Bulk polycondensation

The bulk polycondensation of (10) is normally carried out in evacuated, sealed vessels such as glass ampules or stainless steel Parr reactors, at temperatures between 160 and 220°C for 2—12 d (67). Two monomers with different substituents on each can be cocondensed to yield random copolymers. The by-product sdyl ether is readily removed under reduced pressure, and the polymer purified by precipitation from appropriate solvents. Catalysis of the polycondensation of (10) by phenoxide ion in particular, as well as by other species, has been reported to bring about complete polymerisation in 24—48 h at 150°C (68). Catalysis of the polycondensation of phosphoranimines that are similar to (10), but which yield P—O-substituted polymers (1), has also been described and appears promising for the synthesis of (1) with controlled stmctures (69,70). 

Poly(poly(alkylene terephthalate)-Woc -poly(oxyalkylene)) thermoplastic elastomers are prepared by the bulk polycondensation of dimethyl terephthalate with a mixture of 1,4-alkanediol and hydroxy-terminated poly(oxyalkylene) in... 

This aliphatic hyperbranched polyester is prepared by the bulk polycondensation of 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) as AB2 monomer and 1,1,1-tris(hydroxymethyl)propane (TMP) as B3 core molecule, according to a procedure... 

The DB obtainable in SCVP is DB=0.465 for r=kjk =l and reaches its maximum, DB=0.5, for r=2.6 [70,78]. This value is identical to that obtained in AB2 polycondensation when both B functions have the same reactivity [70,78]. Thus, hyperbranched polymers prepared by bulk polycondensation or polymerization contain at least 50% linear units, making this approach less efficient than the synthesis of dendrimers. 

Monomers 1 and 2 were also used as comonomers with dimethyl dialkanoates and monomers containing furan rings, for the synthesis of copolyesters by bulk polycondensations, in the presence of titanium isopropoxide or tetra-butyl-1,3-dichloro-distannoxane. In general, the biodegradability of the copolyesters of 1 decreased with increasing difuran dicarboxylate content, and copolymers... 

Imbalance in the stoichiometry of polycondensation reactions of AA-BB-type monomers can be overcome by changing to heterofunctional AB-type monomers. Indeed, IIMU has been subjected to bulk polycondensation using lipases as catalyst in the presence of 4 A molecular sieves. At 70 °C, CALB showed 84% monomer conversion and a low molecular weight polymer (Mn 1.1 kDa, PDI 1.9). No significant polymerization was observed with other lipases (except R cepacia lipase, 47% conversion, oligomers only) and in reference reactions with thermally deactivated CALB or in the absence of enzyme. Further optimization of the reaction conditions (60wt% CALB, II0°C, 3 days, 4 A molecular sieves) gave a polymer with Mn of 14.8 kDa (PDI 2.3) in 86% yield after precipitation [42]. 

The rotating-disk reactor is applicable for bulk polycondensation reactions such as those for the productions of Nylon 66 and 610, polyethylene terephthalate, polyurea, and polycarbonate. High agitation and multidisks provide a high rate of surface renewal, which increases the efficiency of the reaction process. 

Incidentally, bulk polymerization is also the chief method used for commercial polycondensations. Polycondensations are not as exothermic as free radical catalyzed vinyl-type polymerizations, so thermal control is less of a problem. Bulk polycondensation also favors formation of linear polymer rather than the cyclic products that are favored by dilute solution polymerization, particularly if AB-type monomers are being used. Finally, since a high degree of polymerization (i.e., high DP, or high molecular weight) is only... 

Dimethyl terephthalate or Bulk polycondensation Apparel (61%), home... 

Phthalic anhydride, maleic anhydride, fumaric acid, isophthalic acid, ethylene glycol, propylene glycol, diethylene glycol, styrene Bulk polycondensation followed by free-radical-initiated chain polymerization Construction, automotive applications, marine applications... 

Adipic acid, hexamethylenediamine, caprolactam Bulk polycondensation Home furnishings, apparel, tire cord... 

The techniques employed to make the fluorescent pigments have varied over the years. The original method used was the bulk polycondensation reaction of melamine, formaldehyde, and toluene sulfonamide. The resulting products were tailored to various applications by being thermoplastic or thermoset depending upon the mole ratios of the polymefs raw materials. 

FIGURE 8.2 Synthesis of poly(ester amide)s from sucdnic anhydride and a,co-amino alcohols by solution polycondensation. iV-(hydroxyalkyl) imide by-prcxlucts were on the contrary obtained by bulk polycondensation. 

FIGURE 8.3 Synthesis of regular PEAs by a bulk polycondensation method based on the formation of metal halide salts. Derivatives of to-amino acids and glycolic acid (a) and diamines, dicarboxylic acids, and glycolic acid (b). 

The monomers used in the production of these materials are adipic acid, hexamethylenediamine and caprolactam. Polymerization is traditionally done via bulk polycondensation. The commercial success of nylon-6 and nylon-6,6 is due to outstanding properties and an economically attractive raw material base. Nylon-6,6 is produced by melt condensation of adipic acid with hexamethylenediamine. Both... 

A highly activated AB2-monomer is 3,5-bis(trimethylsiloxy) benzoyl chloride (3-3) that leads to a high DB of 60% in a bulk polycondensation, as the once-reacted monomer is activated for the second condensation step the DB was increased to 64% by slow monomer addition to trimethylolpropane (2-(hydroxymethyl)-2-ethylpropane-f,3-diol) (TMP) as a core molecule. As mentioned above, 2,2-bis(hydroxymethyl) propanoic add (bisMPA) (3-6) is a major monomer for aliphatic hb polyesters (Boltom) but shows cydization and other side reactions (e.g., etherification) during polycondensation. A comparable easy-to-handle monomer is bis(4-hydroxyphenyl) pentanoic acid that can be easily polycondensed in the melt or solution, leading to polyesters with a DB of 50% and with only a low tendency for side reartions. Smet et al. presented highly branched copolyesters by a combination of AB2-polycondensa-tion and the ROP of -caprolactone. ... 

Okada et al. have worked extensively on biodegradable polymers based on dianhydroalditols as carbohydrate renewable resources. A series of polyesters were synthesized by the bulk polycondensation of the respective three stereoisomeric dianhydroalditols (DAS, DAM, and DAI) with aliphatic dicarboxyUc acid dichlorides of 2-10 methylene groups [21, 22]. It was found that the biodegradability of the polyesters varied significantly depending on their molecular structures. 

Poly(ester carbonate)s with different compositions were synthesized by bulk polycondensation of DAS with diphenyl sebacate and diphenyl carbonate in the presence of zinc acetate as a catalyst [27]. Biodegradability was found to be highest for the poly(ester carbonate)s with carbonate contents of 10-20 mol per cent, and to decrease markedly for those with the carbonate content above 50 mol per cent. 

Following the success of the solution polycondensation, bulk polycondensation of L-lactic acid was studied to eliminate the use of solvent. 

If ricinoleic acid is the actual AB monomer, self-polycondensation leads to the corresponding polyester nsing conventional and enzymatic polyesterification catalysts [9, 10, 18] (Scheme 3.8). Ebata and co-workers [9] studied lipase-based bulk polycondensations applied to the methyl ester so that they could study this polymerisation in detail under green-chemistry conditions. The molecular weight of the ensuing polyesters was 2-100 kDa depending on the enzyme used, and the best results were obtained with lipase from Pseudomonas cepacia. 

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. 

Takasu et al. [24] reported that scandium trifluoromethanesulfonate [Sc(OTQ3] and scandium trifluoromethanesulfonimide [Sc(NTf2)s] are effective for one-step dehydration polycondensation of L-lactic acid. Bulk polycondensation of L-lactic acid was carried out at 130-170°C to give PLLA with Mn of 5.1 xlO -7.3xl0 (yield 32%-60%). However, the solution polycondensation was... 

PBAT can be synthesized by conventional bulk polycondensation techniques. It degrades completely in soil, in aqueous environment, and under composting and anaerobic conditions within varying time periods, depending on the average chain length of the aromatic blocks [108-111], Table 7.4 lists the properties of... 

---