Interfacial polycondensation. II. Fundamentals of polymer formation at liquid interfaces

Abstract

If a solution of a fast‐reacting diacid halide in a water‐immiscible solvent is brought together with an aqueous solution of a diamine without stirring, a thin film of high polymer is formed at once at the interface. Polyurethanes and polyamides in. particular form tough films which can be grasped and pulled continuously from the interface as a folded rope of film. The unstirred interfacial polycondensation not only provides a dramatic demonstration of polymer formation but has permitted the observation of polymerization behavior and the study of the effects of many variables upon the process. The polymer‐forming reactions proceed by nucleophilic displacement, and many have rate constants of at least 102–101 l. mole‐1 sec.‐1. Polymers derived from diamines were found to form in the organic solvent phase. Therefore the rate of polymer formation is controlled by the transfer of diamine from the aqueous phase. It is believed that the liquid interface does not have any beneficial orienting effect on the reactants but that it provides for the regulated flow of one reactant into an excess of the other. Furthermore, the aqueous phase provides for the removal of the interfering byproduct, hydrogen halide, from the polymerization site. Some of the interrelated variables which have been studied and which are discussed in relation to the physical mechanism are the solvent sensitivity of the polymer, partition coefficients of the reactants, reactant concentration, duration of the polymerization, and the addition of the monofunctional reactants, detergents, and salts. The formation of polyphenyl esters is discussed briefly.

Impacts of reaction and curing conditions on polyamide composite reverse osmosis membrane properties

“…Therefore, it is common to use a large excess of amine over acid chloride (typically about 20:1), which drives partitioning and diffusion of the amine into the organic phase. Any factors that alter the solubility and diffusivity of the amine monomer in the organic phase affect the reaction rate, and thus, the morphology and structure of the resulting polyamide film, which ultimately define separation performance and interfacial properties [8,9].…”

“…When the two monomer solutions are brought into contact, both monomers partition across the liquid-liquid interface and react to form a polymer; however, polymerization occurs predominantly in the organic phase due to the relatively low solubility of most acid chlorides in water [6][7][8]. Therefore, it is common to use a large excess of amine over acid chloride (typically about 20:1), which drives partitioning and diffusion of the amine into the organic phase.…”

“…Laboratory set up for evaluating RO membrane separation performance-(1) N 2 cylinder, (2) gas regulator, (3) pressure gauge, (4) pressure releasing valve, (5) feed tank, (6) membrane test cell, (7) magnetic stirrer,(8) permeate collector, and (9) weighing balance.…”

Influence of heat-treatment on CO2 separation performance of novel fixed carrier composite membranes prepared by interfacial polymerization

“…Since the conception of IP was put forward by Morgan and Kwolek [21], interfacial polymerization or polycondensation has become a well-established synthesis method for the preparation of thin films. Membrane preparation is one among the most successful applications of the IP technique and commercially thin-film composite (TFC) reverse osmosis (RO) membranes and TFC nanofiltration (NF) membranes were manufactured by IP process.…”

Nanofiltration across Defect-Sealed Nanoporous Monolayer Graphene

“…21,22 Due to the solubility of hexamethylenediamine in the organic phase, nylon 6,6 forms within the organic phase where the mass fluxes of the two monomers result in the correct stoichiometry. 22 Since the PCTE membrane pores are wetted by the organic phase, we expect nylon 6,6 to deposit within the PCTE pores behind large graphene defects that are not sealed using ALD (Fig. 3).…”