Composite reverse osmosis and nanofiltration membranes

Membranes with unprecedented solvent permeance and high retention of dissolved solutes are needed to reduce the energy consumed by separations in organic liquids We used controlled interfacial polymerization to form free-standing polyamide nanofilms less than 10 nanometers in thickness, and incorporated them as separating layers in composite membranes Manipulation of nanofilm morphology by control of interfacial reaction conditions enabled the creation of smooth or crumpled textures; the nanofilms were sufficiently rigid that the crumpled textures could withstand pressurized filtration, resulting in increased permeable area Composite membranes comprising crumpled nanofilms on alumina supports provided high retention of solutes, with acetonitrile permeances up to 112 liters per square meter per hour per bar This is more than two orders of magnitude higher than permeances of commercially available membranes with equivalent solute retention

http://science.sciencemag.org/content/sci/348/6241/1347.full.pdf

Sub–10 nm polyamide nanofilms with ultrafast solvent transport for molecular separation

The emergence of Turing structures is of fundamental importance, and designing these structures and developing their applications have practical effects in chemistry and biology. We use a facile route based on interfacial polymerization to generate Turing-type polyamide membranes for water purification. Manipulation of shapes by control of reaction conditions enabled the creation of membranes with bubble or tube structures. These membranes exhibit excellent water-salt separation performance that surpasses the upper-bound line of traditional desalination membranes. Furthermore, we show the existence of high water permeability sites in the Turing structures, where water transport through the membranes is enhanced.

Polyamide membranes with nanoscale Turing structures for water purification

A recent progress in thin film composite membrane: A review

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

Condensation polymers: by interfacial and solution methods

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. This 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 102–104 1. 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 monofunctional reactants, detergents, and salts. The formation of polyphenyl esters is discussed briefly.

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

Synthese en solution et a l'etat fondu. Attention particuliere au polymere derive du terephtaldehyde et de la methylphenylenediamine-1,4

Aromatic azomethine polymers and fibers

Interfacial polycondensation is a rapid, irreversible polymerization at the interface between water containing one difunctional intermediate and an inert immiscible organic solvent containing a complementary difunctional reactant. It is based on the Schotten-Baumann reaction in which acid chlorides are reacted with compounds containing active hydrogen atoms (—OH, —NH and —SH). A large number of polymers (heat-sensitive and infusible as well as stable and meltable) can be prepared. The method has been applied to the preparation of polyurethanes, polyamides, polyureas, polysulfonamides, and polyphenyl esters. Interfacial polycondensations are run in simple, open laboratory equipment with or without stirring. With suitable agitation granular or powdered polymers with high molecular weight are prepared at room temperature and isolated within a few minutes. The intermediates need not be absolutely pure or in balance nor is a quantitative yield needed in order to obtain high polymer. The major variables in the interfacial polycondensation process are discussed and the laboratory techniques and principles are contrasted with melt polycondensation.

Interfacial polycondensation. I.

Fibers of high molecular weight p-oriented polycarbonamides of recurring units of the formula: WHEREIN Ar1 is p-phenylene and/or chloro-substituted pphenylene, and Ar2 is p-phenylene. These fibers have an initial modulus in excess of 170 gpd. and an orientation angle of up to 40* and/or a sonic velocity of at least about 4 km./sec. either as-extruded or after maintaining the fibers at 0.99 to 1.50 times their as-spun lengths and heating in a zone maintained between 200* and 1,000* C. Optically anisotropic spinning dopes of these polycarbonamides of Formula I units, lithium or calcium chloride and certain amide or urea solvents, are also disclosed.

Paul W. Morgan

Papers

Condensation polymers: by interfacial and solution methods

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

Aromatic azomethine polymers and fibers

Interfacial polycondensation. I.

Optically anisotropic spinning dopes of polycarbonamides