Self-polycondensation

Polyimides (PI) are polycondensation products (1) prepared from derivatives of tetracarboxylic acids and primary diamines (1—5). Descriptions of self-polycondensation polymers (2) based on aminodicarboxylic acid derivatives are also found in the literature (6—9). 

Polysulfonation of self-polycondensation of 4-(phenylthio)benzenesulfonyl chloride was also used to prepare poly(arylene sulfide sulfone)s.245,246 Condensation of diphenyl sulfide with d -oxydibenzenesulfonic acid or d.d -thiodibcn/cnc-sulfonic acid247 or by poly etherification of poly condensation of DC DPS with d.d -dihydroxydiphenol sulfide occurred.5... 

Scheme 7. Self-polycondensation of AB2 type platinum-acetylide monomer...

On the other hand, self-polycondensation of AB2 type monomer 22 produced soluble polymer 23 M =16,QQQ,MJM =1.29,) [25] (Scheme 7). Concentration of the monomer showed little influence on the molecular weight of the resulting polymers. and NMR spectra suggested that the polymer has a hyper-branched sphere partially involving a cyclic structure. 

The self-polycondensation of molecules bearing two antagonist functions at their chain ends (denoted as AB) is more interesting since at any stage of the reaction, the polymer molecules always bear one A and one B function at the chain end. If one of these functions can be reacted subsequently with an unsaturated compound, the synthesis of macromonomers becomes possible. 

Self-polycondensation would be expected to compete with the reaction with the core, but it has been found that it is possible to drive the reaction to achieve the high degree of branching required. The resulting polymer has predominantly -OH terminal groups. 

This crosslinking agent suppresses the acid-catalyzed self-polycondensation [61]. DiphenyU-odonium 9,10-dimethoxyanthracene-2-sulfonate is used as a photoacid generator. 

Thus, the degree of polymerization for self-polycondensation depends on the equilibrium constant and the concentration of available monomer and water at equilibrium. The stoichiometry is also important with foreign polycondensations (see also Section 17.2.2). 

Hyperbranched polyimides can result due to the self-polycondensation reactions of AB2-, A2- and Bs-types. The preparation of hyperbranched polyimides involves chemical imidization of polyamic acid ester synthesized from AB2-monomers, which are carboxylic dianhydrides containing an ether bond and a diamine [6,19,76]. Polyamic acid in combination with a condensation agent is used because it is difficult to separate the synthesized polymer from AB2-type monomers. 

Other examples of self-polycondensation of an AB2-type monomer containing an imide-ring via etherification reactions can be found in the literature [7,10,77]. The selfpolycondensation can be performed though nucleophilic etherification of silylated phenol and aryl fluoride in diphenylsulfone at 240 °C under the presence of caesium fluoride... 

G. Yang, M. Jikei, M. Kakimoto, Successful thermal self-polycondensation of AB2 monomer to form hyperbranched aromatic polyamide. Macromolecules, 31, 5964—5966 (1998). 

Naturally occurring oleic acid and undecylenic acid derivatives can be used to S5mthesize semicrystalline PUs via an AB-type polycondensation. The AB-type monomers were self-polycondensed in two ways (17) ... 

If ricinoleic acid is the actual AB monomer, self-polycondensation leads to the corresponding polyester nsing conventional and enzymatic polyesterification catalysts [9, 10, 18] (Scheme 3.8). Ebata and co-workers [9] studied lipase-based bulk polycondensations applied to the methyl ester so that they could study this polymerisation in detail under green-chemistry conditions. The molecular weight of the ensuing polyesters was 2-100 kDa depending on the enzyme used, and the best results were obtained with lipase from Pseudomonas cepacia. 

Ueda, M., and K. MizoguehL 1997. Synthesis of polyearbonate by melt self-polycondensation of 4,4 -lsojHopylidenedi(p-phenylene)bis(2,2,2-trichloroethyl) carbonate. Polymer 38(13) 3369-3372. 

With polycondensation polymerization, two monomers join to produce dimers, trimers, tetramers, and higher ohgomers and finally polymers, plus a by-product which is usually H2O. HCl, NaCl, CH3OH, and other byproducts can be formed instead of water. When a single monomer is used instead of two monomers, the reaction is self-polycondensation polymerization. Stoichiometry is monitored and controlled when two different monomers are polymerized, but stoichiometry is ensured with selfpolycondensation. Most engineering thermoplastics can be produced by polycondensation polymerization ABS, PET, PBT, polyamides (nylons), polycarbonate, PAI, LCP, TPI, PEI, PPS, PPE, PSU, and PAEK. 

The transition temperature and transition heat for polyester MCLCP vary with the thermal treatment conditions. By changing the sample mass, heating rate and thermal treatment conditions, satisfactory results from DSC measurement for the rigid-rod MCLCP are usually obtainable. In some cases, self-polycondensation of polyesters proceeds continuously on thermal treatment by DSC. Thus, the relative molecular mass increases and a closer packed structure is obtained, resulting in more evident transition peaks. As the transition peaks on the DSC curve for the rigid-rod MCLCP are relatively small, careful inspection is necessary for their identification. When the sample is annealed at a temperature slightly below the isotropic transition temperature, more distinct peaks are frequently obtained. 

For the classic self-polycondensation of XAf, with equal and independent groups A, p, the conversion of A groups, is introduced in Eqs. (83). 

Jikei and Kakimoto have prepared the aromatic HBPAs and copolymers by direct polycondensation in the presence of condensation agents by (i) self-polycondensation of ABx-type monomers, (ii) copolymerization of AB and AB monomers and (iii) polymerization of A and B3 monomers [71]. The self-polycondensation of ABx monomers proceeded without gelation to form soluble polymers. Spectroscopic measurements revealed that the copolymers were composed of five kinds of repeating units. The inherent viscosity of the resulting PAs was low, in the range 0.2-0.4 dL/g. All of the resulting PAs were soluble in aprotic polar solvents, such as DMF, NMP and DMSO. The good solubility and adequate solution viscosity of the copol)nners allowed the preparation of transparent... 

As for step-growth-based polymerization methods. Fig. 1.3 shows two typical approaches in the preparation of hyperbranched chains (A) co-polycondensation [49-56] and (B) self-polycondensation [1, 23, 30-32, 40-48]. The co-polycondensation... 

Note that it is better to describe the self-polycondensation in terms of the average degree of polycondensation (DP) [10-13], instead of the number and weight... 

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