Thermal polycondensation

The second step is the thermal conversion of borylaminoborazine into poly(borylaminoborazine). Continuous elimination of parent alkylamine is the main by-product dining the thermal polycondensation of 2,4,6-trialkylaminoborazine (see earlier). We expected the continuous elimination of the starting 5-alkylam i noborane during the thermal polycondensation of borylborazine. However, the alkylami noborane is a liquid, which requires that the thermal polycondensation must be performed in vacuo to continuously remove the evolving B(NHR)3 from the reaction mixture. This procedure also precludes any competing polycondensation reaction from B(NHR)3. 

It is probable that other types of linking are present in the proteinoids reactive molecular fragments lead to more complex compounds such as heterocycles (Heinz et al., 1979). Under other conditions (temperatures above 458 K), pteridines and flavines can be detected. The thermal polycondensation of lysine, alanine and glycine (458 K, 5 h) gave a "chromo-protenoid the chromophores identified were flavines (a) and diazoflavines (b) (Heinz and Ried, 1984). 

CycUc polyamides were reported to be isolated from Nylon 6 polymers in 1956 [18,19]. Thermal polycondensation of co-amino acid (carbon number > 6) gave a cycUc and linear polymer [82]. Moreover, upon heating polyamide in the presence of a transamidation catalyst, the cyclization equilibrium is eventually reached, and both Unear and cyclic constituents are present [83]. The proportion of the latter depends on the concentration, and cycUc compounds predominate in high dilute solutions. 

Synthesis ofOligof 1,3-Propylene Succinate)s by Thermal Polycondensation... 

Different a,co-dihydroxy-terminated oligo(propylene succinate)s (SP) were prepared by the thermal polycondensation of excess 1,3-propanediol and succinic acid, as illustrated in the first part of Scheme 9 [4]. The molar ratio of 1,3-propanediol to succinic acid was maintained in the range of 1.05-1.25. The molecular weight of the products depended on the excess 1,3-propanediol used, but it usually ranged between 900 and 2400. The molecular characterization and appearance of some typical samples are given in Table 2. 

Scheme 9. Synthesis of oligo(propylene succinate), by thermal polycondensation of 1,3-propanediol and succinic acid, and chain-extension reaction by diisocyanate synthesis...

Later in 1967, an attempt was made to synthesize aromatic polyimide by the thermal polycondensation of the salt monomer derived from bis(4-aminophe-nyl) ether and pyromellitic acid half diester (Eq. 3, RMsopropyl) [8]. 

Recently Russian workers reported the kinetic and thermodynamic characteristics of thermal polycondensation of the salt monomers derived from some diamines and benzophenonetetracarboxylic acid half dimethyl ester leading directly to polyimides from the viewpoint of the preparation of polyimide-based advanced composite materials (Eq. 4, R =methyl) [9-12]. 

Solid-State Thermal Polycondensation of Salt Monomers... 

In short, the microwave energy was successfully applied for the first time for the rapid synthesis of condensation polymers such as polyimides and polyamides from the salt monomers (and co-amino acids) by using a simple domestic microwave oven. The rapid polymer formation is caused by the efficient internal heating of the reactants. This compares favorably with the long reaction time required for the conventional thermal polycondensation with external heating. 

The salt monomer method was successfully applied to the preparation of the electrically-conducting polyimide-carbon black composites [62]. The composites are prepared as follows An aqueous solution of salt monomer 9PMA was mixed with carbon black, giving a suspension. This was evaporated to dryness under reduced pressure to afford a homogeneously-mixed powder composed of the salt monomer and carbon black. The powder was subjected to solid-state thermal polycondensation in the form of a pellet at 240 °C for 1 h under atmospheric pressure. The semiconducting aliphatic polyimides (P-9PM, Tm=315 °C) having electric conductivity of about 10"6 S/cm was readily obtained by mixing only 1 wt% of carbon black based on the polyimide. 

Then product II is subjected to thermal polycondensation and transforms into polynonylsiloxane, mostly with ladder structure. 

Black polymers of the type 49 (8) were obtained by thermal polycondensation reactions of trisally 1-dinickel-//-1,3-diborolyl triple-decker or its hexadiene-allyl-dinickel-//-l,3-diborolyl isomer 47 (50), and 50 was... 

Kokufuta, E., Suzuki, S. and Harada, K., 1977. Potentiometric titration behavior of poly-aspartic acid prepared by thermal polycondensation. BioSystems, 9 211 -214. 

Heating aspartic acid (I) with or without catalyst leads to a linear thermal polycondensation polymer known as polysuccinimide (II), conversions of monomer to polymer of greater than 95% being easily accomplished. Hydrolysis of polysuccinimide with base such as sodium hydroxide, leads to a random copolymer of a and aspartate units (III), with the 8 aspartate comprising about 70%—75% of the repeating units. 

It is well known that thermal polycondensation of ha-logenoacetates leads to polyglycolide through the elimination of a metal halide salt, which can be considered as the driving force of the polycondensation reaction. The method has recently applied to get PEAs constituted by an alternating sequence of glycolic acid and co-amino acid units (Figure 8.3a) [20-24]. Monomers be easily synthesized by the reaction of chloroacetyl chloride with the appropriated (o-amino acid and by a subsequent neutralization with a... 

As mentioned earlier, CABE prepolymers are synthesized via a simple thermal polycondensation process by reacting citric acid with diol monomers (Figure 16.2 and Table 16.1). Citric acid confers CABEs with pendent functionality for postmodification or concurrent modification and cross-linking. While the elasticity of CABEs mostly depends on the chain length of the diol used, if... 

By introducing quaternary anunonium salt diol into POC, Wynne et al. conferred antibacterial properties to the resulting POC-Q through a convenient and cost-effective thermal polycondensation process [42]. These materials have a tailored surface and strong antibacterial properties that make them good candidates as biodegradable packaging materials. 

Polyol monomer like xylitol was also used to compose biodegradable polymer poly(xylitol citrate) (PXC) with citric acid by a simple thermal polycondensation. The abundant pendent hydroxyl groups on PXC, mostly introduced by xylitol, were used to react with methacrylic anhydride to obtain double bond functional PXC (PXCma), which can be formed into a bioelastomer network by photo-cross-linking [96]. 

PN. Coneski, PA. Fulmer, J.H. Wynne, Thermal polycondensation of poly(diol dtrate)s with tethered quaternary ammonium biocides, RSC Adv. 2 (2012) 12824-12834. 

Fig. 2.2 Scheme illustrating the synthesis of polyfglycerol sebacate) through thermal polycondensation. Adapted from Ref. [7]... 

PGS is a bioresorbable elastomeric polymer and extensively evaluated for various biomedical applications such as soft and hard tissue engineering and controlled drug delivery [8]. In a similar way, a number of aliphatic polyester elastomers for various biomedical applications were prepared from diacid monomers such as citric acid and a-ketoglutaric acid with aliphatic diols and triols using thermal polycondensation reactions [9-12]. 

Fig. 2.5 Scheme illustrating the synthesis of polyesteramide following thermal polycondensation. 

Nanocomposites of organomodified montmorillonites (C20A, C25A, and C30B) and a biodegradable PEA were obtained by in-situ polycondensation of sodium chloroacetylaminohexanoate [75]. This synthesis was based on a thermal polycondensation reaction in which the formation of a metal halide salt became the driving force of the process [76, 77]. 

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