparison with the alternating copolymer we synthesized a randcm polymer of 2-VN and MA containing ca. 10 mol of 2-VN (higher naphthyl contents did not dissolve In basic H O). Solubilization by this copolymer demonstrates 1) a much lower sensitization efficiency than the alternating copolymer, 2) no spectral shift between directly excited and sensitized AnOH, and 3) In the absense of AnOH a clearly discernible exclmer component In the fluorescence (see Fig. 7). While comparison of the alternating and random copolymer Is dangerous because of the different naphthyl contents, these results do Imply that 1) the AnOH Is not preferentially associated with the naphthyl moieties In the random copolymer, and 2) the red-shift observed In the sensitized AnOH fluorescence for P(2VN-alt-MA) is the result of naphthalene - anthryl Interactions. 

Most of the calculations in the earlier chapters dealt with homopolymers. The techniques developed in this book can also be used to calculate the physical properties of alternating and random copolymers. The prediction of the properties of alternating copolymers will be discussed in Section 17.D. It will also be shown how the prediction of the properties of some homopolymers can be simplified by formally breaking their repeat units down into the smaller alternating repeat units of homopolymers whose properties have already been calculated. The calculation of the properties of random copolymers will be discussed in Section 17.E. 

Solvent effects on the optical densities of alternating and random copolymers of styrene and methyl methacrylate can explain the variation in hypochromism at 269.5 nm (see Figure 1 and Table II). Actually, the hypochromism seems to depend on specific interactions between methyl methacrylate mers and styrene mers. Good correlations between hypochromism and chemical structure of the copolymers can be deduced on the basis of the sequence length distribution. 

Synthetic copolymers are produced to improve certain properties, or even as the only means of attaining these properties. Here, alternating and random polymers are synthesized in one step from a mixture of A and B monomers, or are obtained by transformation of an already synthesized... 

Montaudo, G., Scamporrino, E., and Vitalini, D., Characterization of Copolymer Sequences by FAB-MS. II. Identification of oligomers contained in the Alternating and Random Copolyesters with Photolabile Units in the main chain. Macromolecules, 22, 627 (1989). 

Figure 1. Synthetic route for alternating and random copolymers of arylene vinylenes...

Aromatic oxadiazoles. See Oxadiazole-based polymers Arylene-vinylene copolymers alternating and random copolymerization, 346-348... 

W.-C. Wu a, C.-L. Liu, W.-C. Chen, Synthesis and characterization of new fluorene-acceptor alternating and random copolymers for light-emitting applications. Polymer, 47, 527-538 (2006). 

Both reactivity ratios are smaller than unity ri < 1 and /-2 < 1 or Aril composition curve crosses the diagonal in an azeotropic point. In this azeotropic point the incorporation ratio of both monomers equals the monomer composition, so there is no preferential reaction of one of the monomers (curve b in Fig. 8.1). 

The tendency for alternation of monomers in a styrene-maleic anhydride and styrene-acrylonitrile copolymers at moderate temperatures has been attributed to the formation of a charge transfer complex (CTC) between a donor (D) and an acceptor (A). This CTC is readily detectable by UV or nmR spectroscopy. More important, the equilibrium constant decreases as the temperature is increased and this effect can be followed by instrumental analysis. Thus it is possible to extrapolate to a higher temperature at which the CTC does not exist (16). Thus, by proper temperature control, it is possible to produce SMA alternating copolymers, block copolymers of vinyl monomers with both alternating and random SMA (17) and completely random copolymers of SMA (18). Half esters of SMA have been used as viscosity control agents in petroleum crudes (19). 

Fig. 8.27. Temperature dependence of Young s modulus of a copolymer. Alternating and random copolymers have a glass temperature between both basic polymers graft and block copolymers behave like semi-crystalline thermoplastics (possessing two transition temperatures) [97]...

Bai F, Chang CH, and Webber SE. Photon-harvesting polymers Singlet energy transfer in anthracene-loaded alternating and random copolymers of 2-vinyInaphthalene and methacrylic acid. Macromolecules 1986 19 2484-2494. 

Montaudo G, Scamporrino E, Vitalini D. Characterization of copolymer sequences by fast atom bombardment mass spectrometry. 2. Identifieation of ohgomers contained in alternating and random copolyesters with photolabde units in the main chain. Macromolecules 1989 22 627-632. 

A strong pyrene (3.129) emission was observed when certain block, alternate and random styrene-butadiene rubber films were subjected to intense UV irradiation in vacuum. The proposed mechanism for pyrene formation is [8] ... 

Variations in Sequencing of Copolymer Repeat Units. Whether it is a homopolymer possessing differences in repeat unit structures, a copolymer or terpolymer, the sequencing of repeat units can cause wide variations in physical properties. The most fundamental structural categories for copoljmaers, terpoly-mers, etc. are block, alternating and random structures ... 

The alternating polymer shows large hydrophobic and hydrophilic domains with a poor continuity between the hydrophilic domains. The random copolymer exhibits a disordered morphology with some connectivity between the hydrophilic regions, but no well-defined ionic pathways for the proton or water transport. On the other hand, the multiblock copolymer shows a well-defined fingerprint-type structure with continuous hydrophilic and hydrophobic pathways. The authors concluded that this microstructure was probably responsible for the fast proton transport even at a low humidity, as well as the faster water transport than those of the alternating and random polymers. 

Rana D, Mounach H, Halary JL, Monnerie L. Differences in the mechanical behaviour between alternating and random styrene-methyl methacrylate copolymers. J Mater Sci 2005 40(4) 943-953. 

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