“…Higher % of cis configuration may be conveniently explained by a participation of the charge-transfer complex of styrene and maleic anhydride , The mechanism, adapted to the present case, is presented in Scheme . 1 Proposed Mechanism for the Formation of Z (cis)- and E (trans)-Man Units via CTC Complex Addition, Showing Attack by the Radical Chain Yielding (a) a Z-Man Unit and (b) an E-Man Unit …”
Section: Resultsmentioning
confidence: 98%
“…c Calculated by the relative areas of the peaks at 51.5 and 52.5 ppm in 13 Butler et al proposed a stereoregulatory mechanism based on the maximum orbital overlap theory of Mullikin, for the formation of a cis succinimide unit in copolymers of Nsubstituted maleimide with vinyl ethers, which was used for explanation of St/Man copolymerization by Brown. 42,43 The mechanism, adapted to the present case, is presented in Scheme 1.…”
Section: Structure and Composition Of St-manmentioning
Radical copolymerization of styrene (St) and maleic anhydride (Man) was performed in supercritical
carbon dioxide (SC CO2) at 50−80 °C with 2,2‘-azoisobutyronitrile as the initiator. A novel, ultrahigh molecular
mass St−Man alternative copolymers (M
w > 106) has been synthesized. The NMR spectra demonstrated that the
copolymers obtained possess strictly alternating structure. Aqueous solutions of the alternative copolymers exhibit
lower critical solution temperatures (LCST). These LCST's are highly sensitive to changes in the molecular
weight and pH. St/MAn copolymerization in SC CO2 as the solvent yielded higher molecular weight products
and more cis configuration linkage of cyclic MAn units in the copolymer chains than those made in common
organic solvents. These facts demonstrate that SC CO2 as the solvent plays an important role in the copolymerization
of styrene with maleic anhydride, originating from the special intermolecular interactions between SC CO2 and
St−Man alternative copolymer.
“…Higher % of cis configuration may be conveniently explained by a participation of the charge-transfer complex of styrene and maleic anhydride , The mechanism, adapted to the present case, is presented in Scheme . 1 Proposed Mechanism for the Formation of Z (cis)- and E (trans)-Man Units via CTC Complex Addition, Showing Attack by the Radical Chain Yielding (a) a Z-Man Unit and (b) an E-Man Unit …”
Section: Resultsmentioning
confidence: 98%
“…c Calculated by the relative areas of the peaks at 51.5 and 52.5 ppm in 13 Butler et al proposed a stereoregulatory mechanism based on the maximum orbital overlap theory of Mullikin, for the formation of a cis succinimide unit in copolymers of Nsubstituted maleimide with vinyl ethers, which was used for explanation of St/Man copolymerization by Brown. 42,43 The mechanism, adapted to the present case, is presented in Scheme 1.…”
Section: Structure and Composition Of St-manmentioning
Radical copolymerization of styrene (St) and maleic anhydride (Man) was performed in supercritical
carbon dioxide (SC CO2) at 50−80 °C with 2,2‘-azoisobutyronitrile as the initiator. A novel, ultrahigh molecular
mass St−Man alternative copolymers (M
w > 106) has been synthesized. The NMR spectra demonstrated that the
copolymers obtained possess strictly alternating structure. Aqueous solutions of the alternative copolymers exhibit
lower critical solution temperatures (LCST). These LCST's are highly sensitive to changes in the molecular
weight and pH. St/MAn copolymerization in SC CO2 as the solvent yielded higher molecular weight products
and more cis configuration linkage of cyclic MAn units in the copolymer chains than those made in common
organic solvents. These facts demonstrate that SC CO2 as the solvent plays an important role in the copolymerization
of styrene with maleic anhydride, originating from the special intermolecular interactions between SC CO2 and
St−Man alternative copolymer.
“…It has been suggested that, if an EDA complex participate in a copolymerization, some structural evidences related to the structure of the complex may be found in the copolymer [24,28,29,31]. It has been also suggested [32] that the relative amounts of the cis and trans linkage configurations at the succinimide rings in the copolymers are closely related to the quantitative role of the EDA complex in alternating copolymerization. Fujimori et al [33] claimed that the presence of the cis linkage configuration of maleimide unit in the copolymers could be considered as a structural evidence for the participation of the EDA complex in the propagation step.…”
Section: The Influence Of the Reaction Conditions On The Characteristmentioning
“…In recent studies of alternating copolymerization systems in which CTCs are formed between pairs of electron‐rich and electron‐deficient comonomers, a link has been found to exist between the alternating tendency and the stereoregularity of comonomer units 45, 54, 55. In such cases, the ratio of cis configurations to trans configurations was found to increase along with the tendency of the comonomers to alternate 56. It has been also suggested that the relative amounts of the cis‐ and trans‐linkage configurations at the succinimide rings in the copolymers are closely related to the quantitative role of CTC in alternating copolymerization.…”
A surface-active p-vinyl benzyloxy--hydroxy-poly(ethylene oxide) macromonomer containing 22 pendant structural units of ethylene oxide (St-PEO 22 ) was synthesized with an initiation method. Because of its solubility in a large variety of solvents, the free-radical copolymerization with electron-acceptor N-phenylmaleimide (NPMI) was performed at 60°C in benzene and tetrahydrofuran (THF) as isotropic media and in a water-THF mixture or water as a heterogeneous medium. Oil-soluble 2,2Ј-azobisisobutyronitrile and water-soluble 4,4Ј-azobis(4-cyanovaleric acid) were used as the initiators at fixed concentrations. Two different St-PEO 22 /NPMI comonomer ratios (1/1 and 3/7) at a fixed total comonomer concentration in the polymerization system were used. The structures, compositions, and microstructure peculiarities of the obtained alternating, amphiphilic, comblike copolymers were determined by NMR analysis. For the copolymers synthesized in hydrophilic media, differential scanning calorimetry showed, near the endothermic peak attributed to the melting of the poly-(ethylene oxide) side chains, the presence of a second peak due to the partially ordered phase that could exist between the crystalline state and the isotropic melt. Also, the thermal stability of the obtained copolymers was studied with thermogravimetric analysis.
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