Search

Poly(alkylenetetrasulfide) [poly(R-S4-R)] polymers with R = Me, Et, or Bu are prepared from alkylene dichloride and sodium tetrasulfide by an interfacial polycondensation technique using two quarte...

A three-phase junction formed between a solid electrode placed between solutions of the organic phase and the aqueous phase is employed for localized and electrochemically assisted nylon-6,6 deposition. The fluorine-doped tin oxide (FTO) conductive support (serving as the working electrode) is immersed into the cell filled with the aqueous solution of 1,6- hexanediamine (1,6-DAH) and the organic solution of adipoyl chloride (AC) dissolved in 1,2-dichloroethane. The interfacial polycondensation reaction between these two reagents occurs spontaneously at the liquid–liquid interface at elevated pH and is inhibited when diamine is fully protonated. With this in mind, we have designed a system where the pH close to the three-phase junction was increased using electrochemical water reduction triggering very localized polyamide deposition.

The interfacial polymerization of nylon-6,6 is studied at the polarized liquid–liquid interface. The optimal conditions (concentration of reagents in a biphasic system, pH of the water phase, voltammetric cycling) are used to modify the interface, supported by a microcapillary, giving a platform with molecular sieving properties.

A series of new polyarylates bearing cardo xanthene groups were synthesized by phase-transfer-catalyzed interfacial polycondensation of 9,9-bis[4-(4-chloroformylphenoxy)phenyl]xanthene with various bisphenols containing the isopropylidene, hexafluoroisopropylidene, 1-phenylethylidene, diphenylmethane, cyclohexane, and xanthene structures. High-molecular-weight polyarylates with number-average molecular weight and polydispersity index in the range of 30,100–35,300 and 1.82–2.17, respectively, exhibited high glass transition temperatures ranged from 226°C to 261°C, and their 10% weight loss temperatures were in the range of 421–452°C with char yields above 45% at 700°C in nitrogen. All the polyarylates were amorphous and readily soluble in organic solvents such as dichloromethane, chloroform, tetrahydrofuran, meta-cresol, pyridine, N,N-dimethylformamide, N,N-dimethylacetamide, and 1-methyl-2-pyrrolidinone at room temperature and could be cast into tough, transparent, and flexible films with tensile strengths of 85.6–108.3 MPa, elongations at break of 2–3%, and tensile moduli of 7–9 GPa.

The structure and function of the thin polymeric functional layer in reverse osmosis membranes depend on the kinetics of the interfacial polycondensation (IP) reaction by which the film is formed. It has been a challenge to achieve a quantitative understanding of these kinetics because of the high velocity of the reactions and the complex geometry of the support membrane in which the reaction takes place. In this work, we describe a novel and convenient technique for studying such kinetics, and demonstrate the method on the IP reaction between meta-phenylene diamine and trimesoyl chloride. The method involves studying the reaction in a simple geometry of a drop-continuous phase interface in an emulsion, under such conditions that all transport resistances are eliminated. The reaction course is followed through an on-line pH measurement using a fast probe. Interfacial areas available for reaction are measured by an encapsulation technique, under the conditions of reaction. The methods developed have been used to study the kinetics of the m-PDA-TMC reaction as a function of m-PDA concentration and surfactant (tween-85) concentration, and a surface-area based rate function has been shown to fit the data adequately. (C) 2017 Elsevier Ltd. All rights reserved.

We report here an approach to encapsulate N, N-diethyl-3-methylbenzamide (DEET), an insect repellent, through interfacial polycondensation using modified cellulose nanofiber (CNF) as pickering emulsifier. We found that stearic acid functionalized CNF (mCNF) can be used to form stable pickering emulsions (oil-in-oil and water-in-oil), and further encapsulate DEET using interfacial polycondensation with very high encapsulation efficiency of about 98%. Another major advantage of this approach is that mCNF can act both as pickering emulsifier and also strengthen the barrier properties of microcapsules resulting in significant reduction in release rate of DEET. Interpretation of the release profiles using standard mathematical models proposed by Ritger-Peppas show a factor of three reduction in release rate constant for the microcapsules reinforced with mCNF.

Water-soluble metallocene and organotin-containing polyethers were synthesized employing interfacial polycondensation. The reaction involved various chain lengths of poly(ethylene glycol), and produced water-soluble polymers in decent yield. Commercially available reactants were used to allow for easy scale up. The polymers exhibited a decent ability to inhibit a range of cancer cell lines, including two pancreatic cancer cell lines. This approach should allow the synthesis of a wide variety of other water-soluble polymers.

The current efforts described in this paper are aimed at developing compounds that inhibit the growth of prostate cancer and to identify structure/property relationships that will further assist us towards this goal. The growth of prostate cancer is affected employing a wide range of organotin condensation polymers. The EC50 values are primarily dependant on the nature of the Lewis base but the CI50 is dependent on both the nature of the Lewis base and Lewis acid. EC50 values down to the picogram/mL range are found. A number of products exhibit CI50 values greater than two. For polymers derived from hydroquinone and hydroquinone derivatives ability to inhibit cancer cell growth decreases as the bulk of substituents increases.

In the procedures of designing polystyrene-polyvinyl alcohol-CH (carbon and hydrogen elements) (PS-PVA-CH) triple-layer microspheres, there are many methods such as drop-tower technique, emulsion micro-encapsulation, dip (spin) coating, interfacial polycondensation, and spraying technique to prepare the PVA coating. Drop-tower technique, emulsion micro-encapsulation and dip (spin) coating are most-commonly used. The advantages, disadvantages and the research progress of the three methods are summarized in this paper. Emulsion micro-encapsulation is suitable for preparing double-layer microspheres of sizes smaller then 500 m, with high survival ratio and good quality. However,the preparation process is easily influenced by artificial factors. Small-sized double-layer microspheres can also be prepared by the drop-tower technique, and the preparation period is short. But there are still some problems such as the difficulty in designing thedroplet generator, uneven PVA coating and the difficulty in preparing large-sized microspheres. Dip (spin) coating technique can be used to prepare PS-PVA microspheres with sizes larger than 1000 m, but the spread of PVA coating is affected by many factors in this method, and the prepared PVA coating is too thin and not uniform.

Eight homopolycyanurates have been synthesized by interfacial polycondensation of 2-carbazol-4,6-dichloro-s-triazine with 1,7-dihydroxynaphthalene, 1,4-dihydroxyanthraquinone, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,4-butanediol and 1,8-dihydroxyanthraquinone. All the homopolycyanurates synthesized were characterized for their solubility, density, viscosity, IR, NMR spectral and thermogravimetric parameters.

Aromatic polyesters bearing pendent carboxyl functionalities were prepared by interfacial polycondensation of diphenolic acid, bisphenol A and isophthaloyl chloride with tetrabutylammonium chloride as phase transfer catalyst. The copolyester composition was confirmed with HPLC analysis. The polymerization process and composition of the copolyesters were examined by considering influences of reaction temperatures, time, ratio of feeds, agitation speeds.

Interfacial polycondensation, with its multiphase character and the involvement of several rate and equilibrium processes, presents unique challenges to our ability to understand and design processes for achieving desired properties. In a recent study [1] , we have presented a detailed model for the process and shown that it explains the salient features as reported in the literature for several interfacial systems. In the present paper, we report extensive experimental studies on the polyurea system and their comparison with the model. Two geometries – the spherical geometry of the microcapsule and the flat-film geometry – have been used to study qualitative and quantitative features of the polycondensation and the nature of the film that forms. While some aspects, such as the manner in which the solvent influences the kinetics, confirm earlier findings, inadequacies have been identified in the sample preparation protocols followed in earlier work, because of which property estimations may carry a large error. Improved protocols have accordingly been developed and used to study the development of film properties in time and as a function of the important preparation variables. Detailed molecular weight distributions have been determined using a GPC technique and used to derive important properties of the polyurea (such as Mark–Houwink parameters) as well as to gain insights into mechanisms. The data have been used to determine the rate parameters in the Dhumal and Suresh [1] model. The predictions of the model, as far as trends are concerned, are shown to be satisfactory given the level of uncertainty about parameter values and the complexity of the system being studied. Where discrepancies exist, the reasons have been established and the areas for improvement of the model identified. The findings reported are of interest to applications such as controlled release and membrane separations, in which permeation rate through the membrane is of importance and depends upon various membrane properties like crystallinity, morphology, etc.

Poly(urea-urethane) and polyurea microcapsules were prepared by an interfacial polymerisation using orange oil as a core material and a mixture of polymeric 4,4-methylenediphenyldiisocyanate and toluene diisocyanate in a molar ratio of 1:0.2 as oil-soluble monomers. The membrane composition, its thickness and other properties were varied by changing the type and amount of oil-soluble monomers and water-soluble chain extenders, such as ethylenediamine and diethylenetriamine based on amine groups and 1,4-butanediol and polyethylene glycol 400 based on hydroxyl groups. Studies of the morphology and release behaviour of microcapsules show high dependency on the reaction conditions and reactants’ properties. The release rate of the orange oil from microcapsules is highest when using a polymeric linear chain extender, polyethylene glycol with a molecular mass of 400. Improved mechanical stability and a slower release rate of microcapsules were achieved by a thicker membrane and by using the branched multi-functional chain extender diethylenetriamine.

Several polyarylates were synthesized from the interfacial or high-temperature solution polycondensation reactions of four bisphenols including 2,2-bis(4-hydroxyphenyl)propane (BPA), 2,2-bis(4-hydroxyphenyl)hexafluoropropane (BPAF), 1,1-bis(4-hydroxyphenyl)-1-phenylethane (BPAP), and 1,1-bis(4-hydroxyphenyl)-1-phenyl-2,2,2-trifluoroethane (BPAPF) with various aromatic diacyl chlorides. The basic properties such as inherent viscosity, film-forming capability, crystallinity, and mechanical and thermal properties and the “structure-property” relationships of these polyarylates were investigated. The polyarylates derived from asymmetric BPAP and BPAPF had lower crystallinity and higher solubility and glass-transition temperature (Tg) than the corresponding counterparts based on symmetric BPA and BPAPF. The fluorinated polyarylates revealed higher Tg values and decomposition temperatures than the corresponding nonfluorinated polyarylates.

Linear [m,n]-type polyurethanes (PUs) fully based on renewable materials are synthesized by interfacial polycondensation reaction of diamines derived from the amino-acid cystine with (bis)chloroformates derived from alditols having L-arabino or xylo configuration. The degradability of the new PUs has been enhanced by the introduction of disulfide linkages into the polymer backbone leading to a new group of stimulus-responsive sugar-based polyurethanes able to be degraded by glutathione under physiological conditions. All these polyurethanes are stable up to around 245°C, decomposing at higher temperatures through a one-stage mechanism. The new materials display high chemical homogeneity and degradability in both hydrolytic and reductive environments, with reductions of above 90% in Mw. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41304.

A new method for studying the effect of pH on the polysiloxane network formation using electric fields is presented. The kinetic data obtained using these experiments indicates that the two-step interfacial polycondensation of silanes is strongly dependent on the pH, and the mechanism is essentially different at low and neutral to high values of pH. Very rapid hydrolysis followed by moderate rates of condensation are observed at neutral and high pH. The rate of hydrolysis is drastically reduced, while that of condensation is slightly lowered at low pH as compared to that at high values of pH. The slow hydrolysis reaction at low pH is then exploited to synthesize nonspherical microcapsules. Nonspherical polysiloxane microcapsules with varying aspect ratios from 1.05to 1.97 are synthesized by controlling the applied electric field.

High flux thin-film composite reverse osmosis membranes for brackish water desalination have been fabricated by interfacial polymerization based on aromatic polyamide chemistry. A response surface methodology was used to optimize the concentrations of the monomers, 1,3-Diaminobenzene (MPDA) and 1,3,5-Benzenetricarbonyl trichloride (TMC), and a flux-enhancing additive, Dimethyl sulfoxide (DMSO). The membranes prepared showed a salt rejection of more than 95%. The membranes produced with DMSO additive exhibited a four-to five-fold higher flux rate as compared to the membranes without additive. Quadratic mathematical models have been proposed and verified using diagnostic plots, which adequately describe the flux rate and rejection ability within the limits of the factors investigated. The membrane rejection ability was contributed by a first-order effect of the membrane preparation parameters MPDA, TMC, and DMSO concentration, a quadratic effect of TMC and DMSO concentration, and an interaction effect between TMC and DMSO concentrations. For flux rate, first-order effect of TMC, MPDA, and DMSO concentration, and quadratic effect of MPDA concentration were significant model terms.

Based on the definition of conversion given in Eq. (8.1), (or Eq. 4.1), and according to the correlation between DPn and conversion p (Eq. 8.2), a polycondensation should yield the highest molar mass, when

Polyesters based on a difuranic diacid chloride and various aliphatic diols or bisphenols were prepared by solution and interfacial polycondensation. The latter procedure gave, after optimization, materials with much higher molecular weights. These polymers were characterized in terms of both structure and thermal properties.

Nanocapsules with triethylene glycol dimethacrylate (TEGDMA) as core material and polyurethane as wall material used for self-healing bonding resin were prepared by interfacial polycondensation in miniemulsion. The influence of surfactant and costabilizer concentration on nanocapsules size and stability of nanocapsules was investigated. The size and its polydispersity of the nanocapsules were measured by light-scattering particle size analyzer. When the concentration of SDS were increased from 2.5wt% to 10wt%, the size decreases from 340.5 nm to 258.3 nm, PDI decreased from 0.210 to 0.111. As the concentration of HD increased, the size and PDI were both decreased, When reaching 10wt%, the size was 258.0 nm, PDI was 0.130. SDS and HD play important effect in synthesis of Nanocapsules containing TEGDMA. By changing the surfactant and costabilizer concentration it was possible to synthesize a wide variety of nanocapsules sizes. The performance and technical parameters of nanocapsules had been researched preliminarily, which built the solid foundation for the application to the self-repairing bonding resin.

Pseudopolyrotaxanes and polyrotaxanes of polyamide and the macrocycle cucurbituril are synthesized easily by interfacial polycondensation. With different diammonium ions and diacid chlorides a great variety of poly(amide rotaxane)s is obtained. The structure of the diacid chloride influences the possible motion of cucurbituril on the polymer chain. First attempts to characterize these polyrotaxanes using IR, DTA, 1 H-NMR and elemental analyses are reported.

Several polyarylates based on UV sensitive bisbenzylidenoketones for use as potential second-order nonlinear optical (NLO) materials have been obtained by interfacial polycondensation. The polymers investigated can be divided into two groups: guest-host systems and polyarylates with NLO side-chains. The electro-optic (EO) coefficient, r 33 , was measured in the Pockels experiment. UV crosslinking was applied to increase NLO stability of the investigated materials. Loss and time relaxation of EO coefficient for crosslinked and noncrosslinked polyarylates were also measured.

The glycolysis of poly (ethylene-terephthalate) with bisphenol-A at certain ratios of PET/BPA was carried out in an autoclave reactor at different temperatures for varying periods of time. Then the glycolyzed products were utilized together with bisphenol-A for the synthesis of polyarylates through interfacial polycondensation. The polyarylates obtained (referred to as b/g-polyarylates in this article) possess good thermal characteristics but have lower mechanical strength than typical polyarylate synthesized from pure bisphenol-A by use of the same method. Blending the b/g-polyarylate with polycarbonate improved the impact strength significantly. As a whole, glycolysis with bisphenol-A followed by synthesis of polyarylate through interfacial polycondensation provided a feasible route for the reuse of poly(ethylene terephthalate).

Novel biodegradable and low cytotoxic poly(ester amide)s (PEAs) based on α-amino acids and (L)-lactic acid (L-LA) oligomers were successfully synthesized by interfacial polymerization. The chemical structure of the new polymers was confirmed by spectroscopic analyses. Further characterization suggests that the α-amino acid plays a critical role on the final properties of the PEA. L-phenylalanine provides PEAs with higher glass transition temperature, whereas glycine enhances the crystallinity. The hydrolytic degradation in PBS (pH = 7.4) at 37 °C also depends on the α-amino acid, being faster for glycine-based PEAs. The cytotoxic profiles using fibroblast human cells indicate that the PEAs did not elicit an acute cytotoxic effect. The strategy presented in this work opens the possibility of synthesizing biodegradable PEAs with low citotoxicity by an easy and fast method. It is worth to mention also that the properties of these materials can be fine-tuned only by changing the α-amino acid., A.C. Fonseca acknowledges “Fundação para a Ciência e Tecnologia”, Grant: SFRH/BD/41305/2007. The 1 H NMR data were obtained from Rede Nacional de RMN in the University of Coimbra, Portugal. The Varian VNMRS 600 MHz spectrometer is part of the National NMR Network and was purchased in the framework of the National Program for Scientific Re-equipment (contract REDE/1517/RMN/2005, with funds from POCI 2010 (FEDER) and Fundação para a Ciência e Tecnologia (FCT)). I.J. Correia acknowledges the project PTDC/EME-TME/103375/2008 for financial support.

The toughness of polyarylates was improved by incorporation of 4,4′-thiodiphenol and bisphenol A, being introduced in the aqueous phase of an interfacial polycondensation reaction. The modified polyarylates possessed slightly lower tensile strength and modulus but much higher Izod impact strength due to the flexibility of the incorporated segments. In addition, the superb thermal properties typical for polyarylates were reserved in the modified polyarylate, thus assuring its broad applicability for those applications where extremely stringent criteria of thermal characteristics are required. Die Zahigkeit von Polyarylaten wurde durch den Einbau von 4,4′-Thiodiphenol und Bisphenol A, die in der wasrigen Phase einer Grenzflachenpolykondensation vorgelegt wurden, erhoht. Die modifizierten Polyarylate besitzen leicht erniedrigte Zugfestigkeiten und Zugmoduli, aber aufgrund der Flexibilitat der eingebauten Segmente stark erhohte Izod-Schlagzahigkeiten. Daruber hinaus bleiben die guten thermischen Eigenschaften der Polyarylate nach der Modifizierung erhalten, so das die hergestellten Materialien auch fur Anwendungen mit sehr hohen Anforderungen an die thermische Belastbarkeit geeignet sind.

Oil-containing microcapsules were prepared by using tolylene 2,4-diisocyanate (TDI) as an oil-soluble monomer and diethylere triamine (DETA) or lysine (LYS) as a water-soluble monomer. The diameter of the microcapsules decreased as the emulsifying time was increased within the initial period of three minutes, beyond which no appreciable changes in the diameter were observed. Once DETA was introduced into the aqueous solution to initiate the interfacial polycondensation reaction, reducing the stirring speed could diminish the formation of the membrane fragments, whereas the microcapsule diameter remained unchanged. When lysine was used as a water soluble monomer, the zeta-potential of the TDI-LYS microcapsules was much higher than that of the TDI-DETA microcapsules. The mean diameter of the TDI-LYS microcapsules was smaller than that of the TDI-DETA microcapsules.

International audience; A novel continuous process is proposed and investigated to produce microcapsules by interfacial polycondensation. Polymeric microcapsules are obtained via a two-step process including an initial emulsification of two immiscible fluids in static mixers and a subsequent interfacial polycondensation reaction performed in two different continuous reactors, the Deanhex heat exchanger/reactor or a classical coiledtube. This study is carried out through a step by step approach. A model system involving polyurea as the polymeric membrane and cyclohexane as the encapsulated species is chosen. A semi-batch reaction kinetic study is first performed in order to obtain kinetics data of the polycondensation reaction and to highlight hydrodynamic issues that can happen when running the encapsulation reaction in classical stirred tank. Parameters influencing droplets size obtained when carrying out emulsification in static mixers are then investigated. The hydrodynamic of the Deanhex reactor used is also characterized in terms of mixing time and residence time distribution. To validate the innovative continuous process, the emulsion droplets obtained at the static mixer outlet are encapsulated firstly in the Deanhex reactor and secondly in the coiled-tube. The apparent reaction kinetics and microcapsules characteristics corresponding to different operating conditions are discussed.

Products with hydroxyl ends were synthesized from the esterification of bisphenol-A, terephthalic acid and ethylene glycol. These ester products were then used for synthesis of polyarylate by interfacial polycondensation. Not only the relative concentrations of reactants for esterification but also the conditions for interfacial polycondensation, such as the monomer ratio between two phases and the reaction time, play significant roles in affecting the properties of final products. Under proper synthesis conditions, the polyarylate formed could possess equivalent thermal characteristics and much higher impact strength in comparison with unmodified polyarylate due to the incorporation of flexible aliphatic segments from ethylene glycol. X-ray diffraction showed the existence of aliphatic segments would induce small degree of orderly alignment locally in structure.

Photosensitive microcapsules, which are thermally quite stable, are formed via interfacial polycondensation in which one of the shell-forming reactants contains an azo function. An azo monomer, containing α,ω-carboxylic diacid dichloride was reacted with a trifunctional aliphatic amine on the oil-water interface resulting in a shell-forming crosslinked polyamide. The size of the resulting photosensitive microcapsules was determined. It could be shown that these microcapsules can be opened by means of UV-light. Durch Grenzflachenpolykondensation wurden photosensitive, thermostabile Mikrokapseln hergestellt, wobei eine der Kondensationskomponenten eine Azo-Funktion enthalt. Das Hullwandpolymere der erhaltenen Mikrokapseln wurde durch Reaktion eines die Azogruppe tragenden Dicarbonsaurechlorids mit einem aliphatischen Triamin gebildet. Die Grose der erhaltenen photolabilen Mikrokapseln wurde bestimmt sowie ihre photolytische Offnung durch Bestrahlung mit UV-Licht nachgewiesen.

The synthesis of of hydrophilic polyamides by polycondensation of 2,3,4,5-tetra-O-acetyl-galactaroyl dichloride with various heterocyclic carbohydrate-derived diamines and hexamethylene diamine. Polyamides with free hydroxy groups were obtained by removal of acetyl groups

3,5-Bis(p-hydroxybenylidene)-isopropylpiperidinone (BHIP) and 3,5-divanillylidene-isopropylpiperidinone (DVIP) were used as new starting materials for preparing new unsaturated polyesters. The polyesters were prepared by reacting BHIP or DVIP with adipoyl, sebacoyl, isophthaloyl or terephthaloyl dichlorides utilizing the interfacial polycondensation technique. In addition, the model compounds were synthesized by reacting BHIP or DVIP with benzoyl chloride. The model compounds were characterized by 'H-NMR, IR, and elemental analyses. The polyester samples have been characterized by elemental and spectral analyses. All the synthesized polymers readily dissolved at room temperature in dimethylsulphoxide or concentrated sulphuric acid. The thermal properties of the polymers were evaluated and correlated to their structural units by TGA measurements. X-ray analysis of the polymers showed that all the polyesters are amorphous.

A model and a simple measurement technique for time of encapsulation have been developed to study the microencapsulation of butachlor in polyurea shell by means of interfacial polymerization. The model is based on diffusion of the hydrophilic monomer through the polymeric shell with an interfacial reaction at the inner surface while the rneasurement technique is based on the indirect determination of the concentration of the hydrophilic monomer in the continuous phase by monitoring the pH. Measurements show that capsule sizes ranging from 1 to 20 prn can be produced, and the surface to volume mean size varies only from 2 to 6 pm for a large variation in rpm of the agitator. Time of encapsulation is found to be approximately proportional to the microcapsule size, and it varies from 150 to 300 s. Both the data and the model were used to discern that the process is kinetically-controlled by and large. It is also shown that time of encapsulation varies with the square of the capsule size in a diffusion-controlled regime.

The surface activity of aqueous solutions of melamine formaldehyde resins was investigated at different stages of the resin synthesis. Partially methanol etherigied melamine formaldehyde resins, which are able to form microcapsules, are reactive surface active compounds. The formation of capsuole walls with these resins proved to be a one-component interfacial polycondensation reaction. Die grenzflachenaktivita wasriger Losungen von Melamin-Formaldehyd-Harzen wurde in verschiedenen Stufen der Harzynthese untersucht. Zur Bildung von Mikrokapseln geeignete, partiell methanolveretherte Melamin-Form-aldehyd-Harze sind reaktionsfahige grenzflachenaktive Verbindungen. Die Bildung der Kapselwande aus diesen Verbindungen ist eine Einkomponenten-Grenzflachenpolykondensation.

Etude de la cinetique en variant le rapport molaire bisphenol A/chlorure d'isophtaloyle. Deduction de la forme integree de l'equation de vitesse pour des reactions non stœchiometriques a partir de l'equation R=d[B]/dt=K[B][I]. Bon accord entre les donnees de l'equation

Preparation du polycarbonate du bisphenol A ayant une viscosite intrinseque de 1,1 dl/g par polycondensation interfaciale catalysee par la 4-dimethylaminopyridine

Interfacial polycondensation is an important polymerization technique that encapsulates a variety of active principles. Mechanisms governing the reaction and interplay of physical and chemical rate processes need to be understood for both rational design of reaction equipment and the process control to produce capsules with desired characteristics. A theoretical and experimental study of the process is reported here. Kinetic data were obtained over a range of concentrations, monomer mole ratios and polymer film thicknesses, using a technique that relies on the on-line measurement of pH as a function of time. To understand the mechanisms the reaction was slowed down by reducing the interfacial area. A minimum thickness of the polymer was observed to be necessary so that capsules preserve their integrity and do not break up. The theoretical model developed considers ionic equilibria in the aqueous phase and the resistances due to external mass transfer, diffusion through the polymer, and interfacial reaction. Under the conditions chosen, the resistance due to the chemical reaction is generally more dominant. Values of rate parameters were determined by fitting the model to the experimental data. Observed variations in the diffusivity between different experiments were rationalized through a study of the crystalline structure of polymers.

Synthesis of Aromatic Polyesters by Interfacial Polycondensation Using Immiscible Binary Solvents

Poly(biscarbamoyl disulfides) have been synthesized by the interfacial polycondensation of dithiobis(carbonyl chloride) with secondary diamines. The polymers obtained in good yields were of sufficiently high molecular weight to form films. The polymer films decomposed by UV irradiation with liberation of carbonyl sulfide.

The effect of organic phase and stirring speed on the preparation of nylon microcapsules using 1,6-hexamethylene diamine and sebacyl chloride in the interfacial polycondensation reaction has been investigated. Carbon tetrachloride alone and the traditional 20% chloroform in cyclohexane were found to be poor solvents producing non-separable clumps of microcapsules. Mineral oil, singly, and in combination with varying amounts of carbon tetrachloride, cyclohexane, or chloroform yielded discrete free-flowing microcapsules.In general, lower speeds of stirring produced products which were more discrete and free flowing than those prepared at higher stirring rates.

Reaction rates of interfacial polycondensation of bisphenol A and chlorobisphenol II with isophthaloyl chloride were investigated. Rate constants and activation energies were determined The reaction rate was found to depend on stirring speed, catalyst, type of bisphenol, and temperature.

It has been established that of the known N′,N″-dimethyldi-imides of N″′,N″′′-hexamethylene-bis-aspartic acid the stereoisomer with m.p. 114–115° is a racemic mixture, and the isomer with m.p. 74·5–75° is a mesoform. For interfacial polycondensation of the stereoisomeric diaminodi-imides with terephthalic acid chloride the optimum systems are chloroform-water and benzene-water, with initial di-imide concentrations of 0·30 to 0·35 mole/l. (CHCl3 : H2O) and 0·15 mole/l. (C6H6 : H2O). The best acceptors are Na2CO3 and NaHCO3. An optically active poly(amido)imide with [M]D = 95·4° has been synthesized on the basis of the optically active diaminodi-imide.

Interfacial polycondensation in aqueous and non-aqueous systems has been investigated in order to synthesize various polyamides having functional groups. Rigid aromatic polyamides having pyridine moieties (PPy) were synthesized by interfacial polycondensation using an aqueous system and the solution properties of PPy in concentrated sulfuric acid were investigated in terms of solution viscosity and lyotropic behavior. Interfacial polycondensation in a non-aqueous system using two immiscible solvents was found to be useful for the synthesis of aromatic polyesters and copolyesters.

A quasi-steady state model, based on two parallel modes of diffusion and a polycondensation reaction at the inside surface of a microcapsule, is formulated to compute the time of this microencapsulation process. The predicted times of encapsulation are in agreement with observed values reported in patents. It is also shown that, for small shell thickness, the process is reaction-controlled. Un modale en ragime quasi stationnaire basa sur deux modes de diffusion parallales et une raaction de polycondensation a la surface interne d'une microcapsule, a ata mis au point pour calculer par ordinateur le temps nacessaire au procada de microencapsulation. Les temps d'encapsulation pradits concordent avec les valeurs expakimentdes donnaes dans les descriptions de brevets. On montre agalement que le procada est contrǒla par la raaction pour des petites apaisseurs d'enveloppe.

Results for pilot plant scale experiments on the preparation of polycarbonates are presented. The effect of end-groups content of the oligomer on the efficiency of polycondensation was quantitatively studied and procedures of molecular weight control with different chain stoppers have been investigated. It was found that for an efficient polycondensation of oligomer the contents of the reactive groups have to be as follows: minimum 30 mole-% of OCOCl, and relation OCOCl:OH=0.5. The same applies for an effective and reproducible molecular weight control. The best effect of chain stopping is observed when a molecular weight regulator is added both in phosgenation and polycondensation stages. Es wird uber die Ergebnisse von Experimenten mit einer Versuchsanlage zur Herstellung von Polykarbonaten berichtet. Dabei wurde der Einflus des Endgruppengehaltes der Oligomeren auf die Polykondensation quantitativ verfolgt und die Methoden der Molekulargewichtsregelung mit verschiedenen Kettenabbrechern untersucht. Es ergab sich, das fur eine effektive Polykondensation der Oligomeren der Gehalt an reaktiven Gruppen mindestens etwa 30 Mol-% an OCOCl und das Verhaltnis von OCOCl zu OH mindestens 0,5 betragen soll. Dasselbe betrifft eine effektive und reproduzierbare Molekulargewichtsregelung. Der Effekt des Kettenabbruchs ist am besten, wenn der Kettenabbrecher sowohl im Phosgenierungs-als auch im Polykondensationsstadium zugegeben wird.

The possibility of an inter facial polycondensation of 1,3-bis(hydroxymethyl)-1,3-bis(γ-hydroxypropyl)- and 1,3-bis(γ-o-hydroxyphenylpropyl)-1,1,3,3-tetramethyl-disiloxanes with COCl2 is reported here for the first time, and some of the process mechanisms have been investigated. The produced polysiloxane carbonates have been found to have Mn values between 1000 and 500, to be heat resistant in air up to 250–300°C.

New polythioesters have been obtained in the interfacial polycondensation of 4,4′-di(mercaptomethyl)benzophenone with terephthaloyl, isophthaloyl and phthaloyl chlorides. The reactions were carried out at room temperature with the use of 10% excess of acid chloride per mole of mercaptan with vigorous stirring (2000 rpm). The organic phase was composed of benzene and hexane in equal volumes and the ratio of this mixture to water also was 1:1. The structure of the polythioesters was determined from elementary analysis and the infrared spectra. The molecular weight was not determined because of the very low solubility of polythioesters. Some thermal, mechanical, and electrical properties of the products have been determined. Products of dimercaptan with the terephthaloyl and isophthaloyl chlorides show the best properties.