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Interfacial Polycondensation (interfacial + polycondensation)
Selected AbstractsPolyamides nanocapsules: Modeling and wall thickness estimationAICHE JOURNAL, Issue 6 2006K. Bouchemal Abstract This work provides a better understanding for effective control of the nanocapsules wall thickness. Polyamides based nanocapsules are prepared by interfacial polymerization combined with spontaneous emulsification. A clear guideline of how factors such as monomer concentration, diffusion, interfacial reaction, or water swelling influence the capsule formation is very important to the control of capsule wall structure and release performance. In this goal, the macroscopic planar models of the interfacial polycondensation between diethylenetriamine and sebacoyle chloride are studied experimentally and theoretically. This planar model is developed to examine the kinetics of the reaction and to perform the estimation of parameters thanks to the experiment measurements. The effect of the operating conditions on the wall thickness is also studied. The model is shown to be consistent with the experimental data. Next, the spherical model is deduced from the first one. The results obtained with this model are in accordance with some observations of wall thickness. From this model, the increase of the wall thickness is predicted for several operating conditions. © 2006 American Institute of Chemical Engineers AIChE J, 2006 [source] Enlarging the library of poly-(L -lysine citramide) polyelectrolytic drug carriersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2001Anne-Claude Couffin-Hoarau Abstract Poly-(L -lysine citramide) is a degradable drug carrier of the polyelectrolyte type that is composed of citric acid and L -lysine building blocks. In a previous work, poly-(L -lysine citramide) was synthesized by the interfacial polycondensation of ,-hydroxy acid protected citryl dichloride with COOH-protected lysine diamine. Because of head-to-head and head-to-tail and tail-to-tail linkages in the chains as well as various side reactions such as deprotection of the ,-hydroxy acid moieties and intramolecular imide ring formation, a very large family of degradable polyelectrolyte copolymers was obtained. All the members of this family hydrolytically degrade to the same end products. In this study, another route was explored based on the polycondensation of ,-hydroxy acid protected citric acid pentafluorophenyl diesters, namely, citrobenzal dipentafluorophenyl and citrochloral dipentafluorophenyl with N - N,-trimethylsilylated COOH-protected L -lysine. The resulting polymers were characterized by IR, NMR, and size exclusion chromatographic analyses. The resulting chain structures and repeat units were identified from these characterizations and are discussed as compared with characteristics exhibited by analogous polymers resulting from interfacial polycondensation. Differences observed at the intermediate stage involving protected polymers were largely erased during the final deprotection stage because of imide formation during final hydrolysis under the selected conditions. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3475,3484, 2001 [source] Synthesis of exfoliated polyamide 6,6/organically modified montmorillonite nanocomposites by in situ interfacial polymerizationPOLYMER COMPOSITES, Issue 6 2007M. Tarameshlou Polyamide 6,6 (PA 6,6)/organically modified montmorillonite (OMMT) nanocomposites were prepared by a novel method, using direct interfacial polymerization of an aqueous hexamethylene diamine and a nonaqueous adipoyl chloride in dichloromethane solution containing different amounts of OMMT dispersed nanoparticles. The state of dispersion of OMMT in the PA 6,6 matrix was investigated by means of X-ray diffraction, as well as transmission electronic microscopy. The results indicated that the OMMT nanoparticles were dispersed homogeneously and nearly exfoliated in the PA 6,6 matrix. The random arrangement of clay platelets in the PA 6,6 matrix, exfoliation, and intercalation of clays between the PA 6,6 matrix were distinguished. The amount of the incorporated OMMT in the PA 6,6 matrix was determined by means of TGA technique. Furthermore it was found that addition of a small amount of OMMT dramatically improved the thermal stability of PA 6,6. The TGA thermograms of all the synthesized nanocomposite samples showed an interesting unexpected lag in the weight loss at high temperatures, which could be another evidence for formation of fully exfoliated nanocomposites structures, with improved thermal stability. Nucleating effect of the OMMT nanoparticles and their influence on crystallization behavior of PA 6,6 was confirmed by DSC. Finally it is concluded that the in situ interfacial polycondensation is a suitable method for synthesis of nanocomposites with well dispersed structures and enhanced properties. POLYM. COMPOS., 28:733,738, 2007. © 2007 Society of Plastics Engineers [source] Preparation of oily core polyamide microcapsules via interfacial polycondensation,POLYMER INTERNATIONAL, Issue 4 2003L Soto-Portas Abstract Microcapsules obtained by interfacial polycondensation from an original system based on the polyaddition of specific di- or polyamines and more classical acyl chloride molecules were studied. The originality of the system lies in the fact that the encapsulated agent is the internal phase allowing its incorporation without an organic solvent, which is an advantage from the point of view of environmental protection. Once the optimal parameters of the emulsion were determined, the membrane formation was studied by optimizing the emulsification and reaction times in relation to simultaneous acyl chloride hydrolysis. The microcapsules were obtained by interfacial polycondensation between an excess of amine functions (diamine and diethylenetriamine) and acyl chloride (sebacoyl chloride and 1,3,5-benzene tricarbonyl trichloride) from an oil-in-water emulsion in the presence of 88% hydrolyzed poly(vinyl alcohol) as a surfactant. Various formulations in terms of COCl concentration, crosslinking agent concentration, excess of amine functions, emulsification and reaction times were prepared. The hydrolysis of acyl halide functions is the main parameter which influences the growth of the membrane. The increase in acyl chloride function concentration allows compensation for that lost by hydrolysis, and increases the encapsulation yield to about 90%. The degree of crosslinking of the membrane was controlled in order to minimize the subsequent release of oil by the addition of trifunctional monomers. An optimal formulation was developed offering high encapsulation yield and optimal elastic behaviour. Almost spherical capsules, with a membrane thickness of approximately 500,nm, relatively smooth internal walls and crumpled external walls, were observed by scanning electron microscopy. © 2003 Society of Chemical Industry [source] Structure of Cyclic Aryl Thioester Dimer Based on o -Phthaloyl Dichloride and Bis(4-mercaptophenyl) SulfideCHINESE JOURNAL OF CHEMISTRY, Issue 4 2003Guo Qing-Zhong Abstract A cyclic aryl thioester dimer was prepared by the reaction of o -phthaloyl dichloride and bis(4-mercaptophenyl) sulfide in good yield under pseudo-high dilution conditions via interfacial polycondensation. The structure of the cyclic dimer was confirmed by a combination of MALDI-TOF-MS, FITR, gel permeation chromatography and NMR analyses. The X-ray diffraction study of the single crystal of cyclic thioester dimer obtained from two solutions reveals no severe internal strain on the cyclic structure. [source] Syntheses of cyclic polycarbonates by the direct phosgenation of bisphenol M,JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2005Hans R. Kricheldorf Abstract Bisphenol M was subjected to interfacial polycondensations in an NaOH/CH2Cl2 system with triethylamine as a catalyst. Regardless of the catalyst concentration, similar molecular weights were obtained, and matrix-assisted laser desorption/ionization time-of-flight mass spectra exclusively displayed mass peaks of cycles (detectable up to 15,000 Da). With triethyl benzyl ammonium chloride as a catalyst, linear chains became the main products, but the contents of the cycles and the molecular weights strongly increased with higher catalyst/bisphenol ratios. When the pseudo-high-dilution method was applied, both diphosgene and triphosgene yielded cyclic polycarbonates of low or moderate molecular weights. Size exclusion chromatography measurements, evaluated with the triple-detection method, yielded bimodal mass distribution curves with polydispersities of 5,12. Furthermore, a Mark,Houwink equation was elaborated, and it indicated that the hydrodynamic volume of poly(bisphenol M carbonate) was quite similar to that of poly(bisphenol A carbonate)s with similar concentrations of cyclic species. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1248,1254, 2005 [source] | |||||||||||||