摘要:

Interfacial polycondensation came into prominence in the 1950′s with the work of Schnell on polycarbonates, Conix on polyesters, and Wittbecker, Morgan and co-workers on polyurethanes, polyamides and other polymer classes. There were a few earlier patent references. The method has several variations and is a highly effective procedure for the rapid preparation of many polymers on a small scale. It is particularly appropriate for polymers which are thermally unstable or unmeltable, for use with volatile or unstable intermediates and for polymers with reactive functional groups. Literally thousands of polymers have been made by this process. There are a number of short-comings to the process, most of which can be overcome by adjustment of the polymerization conditions. Polycarbonates and aromatic polyamides are reported to be prepared commercially by stirred interfacial processes. Another application is the encapsulation of pesticides, inks, and other materials. As to the future, the processes are a basic part of the chemist's tool kit and will continue to be used in the laboratory for rapid syntheses and for those polymers which are not obtained as readily by other means. The basic tests of commercial use of these processes, as with any other process, will be attainment of results not available by other routes, economic considerations, and safety and environmental factors.

ISSN:0022-233X    

DOI:10.1080/00222338108056761

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Since conventional model membranes (Black Lipid Membranes (BLM), liposomes) lack in long time stability, a number of polymerizable lysophospholipid and phospholipid like monomers were synthesized, where the diacetylene moiety was the polymerizable unit. The hydrophilic head groups were simple ammonium, ether, or amine structures as well as phosphorus containing groups also occurring in nature. A first characterization of the monomers was achieved by surface pressure-area diagrams at the gas-water interface. Additionally, these monolayers could be polymerized via UV irradiation yielding stable, totally rigid polymer films. The mechanism of the polyreaction was followed with a new device permitting the recording of mono-layer UV spectra. Electron microscopy showed that sonication of aqueous suspensions of phospholipid and lysophospholipid analogs yielded spherical vesicles, which could be polymerized by UV light under complete retention of their structure.

ISSN:0022-233X    

DOI:10.1080/00222338108056762

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Microencapsulation techniques have been developed to produce microcapsules of nanometer size when necessary. The control of the ratio of wall thickness to capsule diameter and the control of microcapsule diameter size have been improved. Animal digestive systems differ; e.g. Ruminants have a more complex digestive system than other animals. A microencapsulated drug orally administered will remain unaltered as it passes through the rumen and abomasum to the feces. For example, control of fecal breeding flies by retention of a microencapsulated pesticide drug into the manure has been achieved. Unsaturates may also be protected from hydrogenation and be absorbed unaltered in the abomasum by this process. Considerable attention has been given to control the rate, extent, and site of action for Pharmaceuticals. These mechanisms are discussed and some examples are given. A description of the Food and Drug Administration requirements for approval of these drug delivery systems are presented.

ISSN:0022-233X    

DOI:10.1080/00222338108056763

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Reverse osmosis membranes are currently finding increasing use in the production of potable water from salt-laden water sources, and in the purification and recycle of industrial process waters. Most reverse osmosis membranes are comprised either of polyamide hollow fibers or cellulose acetate sheet films. A new type of reverse osmosis membrane, made by the interfacial synthesis of ultrathin membranes directly on microporous support media, is being explored. Two types of interfacially formed membranes are specifically described. One is based on an ultrathin polyamide barrier layer made by interfacial reaction of polyethylenimine with isophthaloyl chloride. The barrier material is supported by a heat-polymerized intermediate zone of polyethylenimine, supported in turn by a microporous polysulfone substrate. The second membrane consists of a polyamide formed from piperazine and a mixed acyl halide reagent. This nonpolymeric amine leads to a different surface texture and the absence of an intermediate zone between the barrier film and the microporous polysulfone substrate. This latter membrane exhibits excellent water fluxes (as high as 4.0 m3/m2-day at 100 atm) under seawater reverse osmosis test conditions, and shows very high rejection (99+%) of inorganic salts containing polyvalent anions. Differences in the morphology of the salt barrier layers for these two cases are described, and the resulting effects on membrane desalination properties are discussed.

ISSN:0022-233X    

DOI:10.1080/00222338108056764

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The synthesis and structural characterization of titanium polyoximes derived from bis(cyclopentadienyl)titanium dichloride is described. Dioximes were selected for study based on geometrical dissymmetry, potential biological activity and the potential for extended conjugation through the resulting polyoxime chain. Product yield and chain length appears dependent on the electronic character of the oxime. Product chain length also appears dependent on polymer solubility. Structural characterization using elemental analyses, infrared spectroscopy, light scattering photometry, control reactions and coupled thermogravimetric-mass spectroscopy is described.

ISSN:0022-233X    

DOI:10.1080/00222338108056765

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The synthesis of titanium polydyes emphasizing the inter-facial technique is described. Emphasis is placed on applications of the polydyes taking advantage of the potential permanent, nonleaching nature of such materials compared with the monomeric dyes themselves. The polydyes are fluorescent and can be impregnated into paper, cloth and paint and “doped” into plastics giving fluorescent materials.

ISSN:0022-233X    

DOI:10.1080/00222338108056766

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Interfacial polycondensation reactions are routinely conducted with empirically developed methodology which might be improved if some well-known principles of colloid and surface chemistry were invoked. An example in the interfacial synthesis of polymers is the use of additives such as catalysts and emulsifiers to enhance the degree of polymerization. In this paper possible modes of action of surfactants and quaternary ammonium catalysts in stirred interfacial polycondensation are examined. The agents are considered variously as ions, molecules, and micellar aggregates, acting upon each component of the system, i.e. monomers, oligomers, polymers, and solvents. The functions delineated include emulsification of the solvent phases, solubilization of monomers in regular or inverse micelles, solubilization of oligomers and polymers, phase transfer catalysis, and micellar catalysis.

ISSN:0022-233X    

DOI:10.1080/00222338108056767

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The polycondensation of terephthaloyl chloride and bisphenol A was used as a model reaction for the production of linear aromatic polyesters in stirred interfacial polymerization. The evaluation of several catalytic and surfactant additives to this system was based upon yields and intrinsic viscosities of the products obtained with both low and high concentrations of cationic surfactants of the quaternary ammonium type, of an anionic surfactant, and of a non-micelle forming quaternary ammonium salt. Although yields were similar in most cases, viscosity differences were marked. The highest intrinsic viscosities, hence highest degrees of polymerization, were found for preparations where cationic surfactant in excess of the critical micelle concentration was employed. Modes of action for such surfactants are suggested. The possibilities include, but are not limited to, solubilization of the product, solubilization of either or both monomers, emulsification of the liquid phases, catalytic phase transfer of one monomer, and micellar catalysis.

ISSN:0022-233X    

DOI:10.1080/00222338108056768

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Previous attempts to prepare copolymers by the reaction of vinyl monomers, such as styrene, with “trapped free radicals” such as acrylonitrile macroradicles has been unsuccessful because of the large differences in solubility parameters between the liquid and the solid. However, acrylonitrile will react with styrene macroradicals in the absence of oxygen, and yield block copolymers. Block copolymers may be produced from other vinyl monomers and other macroradicals when the difference in the solubility parameter of the monomer and macroradicals is less than 3.2H.

ISSN:0022-233X    

DOI:10.1080/00222338108056769

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

N-Methylated polyamides and copolyamides derived from sebacic acid, N,N′-dimethylethylenediamine, and ethylenediamine were synthesized. Both interfacial polycondensation and melt poly-condensation were examined, with the interfacial generally giving the higher molecular weights. The choice of organic solvent was important in the copolyamide synthesis with hexane giving random copolyamides and the more polar chloroform yielding copolyamides with a more blocklike structure, comparable to that obtained from the melt. The softening point of the N-methylated poly-amide was between 65-75°C.

ISSN:0022-233X    

DOI:10.1080/00222338108056770

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor