Alternating copolymers synthesis

Hilberer, A., et al. 1997. Poly(phenylenevinylene)-type conjugated alternating copolymers Synthesis and optical properties in solution. Macromol Chem Phys 198 2211. 

This feature of the interfacial preparation of poIy(iminocarbon-ates) has an important consequence for the synthesis of copolymers if the dicyanate component is structurally different from the diphenol, partial hydrolysis of the dicyanate will lead to the presence of two structurally different diphenol components that will compete for the reaction with the remaining dicyanate. The interfacial copolymerization will therefore result in a random copolymer. On the other hand, during solution polymerization no hydrolysis can occur. Since the dicyanates can only react with diphenols and vice versa, solution polymerization results in the formation of a strictly alternating copolymer. 

Controlling the exact architectnre of polymers has always attracted attention in macromolecular chemistry. Snccessfnl synthesis of alternating copolymers nsing ring opening metathesis polymerisation is of great interest also from a mechanistic perspective. NHC ligands were fonnd to be ideal to tune the selectivity of the metathesis initiators. 

Synthesis of strictly alternating copolymers can be achieved via various polymerisation techniques including poly-condensation or Ziegler-Natta polymerisations [123, 124]. 

It should be emphasized that for Markovian copolymers a knowledge of the values of structural parameters of such a kind will suffice to find the probability of any sequence Uk, i.e. for an exhaustive description of the microstructure of the chains of these copolymers with a given average composition. As for the composition distribution of Markovian copolymers, this obeys for any fraction of Z-mers the Gaussian formula whose covariance matrix elements are Dap/l where Dap depend solely on the values of structural parameters [2]. The calculation of their dependence on time, and the stoichiometric and kinetic parameters of the reaction system permits a complete statistical description of the chemical structure of Markovian copolymers to be accomplished. The above reasoning reveals to which extent the mathematical modeling of the processes of the copolymer synthesis is easier to perform provided the alternation of units in macromolecules is known to obey Markovian statistics. 

A 1992 patent describes the carbonylation of EO to yield /3-propiolactone using a mixture of Co2(CO)8 and 3-hydroxypyridine.982 A recent re-investigation of this system has indicated that the major product is the alternating copolymer, a polyester, catalyzed by the [Co(CO)4] anion (Scheme 24).983 The synthesis of lactones via this methodology has successfully been achieved using Lewis acidic counter-cations (Scheme 25) 984,985 a similar strategy allows /3-lactams to be... 

A similar technique was applied to the synthesis of AB and ABA block copolymers containing random and alternating copolymer sequences [178-180]. For example poly(St-ra dora-MMA)-hZock-poly(VAc), poly(VAc-hZock-poly(St-ran-dora-MMA)-hZock-poly(VAc), poly(St)-foZoc/c-poly(DiPF-aZMBVE), poly(IBVE-aZf-MAn)-hZock-poly(St)-hZock-poly(IBVE-aZf-MAn), poly(St)-hZock-poly(EA)-random-AA), and poly(St)-hZock-poly(EA-ra dora-AA-random-MMA) were synthesized [178]. 

SCHEME 2.30 Synthesis of the Frechet-type dendrimer-substituted PFs and fluorene random and alternating copolymers. (From Marsitzky, D., Vestberg, R., Blainey, P., Tang, B.T., Hawker, C.J., and Carter, K.R., J. Am. Chem. Soc., 123, 6965, 2001.)... 

S.-H. Jin, M.-Y. Kim, D.-S. Koo, and Y.-I. Kim, Synthesis and properties of poly(fluorene-a/t-cyanophenylene vinylenej-based alternating copolymers for light-emitting diodes, Chem. Mater., 16 3299-3307, 2004. 

J.K. Herrema, P.F. van Hutten, R.E. Gill, J. Wildeman, R.H. Wieringa, and G. Hadziioannou, Tuning of the luminescence in multiblock alternating copolymers. 1. Synthesis and spectroscopy of poly[(silanylene)thiophene]s, Macromolecules, 28 8102-8116, 1995. 

Though important results have already been obtained in the carbonylation of olefins, the field still remains open. Development of more active, efficient and stable catalysts based also on less expensive metals will make the carbonylation processes more attractive. Carbonylation of less common olefins, including functionalised ones, has to be explored in more depth. Other important targets are the efficient living copolymerisation, the multiple olefin insertion producing non-alternating copolymers and the selective synthesis of unsaturated products like acrylates and methacrylates. 

Wang SJ, Du LC, Zhao XS, Meng YZ, Tjong SC (2002) Synthesis and characterization of alternating copolymer from carbon dioxide and propylene oxide. J Appl Polym Sci 85 2327-2334... 

This chapter is concerned primarily with the simultaneous polymerization of two monomers to produce statistical and alternating copolymers. The different monomers compete with each other to add to propagating centers, which can be radical or ionic. Graft and block copolymers are not synthesized by the simultaneous and competititive polymerization of two monomers. Each monomer undergoes polymerization alone. A sequence of separate, noncompetitive polymerizations is used to incorporate the different monomers into one polymer chain. The synthesis of block and graft copolymers and variations thereof (e.g., star, comb) are described in Secs. 3-15b-4, 3-15b-5, 5-4, and 9-9. 

Finally, it should be mentioned that there exist two other routes for the synthesis of copolymers. First the partial chemical conversion of homopolymers (see Sect. 5.1), for example, the partial hydrolysis of poly(vinyl acetate). Secondly, by homopolymerization of correspondingly built monomers. An example for these macromolecular compounds, sometimes called pseudo-copolymers, is the alternating copolymer of formaldehyde and ethylene oxide synthesized by ringopening polymerization of 1,3-dioxolane. 

Secondly, the quaternised monomer may be replaced with a weakly basic monomer such as MEMA, which exists in its neutral, non-protonated form in alkaline media. Thus the desired zwitterionic block copolymer is prepared in its anionic/neutral form so that no isoelectric point is encountered during the copolymer synthesis. Afterwards, the solution pH can be adjusted to the isoelectric point by the addition of acid to protonate the weakly basic MEMA residues and precipitate the copolymer, which might be a useful alternative approach to column chromatography for the efficient removal of the ATRP catalyst. 

The cationic isomerization polymerization of 4-methyl-l-pentene is of interest because the completely isomerized structure can be viewed as a perfectly alternating copolymer of ethylene and isobutylene, a structure which cannot be synthesized by conventional techniques. One of the difficulties encountered in the study of this polymer was the lack of an accurate structure determination method necessary for a detailed correlation of synthesis conditions and polymer microstructure. The work described in this paper attempts to provide such a correlation. 

Polyolefin ketone synthesis (the alternating copolymer of ethylene and carbon monoxide E. Drenth, Shell) later marketed as Carilon by Shell and BP First commercial use of PA6/clay nano-composites for timing belt covers by Toyota, Japan... 

The number of this kind of periodic copolymer is rapidly increasing [238]. The existence of DA complexes naturally offers a much broader choice for the synthesis of alternating copolymers. 

Title Synthesis of A,B-Alternating Copolymers by Olefin Metathesis Reactions of Cyclic Olefins or Olefinic Polymers with an Acyclic Diene... 

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