Condensative Chain Polymerization in Solid−Liquid Phase. Synthesis of Polyesters with a Defined Molecular Weight and a Narrow Molecular Weight Distribution by Polycondensation

Yokozawa, Tsutomu; Suzuki, Hideto

doi:10.1021/ja993224u

Cited by 47 publications

(35 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, it makes it clear that ring-opening polymerizations of amino acid NCAs and related heterocycles (when initiated by protic nucleophiles) represent exactly the same kind of condensative polymerizations as the chain polymerizations of non-cyclic Yokozawa and co-workers realized the syntheses of poly(4-hydroxybenzoate)s by a perfect condensative chain polymerization using alkyl-substituted 4-hydroxybenzoic acid derivatives with activated CO groups (Equation (36) and (37), Scheme 9). [44,51,63] The anion of the activated monomer reduces the electrophilicity of the CO group by delocalization (þM effect), but this effect is lacking in the oligoesters (3) which are more electrophilic. Furthermore, the 4-substituted electrophilic benzoic acid derivatives 4 and 5 ( Figure 2) were used as initiators to form dead endgroups on one side of the chain.…”

Section: Frommentioning

confidence: 99%

“…Considering that in a typical step-growth polymerization, 70 AE 5% of all products possess a molar mass M n a comparison of the MALDI-TOF mass spectrum with the M n (4 000 AE 1 000 Da) determined by SEC measurements suggested that more than 95% of all poly(ether ketone)s molecules had a cyclic core. Regardless to what extent an 'ab n '-based hyperbranched polymer has cyclized, addition of 'a 2 þ b 2 ' monomers will cause crosslinking and gelation because of the reaction of the a 2 monomers with the 'b'-function of the 'ab 2 ' monomer or its oligomers (44). A similar line of argument holds for syntheses of starshaped polymers from a small amount of an 'a n ' (or 'b n ') monomer and large amounts of 'ab' or 'a 2 þ b 2 ' monomers.…”

Section: Syntheses Of Hyperbranched and Star-shaped Polymersmentioning

confidence: 99%

See 1 more Smart Citation

Polycondensation of ‘a − b_n’ or ‘a₂ + + b_n’ Monomers ‐ A Comparison

Kricheldorf

2007

Macromol. Rapid Commun.

View full text Add to dashboard Cite

Characteristic similarities and differences in polycondensations of ‘a − b’ and ‘a2 + b2’ monomers are described including cyclic ‘a − b’ and cyclic ‘a2’ monomers. Polycondensations of ‘ab3’ monomers that yield (hyper)branched polymers are compared with polycondensations of ‘a2 + b3’ monomers that yield (hyper)branched, multicylic, or crosslinked polymers. In all cases the influence of cyclization reactions on structure and molecular weight of the reaction products is considered. Furthermore, the definitions of polycondensation and condensative chain polymerization are discussed along with a differentiation between kinetically controlled and thermodynamically controlled polycondensations.magnified image

show abstract

Section: Frommentioning

confidence: 99%

Section: Syntheses Of Hyperbranched and Star-shaped Polymersmentioning

confidence: 99%

Polycondensation of ‘a − b_n’ or ‘a₂ + + b_n’ Monomers ‐ A Comparison

Kricheldorf

2007

Macromol. Rapid Commun.

View full text Add to dashboard Cite

show abstract

“…[15] As the latter approach, we have reported the polycondensation of potassium 4-bromomethyl-2-octyloxybenzoate 1 with 18-crown-6 in acetone in the presence of 4-nitrobenzyl bromide 2 as an initiator. [16] In this polycondensation, we expected that solid monomers 1 dispersed in organic solvent do not react with each other, and that 1 transferred to organic solvent with 18-crown-6 would react with initiator 2 and the polymer end group in organic solvent. Our results have demonstrated that this system enables the synthesis of condensation polymers having a defined molecular weight and a narrow molecular weight distribution (M It has been reported that not only crown ethers but also onium salts serve as a phase transfer catalyst for solidliquid biphasic reactions.…”

Section: Introductionmentioning

confidence: 99%

Chain-Growth Polycondensation in Solid-Liquid Phase with Ammonium Salts for Well-Defined Polyesters

Yokozawa¹,

Maeda

Hiyama

et al. 2001

Macromol. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

The molybdenum–lead triple bond in the plumbylidyne complex shown is the first triple bond to a main‐group element of the sixth period. The small Mo–Pb bond and a linear coordination to the Pb atom are evident in the structure. Quantum‐chemical analysis with the electron localization function (reflected on the water) shows the electronic analogy between the plumbylidyne complex and Fischer carbene complexes. More about this can be found in the Communication by A. C. Filippou et al. on page 2243 ff.

show abstract

“…9 Although the M n s of the resulting polymers increased with the feed ratio of the monomer and initiator, those were different from calculated values. The phase transfer catalyzed polymerization of 4-bromomethyl-2-n-octyloxybenzoate was also investigated by Yokozawa et al 10 The M n of the resulting polyester was controlled up to 4000 with less than 1.3 of M w /M n . The first critical synthesis of a polymer with controlled M n (∼ 20000) and M w /M n (∼ 1.1) was achieved in the polyamide synthesis using 4-(Noctylamino)benzoic acid phenylester.…”

mentioning

confidence: 99%

Control of Molecular Weight Distribution in Polycondensation Polymers. Polyamide Synthesis

Shibasaki

Araki

Okazaki

et al. 2002

Polym J

View full text Add to dashboard Cite

ABSTRACT:Synthesis of the aromatic polyamide with a narrow molecular weight distribution (M w /M n ) was investigated via polycondensation. The new monomers, metal amide anions of 4-(N-octylamino)benzoylbenzoxazolin-2-thione (2) was prepared to prevent conventional polycondensation. The number average molecular weights (M n )s of the resulting polymer could be controlled varying the feed ratio of 2 and p-nitrobenzoyl chloride in the range of 10 3 -10 4 maintaining narrow M w /M n s (∼ 1.15 Controlled and living polymerizations allow the synthetic approach of well-defined polymers with controlled molecular weights (M n ), molecular weight distributions (M w /M n ), and terminal functionalities. 1 It has been realized in polymerizations of numerous molecules via anionic, 2 cationic, 3 radical, 4 coordination, 5 and group transfer systems. 6 However, most of these have strict limitations on the monomer structures for stabilization of propagating species in order to avoid side reactions such as termination and chain transfer. On the other hands, in step-growth polymerization, which generally possesses polymers having functionalities in their backbone, M n as well as M w /M n is somewhat difficult to control due to the statistical nature in its mechanism; the initiation, propagation, and termination reactions are essentially identical. Basic principle in polycondensation is that stoichiometric imbalance in monomer feed ratio decreases the degree of the polymerization, and that the polymerization should obey the Carothers equation to yield polymers with infinity at 100% conversion under ideal conditions. Thus, the M n and M w /M n control in stepgrowth polymerization is one of the most attractive subjects in polymer chemistry. Lenz et al. reported that the M n s of the poly(phenylene sulfide)s obtained by the aromatic nucleophilic substitutions of alkali metal 4-halothiophenoxides are higher than those predicted by the Carothers equation probably because of the different reactivity between the thiophenoxides in the monomers and those in the polymer chain ends. 7 Poly(p-phenylene sulfone) was synthesized by the self-condensation of sodium 4-halobenzenesulfonate, † To whom all correspondence should be addressed.where the addition of a small amount of 4-fluorophenyl sulfone greatly increases the yield of the resulting polymer, presumably by acting as an initiator for a chaintype polymerization. 8 The phase transfer catalyzed oxidative polymerization of 4-bromo-2,6-dimethylphenol in the presence of 2,4,6-trimethylphenol or 4-tert-butyl-2,6-dimethylphenol was investigated to control M n and M w /M n . 9 Although the M n s of the resulting polymers increased with the feed ratio of the monomer and initiator, those were different from calculated values. The phase transfer catalyzed polymerization of 4-bromomethyl-2-n-octyloxybenzoate was also investigated by Yokozawa et al. 10

show abstract

Condensative Chain Polymerization in Solid−Liquid Phase. Synthesis of Polyesters with a Defined Molecular Weight and a Narrow Molecular Weight Distribution by Polycondensation

Cited by 47 publications

References 10 publications

Polycondensation of ‘a − b_n’ or ‘a₂ + + b_n’ Monomers ‐ A Comparison

Polycondensation of ‘a − b_n’ or ‘a₂ + + b_n’ Monomers ‐ A Comparison

Chain-Growth Polycondensation in Solid-Liquid Phase with Ammonium Salts for Well-Defined Polyesters

Control of Molecular Weight Distribution in Polycondensation Polymers. Polyamide Synthesis

Contact Info

Product

Resources

About

Condensative Chain Polymerization in Solid−Liquid Phase. Synthesis of Polyesters with a Defined Molecular Weight and a Narrow Molecular Weight Distribution by Polycondensation

Cited by 47 publications

References 10 publications

Polycondensation of ‘a − bn’ or ‘a2 + + bn’ Monomers ‐ A Comparison

Polycondensation of ‘a − bn’ or ‘a2 + + bn’ Monomers ‐ A Comparison

Chain-Growth Polycondensation in Solid-Liquid Phase with Ammonium Salts for Well-Defined Polyesters

Control of Molecular Weight Distribution in Polycondensation Polymers. Polyamide Synthesis

Contact Info

Product

Resources

About

Polycondensation of ‘a − b_n’ or ‘a₂ + + b_n’ Monomers ‐ A Comparison

Polycondensation of ‘a − b_n’ or ‘a₂ + + b_n’ Monomers ‐ A Comparison