Terephthalic acid, polycondensation with

Polycondensation reactions were also carried out using a mixture of ethylene-diamine and adipic acid (55). IR techniques again were used to confirm the polymer composition. The results are summarized on Table 9. The chemistry of polyethylene terephthalate) mechanical polycondensation with diamines proceeds as follows ... 

Polybutylene terephthalate (PBTP, PBT, and polytetramethylene terephthalate) n. A member of the polyalkylene terephthalate family, similar to polyethylene terephthalate in that it is derived from a polycondensate of terephthalic acid, but with butanediol rather than glycol. PBTP can be modified easily to overcome its relatively low-operating-temperature limit, making it equivalent to plastics used in... 

Strong interaction between monomers and the template is a prerequisite for the template process, while in simple polycondensation high temperature and low pressure is applied. However, in mild conditions using the direct polycondensation method it was demonstrated that terephthalic acid connected with poly(4-vinylpyridine) (79), poly(ethylene oxide) (80), poly(vinylp5UTolidinone) (81) and activated by triphenyl phosphite reacts with hexamethylenediamine, giving polyamides with high molecular weight. 

Condensation polymerization differs from addition polymerization in that the polymer is formed by reaction of monomers, each step in the process resulting in the elimination of some easily removed molecule (often water). E.g. the polyester polyethylene terephthalate (Terylene) is formed by the condensation polymerization (polycondensation) of ethylene glycol with terephthalic acid ... 

The material, Hostamid, LP700, is said to be a melt polycondensate of the diamines (I) and (II) above with terephthalic acid and up to 70% of e-caprolactam but has never been commercially marketed. 

Note-. Bisphenol-A and the diaryl esters of terephthalic acid and isophthalic acid are nonvolatile compounds, so that any excess of these components cannot completely be removed, resulting in a low-molar-mass, unusable polyester. Moreover, excess bisphenol-A causes a strong discoloration of the polyester melt due to thermal degradation at the high reaction temperature used. This can be avoided if the diaryl esters are mixed with 5 mol% of diphenyl carbonate. Any excess of this compound can easily be removed in vacuum at the polycondensation temperature. 

PET is a polycondensation polymer based on the reaction of terephthalic acid (TA) and mono-ethylene glycol (MEG) or alternatively with di-methyl terephtha-late (DMT) plus MEG (Figure 10). 

PTT is made by the melt polycondensation of PDO with either terephthalic acid or dimethyl terephthalate. The chemical structure is shown in Figure 11.1. It is also called 3GT in the polyester industry, with G and T standing for glycol and terephthalate, respectively. The number preceding G stands for the number of methylene units in the glycol moiety. In the literature, polypropylene terephthalate) (PPT) is also frequently encountered however, this nomenclature does not distinguish whether the glycol moiety is made from a branched 1,2-propanediol or a linear 1,3-propanediol. Another abbreviation sometimes used in the literature is PTMT, which could be confused with poly(tetramethylene terephthalate),... 

Specifically, the co-polycondensation reaction of the dihydroxy[2]catenand 50b with the terephthalic acid derivative 47 does not proceed to high molecular-weight but affords preferentially the cyclic oligo[2]catenands 52 with n= 1,2,3 as shown by matrix-assisted time-of-flight mass spectrometry (MALDI-TOFMS) [56]. Besides the high structural flexibility of the dihydroxy[2]catenand 50b, an-... 

Shimada and coworkers recently reported the synthesis of the poly[2]catenand 56, which is structurally related to the poly[2]catenand 51b (Scheme 20) [60]. Similarly to what has been observed for the co-polycondensation of the dihy-droxy[2]catenand 50b with the terephthalic acid derivative 47, the reaction of the diamino[2]catenand 53 with adipoyl dichloride affords mainly the Pretzel -shaped compound 54 [3, 41, 60]. The poly[2]catenand 56 has been obtained via the polycondensation of the diamino[2]catenate 54 with adipoyl dichloride, yielding the poly[2]catenate 55. Subsequently, the demetalation of the latter affords the linear poly[2]catenand 56 with M = 8.1xl05, using polystyrene standards, which corre-... 

Poly[(benzo[l,2-d 4,5-d ]bisthiazole-2,6-diyl)-l,4-phenylene] (PBT) can be conveniently prepared by the polycondensation of 2,5-diamino-1,4-benzenedithiol dihydrochloride with terephthalic acid in poly(phosphoric acid) (PPA) according to the equation shown in Fig. 14. 

Reactions of the Methyl Groups. These reactions include oxidation, polycondensation, and ammoxidation. PX can be oxidized to both terephthalic acid and dimethyl terephthalate, which are then condensed with ethylene glycol to form polyesters. Oxidation of OX yields phthalic anhydride, which is used in the production of esters. These are used as plasticizers for synthetic polymers. MX is oxidized to isophthalic acid, which is also converted to esters and eventually used in plasticizers and resins (see Phthalic ACIDS and otherbenzenepolycarboxylic acids). 

Polymer was prepared as follows. Bis (/3-hydroxyethyl) terephthalate (4/14 mole) reacted with terephthalic acid (TA) (3/14 mole) at 275°C using Sb203 as polycondensation catalyst. To the resulting polymer ([17] 0.41, COOH content 51.3 eq/10 g, and diethylene glycol content 0.60 mole %/TA) was added POC, followed by 15 minutes at high vacuum. 

C0-p-C6H4-C00CH2CLt20)n-, a synthetic polyester prepared by esterification of terephthalic acid with methanol and subsequent polycondensation of the ester with ethylene glycol. 

In contrast to polymerisates, polycondensates can not be depolymerized under inert conditions. Decomposition usually leads to the destruction of the chemical structure and the monomers. The thermal decomposition of PET starts at about 300°C in an inert atmosphere [25]. Between 320 and 380°C the main products are acetaldehyde, terephthalic acid, and carbon oxides under liquefaction conditions. The amounts of benzene, benzoic acid, acetophenone, C1-C4 hydrocarbons, and carbon oxides increase with the temperature. This led to the conclusion that a P-CH hydrogen transfer takes place as shown in Eigure 25.8 [26]. Today the P-CH-hydrogen transfer is replaced as a main reaction in PET degradation by several analytic methods to be described in the following sections. The most important are thermogravimetry (TG) and differential scanning calorimetry (DSC) coupled with mass spectroscopy and infrared spectroscopy. 

Aromatic dicarboxylic acids, even with aromatic diamines and aromatic amino acids, do not form high viscous polymers. Isophthalic acid (IPA) gives higher viscous polymers than terephthalic acid. From this result it may be concluded that polycondensation is favored with higher solubility of polymer. 

Kricheldorf has reported the synthesis of lyotropic poly(amide-imide)s and poly(benzoxazole-amide)s. These were prepared by the polycondensation of N,N-bis(trimethylsilyl)-p-phenylenediamine or N,AT -bis(trimethylsilyl)-3,3 -dim-ethylbenzidine with the diacyl chloride of trimellitimide of p-aminobenzoic acid, or the imide formed from p-amino benzoic acid and terephthalic acid. Lyotropic behaviour was observed in cone, sulphuric acid solution [38]. A series of thermotropic poly(imide-amide)s was prepared based on trimellitimides formed from trimellitic anhydride and an a, -bis(4-aminophenoxy) alkane with carbon chain lengths 9-12. Melting points were in the range 250-300 °C. They formed smectic A phases and tended to degrade around the isotropisation temperatures (around 350 °C). Pendant methyl groups or occupied meta- groups tended to prevent mesophase formation [39]. Novel LC poly(imide-amides) have also been synthesised from new diamine spacers derived from linear diaminoalkanes and 4-nitrophthalic anhydride. A smectic and nematic phase were observed when 4,4 -biphenyl dicarboxylic acid was used as co-monomer [40]. 

All-p-phenylene oxadiazole/N-methyl hydrazide copolymers have yielded high performance fibers with tenacities of 18-21 gpd and moduli above 300 gpd through an unconventional polycondensation reaction of terephthalic acid, dimethyl terephthalate and hydrazine sulfate in fuming sulfuric acid and subsequent "reaction spinning" into aqueous acid. 

Linear strictly bifunctional oligomers of THF with molecular weights close to 1000 or 2000 and having two terminal OH groups are prepared in bulk with strong protonic acids (cf. Sect. 6.2). These oligomers are mostly used as soft segments in block copolymers made by polycondensation with diisocyanates or with 1,4-alkylene (ethylene, butylene) terephthalates. 

In recent years methods have been developed to produce terephthalic acid with satisfactory purity, and direct polycondensation reaction with ethylene glycol is now the preferred route to this polymer. 

Various organic solvents were used as reactionary medium at nonequilibrium polycondensation in solution realization [96]. The solvent type influence on the synthesis reaction main characteristics (conversion degree Q and molecular weight MM) is well known and is explained usually by solvent various characteristics (dielectric constant, solubility parameter, heat of dissolution and so on) [96]. However, up to now the indicated effects general theoretical explanation is not obtained. Besides, at the solvent type influence analysis its correlation with polycondensation process quantitative characteristics (the same Q and MM) is usually considered, but any changes of polymer structure or reaction mechanism are not assumed, although the possibility of side reactions is noted repeatedly [96]. The authors [71, 127] studied the solvent influence on the enumerated above characteristics on die example of the rules of chloranhydride of terephthalic acid and phenolfthaleine low-temperature polycondensation (polyarylate F-2), performed in 8 different solvents [128]. 

Phthalocyanines with M = Si(OH)2 or Ge(OH)2 were eovalently incorporated into polyesters during the polycondensation of terephthalic acid dimethylester and ethylene glycol [182]. With only lO" molar amounts of dye, the polyesters are intensely blue-colored. Good solubility can be achieved in water by axial substitution at the central metal or with hydrophilic polymers. Phthalocyanines with the tetravalent M = SiCb were reacted with the sodium salt of methoxypoly(oxyethylene) (M = 5000 Da) to give the blue-colored polymer 68 which is soluble in water and some organic solvents [183]. The reaction of phthalocyanines with the trivalent M = AlCl with poly-(oxyethylene) or poly(vinylalcohol) also led to water-soluble polymers having covalent bonds of the polymers at the Al(III) [184]. These water-soluble materials have been tested in the photodynamic therapy of cancer. 

Several synthetic routes are known for the synthesis of aromatic LC polyesters. Melt, solution, and slurry polycondensations are mainly used. Most significant are the polycondensation of terephthalic acid diesters and aromatic diols, the polycondensation of terephthalic acids and acetates of aromatic diols with the addition of transesterification catalysts, and the polycondensation of aromatic diols and aromatic diacid dichlorides [2]. A method successfully utilized for laboratory synhesis is the polycondensation of silated aromatic diols and aromatic diacid dichlorides [3]. Molecular weights depend significantly on the reaction conditions and on the solubility as well as the fusibility of the polyesters, which is relatively poor for para-linked unsubstituted aromatic polyesters. 

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