Low temperature solution polycondensation

The first low-temperature solution processable PAs from acid chlorides were carried out in halogenated hydrocarbons. Piperazines and aliphatic or aromatic diacid based polymers were the first attempted pol)rmers. Now this is not a preferred route to synthesize wholly aromatic PAs [16]. The solvents used are polar aprotic solvents like N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), hexamethyl phosphoramide 

The polycondensation reaction can also be carried out in a two-phase system at room temperature, via the so-called interfacial polymerization [18]. The diamine and the acid dichloride monomers are dissolved in water and a water-immiscible solvent, respectively. A base and a surfactant are generally added to the aqueous media. The mixture of immiscible solutions, upon rapid stirring, gives rise 

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High-molecular-weight fluorine-containing aromatic poly(benzoxazole)s have not been obtained either by the direct solution polycondensation in PPA at 200°C or by the low-temperature solution polycondensation in DMAc at 0 to 5°C from 2,2-bis(3-amino-4-hydroxyphenyl)-l,l,l,3,3,3-hexafluoropropane and aromatic diacid derivatives because the fluorine-containing monomer has low nucleophilicity owing to the presence of the electron-withdrawing hexafluoroiso-propylidene unit. 

Mamyama et al.25 have obtained high-molecular-weight poly(benzoxazole)s by the low-temperature solution polycondensation of A,A 0,0 -tetrais(trimethyl-silyl)-substituted 2,2-bis(3-amino-4-hydroxyphenyl)-l,l,l,3,3,3-hexafluoro-propane (25) with aromatic diacids and subsequent thermal cyclodehydration of the resulting poly(o-hydroxy amide)s in vacuo. In this method, aromatic diamines with low nucleophilicity are activated more positively through the conversion to the /V-silylated diamines, and the nucleophilicity of the fluorine-containing bis(o-aminophenol) can be improved by silylation. 

Polyethers and polyesters having methoxybenzalazine units with various alkylene groups (C4, C6 and Cg) in the main chain were synthesized from vanillin (7,8). The condensation reaction of 4,4 -alkylenedioxybis (3-methoxybenzaldehyde) [VI] with hydrazine monohydrate was applied to the synthesis of polyethers [VII] (Mn, 7.4 x 103 for C4, 7.3 x 103 for C6 and 4.1 x 103 for Cg derivatives), as shown in Scheme 3. Polyesters [IX] (77jnh, 0.35 dl/g for C4, 0.38 dl/g for C6 and 0.43 dl/g for Cg derivatives) were synthesized from 4,4 -dihydroxy-3,3 -dimethoxybenzalazine [VIII] and di-carboxylic acid chlorides by conventional low temperature solution polycondensation, as shown in Scheme 4. 

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, poly esterification of XI with terephthaloyl, isophthaloyl and sebacoyl chloride were carried out by the low temperature solution polycondensation and by the interfacial polycondensation. The polyterephthalate with jjinh = 1.42 dl/g was obtained by the interfacial poly condensation. The polyisophtha-late with f7 nh = 0.73 dl/g and the polysebacate with Jj nh = 0.43 dl/g were obtained by the low temperature solution polycondensation. 

Low-temperature solution polycondensation in NMP, followed by catalytic imidisation of the polyamic acids formed in reaction solutions using a pyridine-acetic anhydride (1 1) complex as catalyst (procedure 1) ... 

Step-growth polymerizations at high temperatures produce nearly random copolymers because of end-group interchange reactions like (5-14) between macromolecules. Interfacial and low-temperature solution polycondensations are conducted under essentially irreversible conditions, by contrast. In these cases the average copolymer composition and blocklike character of the product may depend on the reaction conditions and relative reactivity of the functional groups involved in the polymerization. 

Trimethylsylil-substituted amines undeigo a variety of reactions with electrophiles. This reaction was extended recently to preparations of high molecular weight aromatic polyamides by low temperature solution polycondensation. N-trimethylsilylated aromatic diamines were condensed with aromatic diacid chlorides at -10 T in an amide solvent ... 

Maruyamaera/. have obtained high-molecular-weight poly(benzoxazole)s by the low-temperature solution polycondensation of A/Al 0,0 -tetrais(trimethyl-silyl)-substituted 2,2-bis(3 -amino-4-hydroxy phenyl)-1,1,1,3,3,3-hexafluoro-... 

Moigan, P.W., and S.L. Kwolek. 1964. Low temperature solution polycondensation of piperazine polyamides. Journal of Polymer Science Part A General Pcpers 2(1) 181-208. 

The first low-temperature solution polymerization of PAs from acid chlorides was carried out in halo-genated hydrocarbons. Some of the first polymers were based on piperazines and aliphatic or aromatic diacid. Tertiary amines were used as acid acceptors. Low-temperature solution polycondensation is considered a convenient method for the synthesis of PAs (Scheme 4.1). It involves low-temperature reaction... 

PBOs are generally prepared by three general methods. The first method is a two-stage polymerization (Figure 5.23) that involves a low-temperature solution polycondensation of bis(o-aminophenol)s... 

Maruyama et al. prepared a series of novel fluorinated poly(o-hydroxy amides) of high molecular weights (Mw = 3100 and M =2100g/ mol) by the low-temperature solution polycondensation of tri-methylsilyl substituted 2,2-bis... 

Hsiao et al. prepared a series of fluorinated PHAs by low-temperature solution polycondensation of 4,4 -[isopropylidenebis( 1,4-phenylene)dioxy]diben-zoyl chloride and 4,4 -piexafluoroisopropylidenebis (l,4-phenylene)dioxy]dibenzoyl chloride with three... 

A 1965 book (21) discusses low temperature solution polycondensation at length, although it does not deal with the reaction of aromatic diamines with aromatic diacid chlorides by this method. The book also discusses interfacial polymerization. 

Low-temperature solution polycondensations of a series of soluble aromatic polyamides, subjected to thermal cyclization to convert them to the corresponding polybenzothiazoles, were reported starting with 2,5-bis [(methoxycajbonyl)ethyl]thio -l,4-phenylenediamine with aromatic diacid chlorides [38-40]. The introduction of bulky and polar pendant groups in the polyamides improved the solubility of the precursor in organic solvents. 

Monomers derived from trimellitic anhydride, mainly V-carboxyphenyltrimel-litimides and V-(co-carboxyalkylene)trimellitimides have been also used many times as starting materials for the synthesis of poly (amide imide)s. These poly (amide imide)s have been traditionally prepared by low temperature solution polycondensation, from diamines and imide-diacid chlorides [182], but they have been also successfully synthesized by the phosphorylation method of direct polyamidation [184], from diamines and imide-diacids [185-188] as depicted in Scheme (36). Trimellitic acid imide (4-carboxyphthal-imide) has also been used for the preparation of poly(amide imide)s, by reaction with aliphatic and aromatic diamines in solution at moderate temperatures [189]. 

Poly(amic acid)s (PAA) were prepared by low-temperature solution polycondensation of DA-TPM and the corresponding dianhydride (25 wt % of solids). A stoichiometric amount of the solid dianhydride was added to the diamine solution in NMP at 0°C. The continuously stirred mixture was gradually heated to room temperature and allowed to stir for another 4-5 h. 

The same research group [90] reported the preparation of OA (PAIs) derived from N,N-(4,4 -oxydiphthaloyl)-bis-(s)-(+)-valine diacid chloride. The polymers were prepared by the reaction of aromatic diamines with the diacid by classical low-temperature solution polycondensation (reaction time 2 h at -5°C and 8 h at rt), high-temperature polycondensation (reflux conditions, reaction time Imin), and MW polycondensation reaction (reaction time 6min). Comparable results were obtained for all polycondensation processes. 

Poly(l,4-benzamide) (I, PBA) is most commonly prepared by low-temperature solution polycondensation of 4-aminobenzoyl chloride hydrochloride. Poly(l,4-phenylene terephthalamide) (II, PPTA), which is the aramid that has become of prime commercial importance, t5 ically is s)mthesized by solution polycondensation of terephthaloyl chloride and 1,4-phenylene diamine (1-3 see also references 4 and 5 for excellent reviews of the polymerization and processing of aramids). 

The PAS was synthesized by low-temperature solution polycondensation through a two-step procedure according the method developed by Imai et al. with a little modification [19] (Scheme 1). First, a,(o-dichloroformyl-terminated aramid oligomers were prepared by the reaction of IPC with 3,4 -DAPE in a chloroform-TEA-HCl system at — 150°C for 1 h. The reaction was then continued at room temperature for another 48 h under nitrogen. The polymer was precipitated by pouring the reaction mixture into methanol. After the product was washed successively with excess amounts of methanol, a low molecular weight fraction enriched in PDMS was removed by washing the product with n-hexane three times, then dried at 60°C for 48 h under vacuum. PAS films for surface analysis and platelet adhesion were cast from 10 wt% A, 7V -dimethylacetamide (DMAc) solution in stainless steel petri dishes. 

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