Solubility Of Oligomers Research Articles

Flexibility On-Demand: Multivariate 3D Covalent Organic Frameworks.

Dynamic 3D covalent organic frameworks (dynaCOFs) have shown concerted structural transformation and responses upon adaptive guest adsorption. The multivariate (MTV) strategy incorporating multiple functionalities within a backbone is attractive for tuning the framework flexibility and dynamic responses. However, a major synthetic challenge arises from the different chemical reactivities of linkers usually resulting in phase separation. Here, we report a general synthetic protocol for making 3D MTV-COFs by balancing the linker reactivity and solvent polarity. Specifically, 15 crystalline and phase pure MTV-COF-300 isostructures are constructed by linking a tetrahedral unit with eight ditopic struts carrying various functional groups. We find that the electron-donating groups make the linker reactivity too low to allow the reaction to proceed fully, while the electron-withdrawing groups afford increased reactivity and hardly yield crystalline materials. To overcome the crystallization dilemma, the combination of polar aprotic with nonpolar solvents was used to improve the solubility of oligomers and slow the reaction kinetics in MTV-COF synthesis. We demonstrate the abilities of these MTV-COFs to tune gas dynamic behaviors and the separation of benzene and cyclohexane. These findings reveal the integration of multivariate functionalities into dynaCOFs with on-demand flexibility to achieve dynamic synergism in particular applications, outperforming their pure, monofunctional counterparts.

Helical Structures of Nylon-Like Oligomers Consisting of 1,2-Diamine and 1,2-Dicarboxylic Acid Building Blocks Containing a Five-Membered Ring Constraint.

A series of nylon-like oligomers was synthesized, which consisted of alternating cyclic 1,2-diamine and 1,2-dicarboxylic acid building blocks with a five-membered ring constraint. The nylon 2 4 oligomers are symmetric and display helical structures similar to the β-peptide 12-helix with intramolecular 12-membered ring hydrogen bonds. The cyclopentane moiety allows each building block to promote 12-helical folding. In addition, a tartaric acid derivative with the acetonide moiety increases the solubility of oligomers in common organic solvents and promotes helical folding.

Synthesis, optical, electrochemical, and magnetic properties of new ferrocenyl chalcone semiconductors for optoelectronic applications

A ferrocenyl chalcone (OFcPV) with attractive optical and magnetic properties for its potential application in optoelectronic devices, excellent processability in solution, and thermal stability is reported. It was derived from the synthesis of ferrocenyl chalcone with different degrees of conjugation and the preliminary selection of the most attractive molecule based on its linear optical and electrochemical properties, and processability. Three ferrocene-derived compounds: a low-molecular weight molecule (3FcPV), an oligomer (OFcPV), and a polymer (PFcPV) were synthesized through Friedel–Crafts reactions and aldol condensations. The chemical structure of the compounds has been elucidated by proton nuclear magnetic resonance and Fourier-transform infrared spectroscopies. UV–Vis and fluorescence spectroscopies were used to evaluate the optical properties of these new compounds. The frontier orbitals levels of the materials deposited as films were determined using cyclic voltammetry. The optical bandgaps for 3FcPV, OFcPV, and PFcPV were 2.8, 2.4, and 2.36 eV, respectively. These results place these materials within the organic semiconductors and evidence the influence of the degree of electronic conjugation of the molecule in the reduction of the bandgap. The results showed that the oligomer and the polymer possess similar electronic and optical properties. However, the oligomer solubility improves the processability necessary for the manufacturing photonic devices. OFcPV was characterized by Z-scan technique, and the results indicate that OFcPV is candidate to be used as an optical limiter, fast optical switch, or optical logic gates. Also, OFcPV exhibits quasi-superparamagnetic behavior resulting from the iron disposal in the structure.

Peroxide-initiated graft modification of thermoplastic BioPolyesters: Introduction of long-chain branching

The chemical modification of polylactic acid (PLA) and related polyesters by peroxide-initiated grafting of multifunctional allylic and acrylic monomers is described. Solvent-free, melt-state reactions of PLA and triallyl trimesate (TAM) are shown to be remarkably efficient compared to analogous reactions of polyolefins such as poly(ethylene-co-octene) (EOC), requiring very low reagent loadings to produce a long chain branched (LCB) architecture. A systematic study of potential transesterification chemistry confirms that ionic reactions do not contribute significantly to PLA reactivity under typical grafting conditions. Further explorations of H-atom abstraction and monomer addition yields demonstrate that PLA is relatively unreactive toward the radical reactions that support LCB production. Careful examination of the solubility of coagent intermediates reveal dramatic differences in oligomer solubility between a hydrocarbon system and an ester-based matrix. Whereas TAM conversion in hydrocarbon leads to a precipitation polymerization that removes coagent from solution, reactions conducted in the polyester do not incur losses of oligomeric intermediates, indicating that the ability of PLA to retain multi-functional intermediates is the underlying cause of its remarkable LCB grafting yields.

Size control of aromatic polyamide hollow spheres prepared by reaction-induced phase separation

Size control of the poly (1,4-phenylene-5-hydroxyisophthalamide) hollow spheres was examined by tuning the polymerization condition, focusing on concentration, temperature and solvent. Higher concentration lowered the diameter owing to the higher degree of super-saturation for nucleation. Temperature drop during the polymerization just before the nucleation was so effective to make the diameter smaller. Moreover, the diameter was susceptive to the solubility of oligomers in the solvent, and higher content of liquid paraffin in the aromatic solvent lowered the solubility, resulting in the decrease in the diameter. Based on these results, the combination of the temperature drop and the solvent effect was the most desirable to prepare the smallest hollow spheres, and the diameter of hollow spheres could be controlled from 4.4 to 0.7 μm.

Effect of Acidic and Basic Environment to the Degradation Behavior of PLGA Nanocapsules for Biomedical Application

Poly (D, L lactic-co-glycolic) acid (PLGA) is very famous with its biodegradability property. In the formed of nanocapsules (NPs), it is applied as contrast agent or for drug encapsulation. To pursuit better function of PLGA NPs, a study about degradation behaviour is necessary because it is related to NPs drug release pattern. To conduct this research, PLGA NPs was prepared by emulsification solvent-evaporation method and incubated in phosphate, acetate, and carbonate buffer to observe the effect of different pH into degradation rate of PLGA NPs. The acidic environment tends to have fast destructuration with less lactate monomer produced indicating less breaking of ester bonds. While in the basic condition, the degradation is done slowly with high production of lactate. This phenomena is related to the solubility of oligomers. So, it is clear that different pH affects the degradation mechanism of PLGA NPs and it can be applied to encapsulate drug for gastric or small intestinal cancer which have acidic and basic environment respectively.

Improved chemical resistance of ink‐jet printed micropatterns on glass by using dual‐functional compositions

ABSTRACTUV curable and UV/moisture dual‐functional oligomers were synthesized by grafting trimethoxysilane and methacrylate segments on the polyimide oligomer chains. These oligomers and a dual‐functional monomer were used as ink compositions to enhance the chemical resistance of ink‐jet printed LCD color filter micropatterns, without sacrificing jetting performance. The molecular structure and molecular weight of the oligomers were altered to adjust the solubility of oligomer in monomers, together with jetting trajectory, drop size uniformity, and deposition accuracy of the ink‐jet inks. The chemical resistance, optical property, and mechanical property of the printed patterns depend on the oligomer structure, the arrangement of trimethoxysilane groups, and the molecular chain length. Straight lines and uniform dot arrays with excellent chemical resistance can be achieved. Dot patterns made of polymer‐silica hybrid materials and pigments remain unchanged after being immersed in γ‐butyrolactone for 200 min. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2049–2055, 2013

Enzymatic synthesis of oligoesculin: structure and biological activities characterizations

The oligomerization of esculin, catalyzed by the laccase from Trametes versicolor, was realized in an attempt to improve the properties of this glycosidic coumarin. MALDI-TOF analyses showed a degree of oligomerization up to 9, whereas NMR spectra revealed the formation of C–C and C–O bridges, which involve both the phenolic and the glucosidic part of the coumarin. The solubility of oligomers is 189-fold higher than esculin’s solubility. Moreover, antioxidant properties of oligomers were correlated with their mass; the more the mass, the more the xanthine oxidase inhibitory activity and the radical scavenging activity are important. These experimental results were completed by in silico structural investigations, which suggested the preferential formation of C8–C8 linkages between esculin units during the oligomerization reaction.

Consideration of Solvent Effect on Precipitation Polymerization of Poly(ether-ketone)s via Friedel-Craft Acylation

Precipitation polymerization of diphenyl ether and isophthaloyl chloride catalyzed by AlCl3 via Friedel-Crafts acylation was examined in various solvents to clarify the polymerization behavior. Polymerizations were carried out in three categorized solvents based on the solubility to both catalyst and polymer, which were cyclohexane (CH), 1,2-dichloroethane (DCE) and DCE containing 2 wt% nitrobenzene (2%-NB). In DCE which was widely used, the oligomers were precipitated as a form of the complex with AlCl3 at the early stage of polymerization. The precipitates of the oligomers were swollen by the solvent, in which any short-range regular structure did not exist. The further polymerization proceeded even in the precipitates with eliminating by-produced HCl, and high molecular weight poly(ether-ketone)s (PEK) were finally formed. Nevertheless the reaction in 2%-NB yielded the well-swollen precipitates, the high molecular weight PEK was not synthesized in the precipitates because the reaction was terminated by not only the inefficient elimination of HCl due to the higher solubility of HCl but also the deactivation of catalyst by coordination of NB to AlCl3. Although the precipitation occurred more readily in CH due to the lower solubility of oligomers, the polymer was not synthesized in the precipitates. The resulting precipitates comprised of the dimers were not swollen in this case, and thereby it was very difficult to react between dimers and eliminate HCl from the precipitates. The solvents having high miscibility to catalyst and the polymers, low solubility of HCl gas, and no basicity are necessary for making high molecular weight polymers via the precipitation polymerization.

The Oxidative Polycondensation of Benzylidene-4′-hydroxyanilene using Air O2, NaOCl and H2O2: Synthesis and Characterization

In this work, the oxidative polycondensation reaction conditions of benzylidene-4′-hydroxyanilene (B-4′-HA) were studied using oxidants such as air O2, H2O2 and NaOCl in an aqueous alkaline medium between 40 and 95 ○C. Oligo-benzylidene-4′-hydroxyanilene was characterized by 1H-NMR, FT-IR, UV-Vis, size exclusion chromatography (SEC) and elemental analysis techniques. The solubility of oligomer using organic solvents such as DMF, THF, DMSO, methanol, ethanol, CHCl3, CCl4, toluene, acetonitrile, ethyl acetate was investigated. According to air O2 oxidant (flow rate 8.5 L/h), the conversion of B-4′-HA was 82.0% in optimum conditions such as [B-4′-HA]0=[KOH]0=0.1015 mol/L at 50 ○C for 25 h. According to the SEC analysis, the number-average molecular weight (Mn), weight-average molecular weight (Mw) and polydispersity index (PDI) values of O-B-4′-HA were found to be 1852 g mol−1, 3101 g mol−1 and 1.675; 2123 g mol−1, 4073 g mol−1 and 1.919; 2155 g mol−1, 4164 g mol−1 and 1.932, using air oxygen, NaOCl and H2O2 oxidants, respectively. Also, Thermo gravimetric analysis (TGA) showed oligo-benzylidene-4′-hydroxyanilene to be unstable against thermo-oxidative decomposition. The weight loss of O-B-4′-HA was found to be 95.87% at 1000 ○C.

Electrochemistry of Conductive Polymers : XXIX. Polyfluorene Growth in Dichloromethane and Acetonitrile: A Comparative Study

A comparative study on polyfluorene (PFl) growth has been carried out in dichloromethane and acetonitrile solutions employing cyclic voltammetry, kinetic measurements, electrochemical quartz crystal microbalance (EQCM) and in situ spectroelectrochemical techniques. The results indicate that fluorene is polymerized more effectively in than in and the PFl films prepared in generally have better physicochemical characteristics than those in The polymerization reaction rates fluctuate due to the passivation/depassivation processes taking place in while they decrease steadily with increasing potential cycle number in EQCM studies show that the current efficiencies are about 100% in while they average about 25% in Spectroelectrochemical studies show that monomers are quickly polymerized to make long-chain oligomers in while the chain lengths are generally shorter for polymers prepared in These differences are attributed to the differences in solvent characteristics such as their dielectric constants, leading to a different solubility of oligomers and different ion stabilization. © 2004 The Electrochemical Society. All rights reserved.

Sugar monomer and oligomer solubility: data and predictions for application to biomass hydrolysis.

Oligomer solubility could potentially play an important role in controlling the rates and yields in the thermochemical hydrolysis of hemicellulose as a pretreatment for subsequent enzymatic conversion of cellulose. However, limited data or models are available to describe the aqueous solubility of sugar monomers and oligomers. In this work, we measured the solubilities of sugars common to many biomass feedstocks in the temperature range of 25-30 degrees C. Then we reviewed solubility models for sugars from the open literature. Finally, we applied models to test their ability to describe this and other data reported in the literature. It was found that the solubility of sugar monomers was not well described by the ideal solubility law or other more complex models. However, with an empirical adjustment to the enthalpy of fusion, the ideal solubility law was able to approximately predict the solubility of cello-oligomers. Based on these results, solubilities for low molecular weight xylo-oligomers are predicted to investigate their possible importance in pretreatment and define further experimental measurements needed to improve our understanding of sugar and oligomer solubility.

Electrochemical quartz crystal microbalance studies on the electropolymerization processes of ortho-phenylenediamine in sulfuric acid solutions

The electropolymerization of ortho-phenylenediamine (o-PD) in 0.10 M H2SO4, 0.10 M H2SO4+0.40 M Na2SO4, and 0.50 M H2SO4 solutions was studied using an electrochemical quartz crystal microbalance. The poly-(ortho-phenylenediamine) (PoPD) films were formed during continuous potential cycling between −0.40 V and +0.95 V versus SCE. The decrease in the resonant frequency of the quartz crystals during electropolymerization of phenylenediamine demonstrated that the deposition of the polymer films occurred mainly in the potential range where the monomers were anodically oxidized. Dramatic changes in the resonant frequency and the resonant admittance were observed during the redox processes at potentials below +0.20 V. At least two kinds of deposits could be distinguished in the PoPD films. The surface concentration of the electroactive sites of the polymer prepared in 0.10 M H2SO4 and in 0.10 M H2SO4+0.40 M Na2SO4 solutions were much higher than that prepared in 0.50 M H2SO4. The acidity of the solution rather than the concentration of the anions of the electrolyte was found to have a strong influence on the electropolymerization processes. The results were discussed in the light of the effects of the solubilities of oligomers in solutions during the electropolymerization processes and the changes in the structures of the initially formed polymer films.

Effect of anions on the nucleation and growth mechanism of polyaniline

In this work we show that the nucleation and growth mechanism (NGM) of polyaniline (PANI) films depends on the anions present in the electrolyte, the solubility of oligomers formed before the nucleation process and the stirring conditions. The NGM of PANI in an unstirred solution can be explained by assuming that this process is preceded by the formation of a high density oligomeric layer which is located near the electrode | solution interface. A thick oligomeric layer obtained with a high concentration of monomers or with anions of the type HSO 4 − or SO 4 2−, which form more soluble species with the oligomers. Under these conditions, diffusion-controlled progressive nucleation with three-dimensional growth is found. However, when the monomer concentration is low or ClO 4 − anions are present, the thickness is decreased and the NGM is either instantaneous nucleation with three-dimensional growth or progressive nucleation with two-dimensional growth.

Retention characteristics of high-molecular-weight compounds in capillary supercritical fluid chromatography

The separation of oligomers of two different polymers using capillary supercritical fluid chromatography was studied. Pressure programming was used to achieve optimum separation of the oligomers. From a comparison of the separation of these oligomers with different length columns it was demonstrated that oligomer solubility was primarily controlling the separation. Accordingly, changing the stationary phase, shortening the column or not even using a stationary phase had minimal effect on the separation of the oligomers.

Oxidative doping studies of PPV oligomers

Oligomers of the electroactive polymer poly( p-phenylene vinylene (PPV) were oxidatively doped in dilute CH 2Cl 2 solution with SbCl 5. In the dimer and trimer cases, stable charged species are formed which have characteristics similar to bipolarons formed during the oxidative doping of PPV, with ω o/ Δ splittings deep in the gap very similar to those found in PPV. Similar splittings are found in the tetramer, but the lack of oligomer solubility hindered detailed measurements. The bipolaron-like intermediates formed by chemical oxidation exhibit weak confinement qualitatively similar to the PPV bipolarons formed electrochemically or by photoinduced absorptions.

Influence of the specific interaction of components on the mutual solubility of modified oligomers of isobutylene and epoxide resins

An interference micromethod has been used to study the solubility of the components of epoxydiane resin-isobutylene oligomer systems with different reactive terminal groups. The introduction of fucntional groups with high reactivity yields homogeneous systems even when the nature of the components differs sharply. The possibility of predicting the solubility of oligomers with reactive groups on the basis of Flory's theory of solutions is shown.

Solubility of non‐polar polymers in microemulsions I. Solubility of oligomers

Solubility of non‐polar polymers in microemulsions I. Solubility of oligomers