Solution poly condensation

Bifunctional acid chlorides and diamines can react in a single oi anic phase to form polyamides. The term solution poly condensation is used to describe two major processes that differ in their product, though the reactions probably follow similar mechanisms. In one group of polycondensations, polymer is precipitated as it forms or as it achieves a range of... 

As in the case of interfacial polycondensation, there is very little reported work on the kinetic and related aspects of low-temperature solution poly condensation. 

Solution poly condensation polymerization is used when the temperatures needed to melt the monomer are too high or when bulk (mass) polymerization is too exothermic and hazardous. With solution polymerization, monomers and polymerization initiators are dissolved in a nonmonomeric liquid solvent at the start of polymerization. The solvent is usually a solvent for the polymer and copolymer product. 

In this study, polyesters [XII] having syringyl-type biphenyl units were synthesized from 4,4 -dihydroxy-3,3, 5,5 -tetramethoxybiphenyl (XI) which was prepared from 2,6-dimethoxyphenol (11). As shown in Scheme 6, polyesterification of XI with terephthaloyl, isophthaloyl and sebacoyl chloride were carried out by the low temperature solution polycondensation and by the interfacial poly condensation. The polyterephthalate with r/inh = 1 42 dl/g was obtained by the interfacial poly condensation. The polyisophtha-late with r/inh = 0.73 dl/g and the polysebacate with r/inh = 0.43 dl/g were obtained by the low temperature solution poly condensation. 

Melt poly condensation The reaction is carried out in a 250-mL stainless steel vessel with nitrogen inlet and mechanical stirrer. The vessel containing T4T-dimethyl (30 g, 72.8 mmol) and ethanediol (30 g, 0.48 mol) is heated up in an oil bath at 200°C. After 15 min reaction TiO -OCaJ I7 )4 (1.5 mL of 0.1 M solution in CH2C12) is added and subsequently the temperature is gradually raised to 260°C (l°C/min). After 10 min at 260°C the pressure is reduced (15-20 mbar) for 5 min. Then the pressure is reduced further (<2.5 mbar) for 45 min. The vessel is cooled down slowly to room temperature, maintaining the low pressure. After solidification, the polymer is ground (particle size <1 mm) and subsequently dried in a vacuum oven at 80°C. 

Test results for a series of reactions of polyfunctional amino acids with CDI in aqueous solution are reported in reference [51]. Serine and threonine did not poly-condense. Instead, via the iV-imidazolyl-carbonyl amino acids, L-2-oxooxazolidine-4-carboxylic acid or L-(+)-fraw,s-5-methyl-2-oxooxazolidine-4-carboxylic acid were obtained. 

Freeder, B. G. et al., J. Loss Prev. Process Ind., 1988, 1, 164-168 Accidental contamination of a 90 kg cylinder of ethylene oxide with a little sodium hydroxide solution led to explosive failure of the cylinder over 8 hours later [1], Based on later studies of the kinetics and heat release of the poly condensation reaction, it was estimated that after 8 hours and 1 min, some 12.7% of the oxide had condensed with an increase in temperature from 20 to 100°C. At this point the heat release rate was calculated to be 2.1 MJ/min, and 100 s later the temperature and heat release rate would be 160° and 1.67 MJ/s respectively, with 28% condensation. Complete reaction would have been attained some 16 s later at a temperature of 700°C [2], Precautions designed to prevent explosive polymerisation of ethylene oxide are discussed, including rigid exclusion of acids covalent halides, such as aluminium chloride, iron(III) chloride, tin(IV) chloride basic materials like alkali hydroxides, ammonia, amines, metallic potassium and catalytically active solids such as aluminium oxide, iron oxide, or rust [1] A comparative study of the runaway exothermic polymerisation of ethylene oxide and of propylene oxide by 10 wt% of solutions of sodium hydroxide of various concentrations has been done using ARC. Results below show onset temperatures/corrected adiabatic exotherm/maximum pressure attained and heat of polymerisation for the least (0.125 M) and most (1 M) concentrated alkali solutions used as catalysts. 

Bis(hydroxymethyl) furan and 5-hydroxymethyl furfural (available from C6 sugars) have been oxidized to furan-2,5-dicarboxylic acid (44)- Linear polyesters, polyurethanes, and polyamides containing these monomers have been described in the literature (45-43) and have been made via condensation polymerization techniques including bulk, solution, and interfacial mixing procedures. Gandini (5,34) reviewed the poly condensation reactions up to 1986 and... 

The purpose of this work is then to study similar B(CgFj)3-catalyzed poly condensation of hydrido and methoxy functionalized silanes and siloxanes in solution, in a view to prepare hybrid silicones (see general reaction pathway in Scheme 1). We considered three routes, first a model reaction to prepare PDMS and two others to synthesize different hybrid silicones, starting from hydrido and methoxy functionalized bricks. 

Reported values for the activation enei of the amidation reaction vary. For the melt poly condensation of aminoundecanoic acid the activation energy was found to be [87] 11 kcal mole for the polycondensation of the same acid as a 30% solution in m-cresol, the reported [92] activation energy is 31 kcal mole". The activation energy of the second-order melt polycondensation of p-aminophenylalkanoic acids was reported [93] to be between 17 emd 19 kcal mole". ... 

As with interfacial polycondensation an acid-acceptor is necessary to neutralize the hydrochloric acid formed in the reaction. These low-temperature poly condensation reactions are irreversible, and the acid-acceptor is necessary only to keep the reacting diamine free for reaction with the acid chloride. iV,iV-Dimethylacetamide and related solvents are often employed. Ar,A-Dimethylformamide cannot be used as it reacts with the acid chloride, and only low-molecular-weight polymer results. These amide solvents form loose complexes with the hydrochloric acid produced during the polymerization, and no additional acid-acceptor is needed. However, the final solutions are usually neutralized to minimize corrosion of metallic equipment during later steps such as spinning, and to provide small amounts of water often found necessary for the long-term stability of the polymer solutions [111]. 

A diamine solution in water and a diacid chloride solution in hexane are prepared. A porous substrate membrane is then dipped into the aqueous solution of diamine. The pores at the top of the porous substrate membrane are filled with the aqueous solution in this process. The membrane is then immersed in the diacid chloride solution in hexane. Because water and hexane are not miscible, an interface is formed at the boundary of the two phases. Poly condensation of diamine and diacid chloride will take place at the interface, resulting in a very thin layer of polyamide. The preparation of composite membranes by the interfacial in situ polycondensation is schematically presented in Fig. 3. 

Frolov, Shabanova, and co-workers (37-39) studied the transition of a sol into a gel and the aggregate stability of colloidal silica. Their aim was to develop a technology for the production of highly-concentrated silica sols and to use them as binders, catalyst supports, polymer fillers, adsorbents, and so forth. Kinetic studies were made of polycondensation and gel formation in aqueous solutions of silicic acids. At the stage of particle growth, poly condensation proceeds in the diffusion-kinetic region. With changes in pH, temperature, concentration, and the nature of electrolytes,... 

A number of hydroxylated water soluble polymers were examined as coreactants with polymer 52 in the absence of calcium alginate, and were judged on the basis of the rate of gel formation and the physical properties of the gel These polymers included sodium alginate, polyvinyl alcohol, and copolymers of HEMA with MAA. Of the polymers tested, best results were obtained with polymer 10a, a copolymer of HEMA with a mole fraction of about 10% MAA, which rapidly produced an elastic gel on exposure to polymer 52 in solution. Simple condensation of the carboxyls in polymer 10a with the epoxide functionality was ruled out as a competing reaction due to the measurable but slow reaction between polymer 52 and poly methacrylic acid. It is, therefore, likely... 

We determined that vicinal dihydroxy organic reagents stabilize the soluble forms of silica. The stability of monosilicic acid solution is determined by the structure of the stabilizer ethylene glycol and humic acids do not stabilize soluble forms of silica enough, but glycerin and catechol stabilize the silica solution when they are added at 5 - 7% to the solution. This fact is connected with the formation of hydrogen bonds and stable penta- and hexacoordinated compounds, preventing the processes of poly condensation of silica in solution. 

Interfacial and solution polycondensations are commercially important. For example, an unstirred interfacial poly condensation reaction is utilized in the production of polyamide fibers. Another important application of interfacial polycondensation is the enhancement of shrink resistance of wool. The wool is immersed first in a solution containing one of the reactants and subsequently in another solution containing the other reactant. The polymer resulting from the interfacial reaction coats the wool and improves its surface properties. 

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