Polycondensation polymerization solution

Polyanhydrides based on unsaturated and fatty acid-derived monomers are shown in Table III. Poly(fumaric acid) (PFA) was fist synthesized by Domb et al. (1991) by both melt polycondensation and solution polymerization. The copolymer of fumaric acid and sebacic acid (P(FA-SA)) has been synthesized and characterized (Domb et al., 1991 Mathiowitz et al., 1990b). The mucoadhesive properties of this polymer... 

With appropriate precautions, condensation and addition polymerization reactions can be carried out in the same apparatus as customarily used for organic preparative work (see Sects. 4.1 and 4.2). In order to obtain high molecular weights by polycondensation in solution, a special circulation apparatus can be advantageously used with advantage (Fig. 2.4). 

Poly(amic acid)s were prepared by the polycondensations of dianhydrides (4 mmol) with alicyclic diamines (4 mmol) in HMPA (20 wt-% solid content) at room temperature for two days. An aliquot of the polymerization solution was... 

Polycondensation can be carried out by various polymerization techniques including melt polymerization, solution polymerization, interfacial polymerization, emulsion polymerization and solid-state polymerization. These polymerization processes will be summarized briefly in the following paragraphs. 

Solution polycondensation is used in industry to produce polyurethanes, polycarbonates and certain types of polyamides and polyesters. Polycondensation in solution is most frequently used when it is difficult or impossible to keep the reactants in the same phase using bulk polymerization, or when the melting point of the resulting polymer is too high. Solution polycondensation takes place at lower temperatures than melt polymerization and enables efficient heat transfer to be maintained due to lower viscosity. However, solution polycondensation requires polymer separation from solution, recovery of solvent, and polymer washing and drying. 

Interfacial polycondensation polymerization is an alternative to bulk polycondensation polymerization when bulk polymerization would require excessively high temperatures or generate high exothermic temperatures. Interfacial polycondensation polymerization is carried out at the boundary of two immiscible solutions. The monomer in one solvent at the interface reacts with the monomer in the other solvent at the interface of the two solvents. One solvent can be aqueous, and the other solvent is organic. When an emulsion is formed, the polymerization rate is determined by the diffusion rate and emulsion capsule surface area. Polymerization is very rapid. 

The choices are not always optimal. Solution and interfacial polycondensation polymerizations are used when bulk polymerization is too exothermic, as noted earlier. Polymerization combines processes such as polycondensation, bulk, graft, and solid-state polymerization or copolymerization. Three solid-state polymerization methods include... 

Synthetic Fiber and Plastics Industries. In the synthetic fibers and plastics industries, the substrate itself serves as the solvent, and the whitener is not appHed from solutions as in textiles. Table 6 Hsts the types of FWAs used in the synthetic fibers and plastic industries. In the case of synthetic fibers, such as polyamide and polyester produced by the melt-spinning process, FWAs can be added at the start or during the course of polymerization or polycondensation. However, FWAs can also be powdered onto the polymer chips prior to spinning. The above types of appHcation place severe thermal and chemical demands on FWAs. They must not interfere with the polymerization reaction and must remain stable under spinning conditions. 

Polyphosphates are also an important class of organophosphorus polymers. In addition to their flame-retardant characteristics, they possess attractive plasticizing properties and can be used as polymeric additives to other polymers [123-128]. In general, polyphosphates can be prepared by interfacial [119,129], melt [130], or solution polycondensation [131,132a,b]. Kricheldorf and Koziel [133] prepared polyphosphates from silylated bisphenols. 

The main polymerization method is by hydrolytic polymerization or a combination of ring opening as in (3.11) and hydrolytic polymerization as in (3.12).5,7 9 11 28 The reaction of a carboxylic group with an amino group can be noncatalyzed and acid catalyzed. This is illustrated in the reaction scheme shown in Fig. 3.13. The kinetics of the hydrolytic polyamidation-type reaction has die form shown in (3.13). In aqueous solutions, die polycondensation can be described by second-order kinetics.29 Equation (3.13) can also be expressed as (3.14) in which B is die temperature-independent equilibrium constant and AHa the endialpy change of die reaction5 6 812 28 29 ... 

It was assumed that linear polymeric particles are formed in the low water content solutions which show spinnability on the way of progressing hydrolysis-polycondensation reaction. In order to confirm this, the molecular weights and intrinsic viscosities of the solutions listed in Table 1 have been measured (2.). Figure 2 shows the log Mjj versus log[ri] plots. The slope of the plot a is larger than 0.5, that is, 0.75 and 0.64 respectively for solutions 1 and 2 of... 

Interfacial or solution polycondensation, with or without stirring, was the general procedure utilized for the preparation of the polyamides and polyureas.l a Details are given in Table I. An important point to be noted is that, in the unstirred interfacial condensation polymerization of 1 with sebacoyl chloride or tere-phthaloyl chloride in the organic phase and triethylamine as the proton acceptor, immediate film formation took place at the interface. The polyamide films were removed after 1 h, dried, and utilized for taking electron micrographs. 

Orthosilicic acid, Si(OH)4, could be an appropriate precursor, but it cannot be stored in monomeric form at reasonable concentrations in aqueous solutions. It enters easily into polycondensation reactions (1) that result in its polymerization. As a monomer, the orthosilicic add exists in aqueous solutions at a concentration of less than 100 ppm [18]. This is too small to fabricate sol-gel derived materials, although diatoms and sponges have the property of concentrating silica from seawater containing only a few mg per liter [60]. Sol-gel processing in the laboratory can be performed with a rather concentrated solution of orthosilicic add. This requires freshly prepared add the procedure is time consuming which restrids its widespread use. 

Microgels can not only be synthesized by polymerization but also by polycondensation or polyaddition [350]. In an early work on crosslinking of single linear macromolecules, it could be shown that if a crosslinking agent, such as terephthal dialdehyde, was added to a very dilute solution of a linear polymer such as polyvinyl alcohol, almost exclusively a intramolecular crosslinking of the individual macromolecules took place [351]. 

Polycondensation reactions of 2 with diphenols were carried out in DMAc at 160°C using an excess of potassium carbonate to yield viscous solutions ofthe desired poly(aryl ether ketone)s. Judging by the viscosity increase, the polymerization reaction was near completion after only about 8h at 160°C. Aqueous... 

For the polymerization, either in the melt or solid phase, the reaction is driven to the polymer by removing ethylene glycol. The polymerization reaction is typically catalyzed by solutions consisting of antimony trioxide or germanium oxide. Both polycondensation catalysts also catalyze the reverse reaction, which is driven by an excess of ethylene glycol at melt conditions, generally above 255 °C. The polymerization reaction follows second-order kinetics with an activation energy of 22 000 cal/mol [6],... 

The condensation polymerization process, employed recently by Skourlis et al. (1993) and Duvis et al. (1993), involves immersion of carbon fibers in a solution containing hexamethylenediamine and sodium carbonate. Dried carbon fibers are then immersed in a dipolychloride solution in carbon tetrachloride where the interfacial polycondensation reaction takes place. The result is that a thin layer of polyamide (nylon 6,6) coating is deposited on the continuous carbon fiber, whose thickness is controlled though by varying the diamine concentration. 

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