Interfacial polycondensation, reaction conditions

If one were to choose more reactive monomers, it would be possible to carry out polycondensations at considerably lower temperatures in solution. For example, consider the reaction of a diamine and a diacid to make a polyamide (nylon), a polymerization that requires relatively high temperatures (see Equation 9). A much faster reaction would occur between the diamine and a corresponding diacid chloride (see Equation 10). Both reactions would produce the same polymer, although the reaction conditions would be much different, and the byproduct HC1 from the acid chloride reaction would have to be carefully trapped. One technique for performing a polymerization such as that in Equation 10 is to dissolve the monomers in different, immiscible solvents, forcing the polymerization to occur only at the interface of the two solvents, a process called interfacial polymerization. Because of the high reactivity of an acid chloride, these reactions can be carried out at very low temperatures. This polymerization can be carried out rather dramatically in a beaker and is known as the nylon rope trick (see Section 4). 

Syntheses. Interfacial Polycondensation. Morgan has discussed low temperature polycondensations involving room temperature reactions of fast-reacting intermediates under interfacial conditions (II). In his many papers (9) concerning this method of polymer preparation, in the published work of Conix (I, 2, 3), and in our own patent (6), the application of interfacial polycondensation to polyphthalate and to polysulfonate preparation is well described. Hence, we dwell only briefly on the interfacial method to make available our observations particularly with regard to scaleup problems. 

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. 

Simple melt blending reactions can also be applied to preparations of block copolyamides, similarly to the process for polyesters, th time, total equilibrium conditions also are gradually achieved in the melt. Interfacial polycondensation is also useful in preparation of block copolymers. When mixed diacid chlorides and/or mixed diamines are reacted, the more active diacid chlorides and/or diamines react preferentially and blocks form. In addition, it is possible to carry out the growth of one of the segments first, to a fairly large size, and follow it by addition of the other comonomers. ... 

The PEAs reported in this work were prepared in a simple way by solution or interfacial polycondensation, where di-p-toluenesulfonic acid salts of bis-(a-amino acid)-a,co-alkylene diesters react with chlorides of dicarboxylic acids (interfacial polycondensation) or their active diesters (Active Polycondensation, APC). The APC method involves the condensation of two partners (I) bis-electrophilic, activated dicarboxylic acids, and (II) bis-nucleophilic, acid salts of bis-(a-amino acid)-a,(0-alkylene diesters in combination with di-p-toluenesulfonic acid salts of L-lysine benzyl ester. This reaction proceeds under mild conditions in common organic solvents and leads to polymer of high molecular weight (up to 300 KDa). A detailed review of the APC method has been recently summarized by Katsarava (7). 

Interfacial Polycondensation n Involves polymer formation at or near the interface between two immiscible monomer solutions under very mild reaction conditions. 

No polymer can be obtained in the absence of TBAH even after lS h of reaction at 65°C ( run 1, Table 1). Concentration ofAX) ,Q in the organic phase is very low in the absence of DCB ( 4% of TBAH in the conditions of run 2, Table 1). Thus, this type of polycondensation might be considered as a special case of an interfacial polycondensation in which the locus of the polymerization is presumably more in the organic phase than at the interface and the concentration of, Q is much lower than that of chloromethyl groups. This last point can explain that the polyethers contain chloromethyl groups at each end. 

This class of polymerization type is similar to an emulsion and suspension polymerization, however, it is mostly commonly employed for polycondensation reactions. An interfacial polymerization reaction occurs at or near the interfacial boundary of two immiscible solutions. The two reagents meet at the interface and react rapidly. The basis for this method is from the Schotten-Baumann reaction between an acid chloride and a compound containing an active hydrogen atom. Under the right conditions thin flexible walls of alternating copolymer form rapidly at the interface to form liquid-filled capsules (Scott et al, 2005. These capsules (about 210 nm) have been explored as direct and efficient encapsulation devices, given that their nanometer thick shells (about lOnm) and confined liquid-core domain, offer unique sequestration potential compared to conventional polymer nanoparticles. It has been proposed that... 

Furthermore, polycondensations of bisphenol-A and diphosgene were performed in a homogeneous phase with pyridine as catalyst and HCL acceptor. The excess of diphosgene was varied to compensate for the loss due to side reactions. After optimization of the reaction conditions the MALDl-TOF mass spectra displays again an almost exclusive formation of cyclic polycarbonates, but the highest Mn amounted only to 15 kDa. In other words, the interfacial polycondensations... 

In interfacial polymerization, the two reactants in a polycondensation meet at an interface and react rapidly. The substances used are multifunctional monomers. Generally used monomers include multifunctional isocyanates and multifunctional acid chlorides. The basis of this method is the classical Schottenn-Baumann reaction between an acid chloride and a compound containing an active hydrogen atom, such as an amine or alcohol, polyesters, polyurea, and polyurethane. Under the right conditions, thin, flexible waUs/sheU will be formed at or on the surface of the droplet or particle by polymerization of the reactive monomers. 

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