Different Degree Of Branching Research Articles

Novel highly efficient branched polyfluoro sulfonated polyimide membranes for application in vanadium redox flow battery

Branched polyfluoro sulfonated polyimide (BPFSPI) membranes with different degree of branching and degree of sulfonation are designed and prepared for application in vanadium redox flow battery (VRFB). The optimized BPFSPI-10-50 membrane exhibits a similar proton conductivity (2.94 × 10−2 S cm−1) as that of the commercial Nafion 212 membrane (3.20 × 10−2 S cm−1) and a much higher membrane selectivity (3.16 × 105 S min cm−3) than Nafion 212 membrane (0.42 × 105 S min cm−3). Meanwhile, BPFSPI-10-50 membrane is durable in V(V) + H2SO4 solutions for more than 30 d. Both coulomb efficiency (CE) and energy efficiency (EE) of BPFSPI-10-50 membrane are higher than those of Nafion 212 membrane (CE: 94.2–98.9% vs 73.9–94.9%, EE: 68.0–86.9% vs 67.7–77.9%) in VRFB (40–200 mA cm−2) test. Besides, BPFSPI-10-50 membrane displays slower self-discharge rate and excellent discharge capacity retention compared to Nafion 212 membrane. Furthermore, the VRFB with BPFSPI-10-50 membrane shows very stable CE and EE (>98% and 76%) over 200 charge-discharge cycles. Accordingly, the BPFSPI-10-50 membrane with superior cost-performance ratio has an outstanding prospect for application in VRFB.

Coherent Nonlinear Resonances of Saturated Absorption at Transitions from the Ground <sup>1</sup>S<sub>0</sub> Atomic State in the Spectroscopy of Unidirectional Waves

The shapes of the saturated absorption resonances at transitions from the ground 1S0 atom state in a gas medium in the field of two unidirectional waves are investigated both analytically and numerically. It is shown for the first time that the spectra of nonlinear resonances are formed by processes in the two-and three-level V-schemes resulting from the degeneracy of the upper P transition state, are qualitatively different at the resonant transition and transitions to the more excited atom states. It is established that the physical causes for differences of these spectra are due to the different degree of branching of the radiation from the excited to the ground state (the degree of openness) of transition. The degree of openness of transition determines the amount of contributions of coherent processes to the resonance shapes both in the system of two levels (coherent population beats) and three levels (nonlinear interference effect).

A Novel Group-based Correlation for the Ignition Delay Time of Paraffinic-type Fuels

ABSTRACT A group contribution equation is proposed for the prediction of the cool flame and main auto-ignition delay time for linear and slightly branched paraffinic fuels. The experiments were carried out in a constant volume combustion bomb where pressure and temperature were modified for five linear paraffinic hydrocarbons (n-C10, n-C12, n-C14, n-C16 and n-C18) and three C16 isomers with different degree of branching (2-methylpentadecane; 2,6,10-trimethyltridecane and 2,2,4,4,6,8,8-heptamethylnonane). An Arrhenius-type correlation is proposed, with extended parameters to the number of groups CH3, CH2 and CH and the equivalence ratio. The proposed equation has enough accuracy to estimate the autoignition delay times of paraffinic fuels (from n-dodecane to n-octadecane) for temperature ranging from 535 to 650ºC and pressure from 11 to 21 bar.

Conformation and cooperative order-disorder transition in aqueous solutions of β-1,3-d-glucan with different degree of branching varied by the Smith degradation.

β-1,3-d-glucan with different degrees of branching were obtained by selectively and gradually removing side chains from schizophyllan, a water-soluble triple helical polysaccharide, using the Smith degradation. Size exclusion chromatography combined with a multi-angle light scattering detection was performed in aqueous 0.1 M NaCl. The degree of branching decreased after the Smith degradation, while the molar mass distributions were almost unchanged. The molecular conformation of the Smith-degraded β-1,3-d-glucan was analyzed on the basis of the molar mass dependency of the radius gyration, and found to be comparable to the original triple helix of schizophyllan. Differential scanning calorimetry in deuterium oxide-hexadeuterodimethylsulfoxide mixtures was performed to investigate the effects of the degree of branching on the cooperative order-disorder transition. Removal of side chains affects both the transition temperature and transition enthalpy. The ordered structure is formed by the residual side chains in the triplex unit, so that the linear cooperative system of the triplex is maintained after the Smith degradation.

Martini coarse-grained model for polyethylenimine.

As a polycation with diverse applications in biomedical and environmental engineering, polyethylenimine (PEI) can be synthesized with varying degrees of branching, polymerization, and can exist in different protonation states. There have been some interests in molecular modeling of PEI at all-atom or coarse-grained (CG) levels, but present CG models are limited to linear PEIs. Here we present the methodology to systematically categorize bond lengths, bond angles and dihedral angles, which allows us to model branched PEIs. The CG model was developed under the Martini scheme based on eight ~600 Da PEIs, with four different degree of branching at two different protonation states. Comparison of the CG model with all-atom simulations shows good agreement for both local (distributions for bonded interactions) and global (end-to-end distance, radius of gyration) properties, with and without salt. Compatibility of the PEI model with other CG bio-molecules developed under the Martini scheme will allow for large-scale simulations of many PEI-enabled processes. © 2018 Wiley Periodicals, Inc.

Effect of airflow presence during the manufacturing of biodegradable films from polymers with different structural conformation

Abstract The preparation method to obtain biodegradable films has an important effect on their performance. The drying of film-forming solutions is a very important step usually ignored during the manufacturing of biodegradable films. The objective of this study was to evaluate the effect of the drying process (natural convection or forced convection) on the functional properties of films from polymers with different structure. The film-forming solutions were dried using airflow (forced convection) and no air circulation (natural convection). Films from polyvinyl alcohol (PVOH, with linear structure) and polymers with different degree of branching (potato starch and high amylose corn starch) were evaluated. Films dried in forced convection showed important changes in the water adsorption, mechanical and thermal properties. Drying under forced convection could have promoted the formation of intermolecular bonds during the rearrangement of the polymer chains resulting in films with greater barrier to water vapor and better mechanical performance.

Hyperbranched Glycopolymers of 2-(α-d-Mannopyranose) Ethyl Methacrylate and N,N'-Methylenebisacrylamide: Synthesis, Characterization and Multivalent Recognitions with Concanavalin A.

A series of novel hyperbranched poly[2-(α-d-mannopyranosyloxy) ethyl methacrylate-co-N,N’-methylenebisacrylamide] (HPManEMA-co-MBA) are synthesized via a reversible addition fragmentation polymerization (RAFT). The dosage ratios of linear and branch units are tuned to obtain different degree of branching (DB) in hyperbranched glycopolymers. The DB values are calculated according to the content of nitrogen, which are facilely determined by elemental analysis. The lectin-binding properties of HPManEMA-co-MBA to concanavalin A (ConA) are examined using a turbidimetric assay. The influence of defined DB value and molecular weight of HPManEMA-co-MBA on the clustering rate is studied. Notably, HPManEMA-co-MBAs display a low cytotoxicity in the MTT assay, thus are potential candidates for biomedical applications.

Synthesis and properties of amphiphilic hyperbranched polyethers as pigment dispersant

Hyperbranched polymers possess prominent properties such as low viscosity, good solubility, high rheological property, environmental non-toxic, and so on, which have potential applications in coatings. In this study, the amphiphilic hyperbranched polyethers (AHPs) consisting of hydrophobic hyperbranched polyethers core and hydrophilic poly (ethylene glycol) arms with different degree of branching (DB) under various reaction temperatures was prepared by the cation ring-opening polymerization. Their structures were characterized by IR, 13CNMR and GPC. Their dispersion properties for pigment particles were investigated. The AHP47 with 0.47 DB was found to have good dispersion properties for Yellow HGR. This work would provide experimental data and theoretical foundation for the application of hyperbranched polyethers in environmental protection coating.

Effect of branching in hyperbranched alkyd on the performance of alkyd polyurethane coating

ABSTRACTHyperbranched alkyd was synthesized by single‐step approach using trimethylolpropane, mono pentaerythritol as core material, and 2,2‐bis(methylol)propionic acid (DMPA), a combination of dehydrated castor oil fatty acid and coconut oil fatty acid as chain extender. A series of hyperbranched alkyds were prepared at different degree of branching in the alkyd structures by changing the amount of DMPA in the alkyd resin formulation. The resins were characterized by Fourier transform infrared and 1H‐nuclear magnetic resonance (NMR) spectroscopic technique. These hyperbranched alkyds were converted into polyurethane coating after reaction with hexamethylene diisocyanate trimer at a definite ratio in the presence of dibutyltin dilaurate as a catalyst. The effect of branching and polymeric chain entanglement on the glass transition temperature, Tg of the alkyd polyurethane coating (APUC) was studied by differential scanning calorimetry technique. The performance of such APUC in terms of gloss, gloss retention under accelerated QUV radiation, natural outdoor exposed condition, mechanical, and corrosion resistance properties were enhanced with the increase of polymeric chain entanglement, i.e., compactness or higher order of branching in the alkyd resin structure. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45835.

Physicochemical properties and in vitro antidiabetic potential of fibre concentrates from onion by-products

Onion by-products, Paste and Bagasse, were used to produce fibre concentrates (FCs), which were studied for dietary fibre (DF) content, physicochemical properties, effects on glucose adsorption, in vitro glucose diffusion, alpha-amylase activity and starch digestibility. FC dietary fibre was composed of cellulose and pectic polysaccharides with different degree of branching. FCs had lower bulk densities, and higher oil-holding and cation exchange capacities, as well as higher hydration properties, than cellulose. Onion FCs had the desired physicochemical properties as fibre sources or low-calorie bulk ingredients in food applications. Both onion FCs were found to have higher glucose-adsorption capacity than cellulose. The retardation of glucose diffusion by FCs were higher than cellulose. All FCs reduced the glucose production rate by inhibiting alpha-amylase activity, and decreased starch digestibility. The results verified the hypoglycaemic effect and the in vitro antidiabetic potential of onion by-product FCs.

Waterborne carboxyl-terminated hyperbranched oligomer polyester ligand: Synthesis, characterization and chelation with chromium(III)

A series of carboxyl-terminated hyperbranched oligomer polyester (HBP) with different degree of branching (DB) and number average molar mass (M¯n) have been prepared. The molecular structure, degree of branching, molecular mass and its distribution of HBP were investigated by FTIR, 1H NMR, and GPC, respectively. And the coordination number, stability constant and degree of dissociation (α) between HBP and chromium(Ⅲ) were measured via continuous variation method (Job's plot). Experimental results show that the coordination capability between HBP and chromium(Ⅲ) affected by both DB and molecular mass, and the latter plays a decisive role. Moreover HBP outperforms low molecular weight of organic acids (citric acid, acetic acid) and linear polyacrylic acid with similar molecular mass. The coordination number and stability constants of HBP-3 (M¯n = 1713 Da, M¯w/M¯n (PDI) = 1.11 and DB = 0.72) can reach 4 and 6.55e+008, which demonstrated it can be selected as a good ligand to coordination with chromium(Ⅲ). Therefore HBP can be used as chrome auxiliary in chrome tanning to improve the absorption of chromium.

Crystallization behavior of hyperbranched polyethylenes with different degree of branching

ABSTRACTHyperbranched polyethylenes (HBPEs) with different degree of branching (DB) and similar Mn are used to investigate the effect of branch structure on their crystallization behaviors. The crystal structure, isothermal, and non‐isothermal crystallization kinetics of HBPEs are studied by X‐ray diffraction and differential scanning calorimetry. The isothermal crystallization process is analyzed by the Avrami equation while the non‐isothermal crystallization process is analyzed through the Ozawa and Mo methods. The XRD results indicate that the crystallization ability of HBPEs is weakened with the introduction of branch structure, i.e., the crystallinity of HBPEs decreases with the increase of DB, and even tends to zero. The kinetics results of isothermal and non‐isothermal crystallization verify the peculiar effects of DB on the crystallization process of HBPEs. In detail, a little of branch structure can accelerate the crystallization process of HBPEs, however a large number of branch can inhibit it. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44127.

One-pot inimer promoted ROCP synthesis of branched copolyesters using α-hydroxy-γ-butyrolactone as the branching reagent.

ABSTRACTAn array of branched poly(ɛ‐caprolactone)s was successfully synthesized using an one‐pot inimer promoted ring‐opening multibranching copolymerization (ROCP) reaction. The biorenewable, commercially available yet unexploited comonomer and initiator 2‐hydroxy‐γ‐butyrolactone was chosen as the inimer to extend the use of 5‐membered lactones to branched structures and simultaneously avoiding the typical tedious work involved in the inimer preparation. Reactions were carried out both in bulk and in solution using stannous octoate (Sn(Oct)2) as the catalyst. Polymerizations with inimer equivalents varying from 0.01 to 0.2 were conducted which resulted in polymers with a degree of branching ranging from 0.049 to 0.124. Detailed ROCP kinetics of different inimer systems were compared to illustrate the branch formation mechanism. The resulting polymer structures were confirmed by 1H, 13C, and 1H‐13C HSQC NMR and SEC (RI detector and triple detectors). The thermal properties of polymers with different degree of branching were investigated by DSC, confirming the branch formation. Through this work, we have extended the current use of the non‐homopolymerizable γ‐butyrolactone to the branched polymers and thoroughly examined its behaviors in ROCP. © 2016 The Authors. Journal of Polymer Science Part A: Polymer Chemistry Published by Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1908–1918

Effect of branching architecture on glass transition behavior of hyperbranched copolystyrenes: the experiment and simulation studies

By controlling the feed ratio of CMS/styrene and the polymerization time, a series of hyperbranched copolystyrenes (HBCPS) were synthesized with comparable weight-averaged molecular weights (M w) but different degree of branching (DB) through atom transfer radical self-condensing vinyl copolymerization (ATR-SCVCP) with CuBr/2,2′-bipyridyl as the catalyst. The resulting HBCPS samples were used to investigate the effect of branching architecture on their glass transition behavior. With the DB increased, the glass transition temperatures (T g) of HBCPS samples measured by DMA and DSC both decreased. Their spin-lattice relaxation times (1H T 1r) of protons displayed the same downtrend with increasing DB. Besides, a correlation between the T gs and the DB was well established by all-atom molecular dynamics (MD) simulations. The values of MD-determined T gs are little higher than the corresponding experimental ones. However, the dependence of T gs on DB is in good agreement with the experimental results, i.e., T g decreases both in experiments and simulations with increasing DB.

Cure behavior and enhanced thermal properties of benzoxazine thermosets with isocyanate-terminated hyperbranched polyurethane of different degree of branching

In the study, we investigated the influence of degree of branching (DB) of isocyanate-functionalized hyperbranched polyurethanes (HPU–NCOX) on the cure and thermal property of phenol-terminated benzoxazine oligomer (BZ–OH). The structure of the as-synthesized HPU–NCOX was confirmed by proton nuclear magnetic resonance (1H NMR and 13C NMR), gel permeation chromatography (GPC) and Fourier transform infrared spectra (FT-IR). Thermally activated cross-linking behavior as well as the thermal stability of HPU–NCOX/BZ–OH blend was investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). HPU–NCOX can covalently incorporate into BZ–OH via urethane reaction. Both the cure kinetics and the weight residue of HPU–NCOX/BZ–OH copolymer reveal a gradual increase with the improvement of DB of HPU–NCOX. A novel isocyanate-functionalized hyperbranched polyurethanes (HPU–NCOX) with degree of branching (DB) ranging from 25.1 to 51.1 % were successfully synthesized. The HPU–NCOX and benzoxazine copolymers exhibit enhanced cure kinetics with the increase of DB of HPU–NCOX.

Extraction and characterisation of pomace pectin from gold kiwifruit (Actinidia chinensis)

Gold kiwifruit pomace extracted using citric acid, water and enzyme (Celluclast 1.5L) were studied in terms of pectin yield, protein, ash, non-starch polysaccharide, galacturonic acid (GalA), neutral sugar composition, molar mass (Mw), viscosity and degree of branching. Water-extracted pectin was considered closest to its native form. Enzyme extracted pectin showed the highest yield (∼4.5%w/w) as compared with the acid and water extraction methods (∼3.6–3.8%w/w). Pectin obtained from different extraction methods showed different degree of branching. The Mw and root mean square (RMS) radius varied with the extraction methods with values of 8.4×105g/mol and 92nm, 8.5×105g/mol and 102nm, 6.7×105g/mol and 52nm for acid, water and enzymatic extraction methods, respectively. Similar trend was observed for pectin viscosity, with water-extracted pectin giving a slightly higher viscosity followed by acid and enzyme-extracted pectin. This study showed that gold kiwifruit pomace pectin has potential application in food products.

Multi-Scale Simulation of Hyperbranched Polymers

In a previous work, we described a multi-scale protocol for the simulation of the conformation and dynamics of macromolecules that was applied to dendrimer molecules proving its predictive capability by comparison with experimental data. That scheme is now employed in order to predict conformational properties (radius of gyration) and overall hydrodynamic properties (translational diffusion and intrinsic viscosity) of hyperbranched molecules in dilute solution. For that purpose, we use a very simple coarse-grained bead-and-spring model whose parameters are not adjusted against experimental properties but they are obtained from previous atomic-level (Langevin) simulations of small fragments of real hyperbranched polymers. In addition, we devise a method to generate structures with different degree of branching. The Monte Carlo simulation technique was used to generate the set conformations of the coarse-grained model. In spite of the difficulties of reproducing experimental data of highly polydisperse entities (in terms of both molecular weight and topology) without using adjustable parameters, the results of this paper show that the proposed methodology allows for qualitative predictions of the behavior of such complex systems and lead us to conclude that, after some improvement, acceptable quantitative predictions can be achieved.

Optical properties of composites with nanodimensional oxide coatings versus the properties of film-forming sols. I. The influence of sol’s oxide composition

The influence of the aging period (duration) and the aging-related rheological characteristics of film-forming solutions (sols) on the refractive index and thickness of coatings, light reflection and light transmission coefficients, and optical losses in glass substrate-nanodimensional oxide (CuO-TiO2) composites is considered. It has been shown that the increase in the CuO concentration in the coating and the extension of the sol aging period favor crystallization and change the form of inclusions in the coating from pseudospherical to dendritic with a different degree of branching. The refractive index of the film and its related coefficient of mirror reflection of the composite are functions of the density of packing sol disperse-phase particles into a nanodimensional layer. The packing density of dendritic particles drops decreases with the degree of their branching and transverse size of fragments. In every case, an optimal sol aging period should be found to obtain glass composites with nanodimensional coatings offering desired optical properties.

Non-cellulosic heteropolysaccharides from sugarcane bagasse – Sequential extraction with pressurized hot water and alkaline peroxide at different temperatures

The xylan-rich hemicellulose components of sugarcane bagasse were sequentially extracted with pressurized hot-water extraction (PHWE) and alkaline peroxide. The hemicelluloses were found to contain mainly arabinoxylans with varying substitutions confirmed by different chemical and spectroscopic methods. The arabinoxylans obtained from PHWE were found to be more branched compared to those obtained after alkaline extraction. Sequential extraction could be useful for the isolation of hemicelluloses with different degree of branching, molar mass, and functional groups from sugarcane bagasse, which can be of high potential use for various industrial applications.

Correlation of branching structure of mushroom β-glucan with its physiological activities

β-Glucans with a different degree of branching (DB) were prepared from three different mushrooms and their physiological properties were characterized in terms of branching structure. β-Glucan with 29% DB from shitake mushroom was the most effective in inhibiting the growth of tumor cells and also producing nitric oxide compared to Chamsong-I (67% DB) and cauliflower (16% DB) β-glucan. In addition, the β-(1-6)-linked branches of β-glucan from Chamsong-I mushroom were specifically hydrolyzed by enzymatic treatments to produce β-glucan samples with various DB from 19 to 50%. As the DB of β-glucan reduced, the inhibition of cancer cell growth and production of nitric oxide increased when the branching reached up to 32%, then decreased as the DB further reduced. Therefore, these results indicated that the branching structure of β-glucan plays a crucial role in its antitumor effect and the antitumor effect could be enhanced by modulating critical branching structure of β-glucan.