Hydrophilic-hydrophobic Ratio Research Articles

Characterization and emulsifying ability evaluation of whey protein-pectin conjugates formed by glycosylation

Glycosylation is a method that enhances the functional properties of proteins by covalently attaching sugars to them. This study aimed at preparing three conjugates (WP-HG, WP-SBP, and WP-RGI) by dry heating method to research the influence of different pectin structures on the functional properties of WP and characterize properties and structures of these conjugates. The research results manifested that the degree of glycosylation (DG) of HG, SBP and RGI were 13.13 % ± 0.07 %, 23.27 % ± 0.3 % and 36.39 % ± 0.3 % respectively, suggesting that the increase of the number of branch chains promoted the glycosylation reaction. The formation of the conjugate was identified by the FT-IR spectroscopy technique. And SEM showed that WP could covalently bind to pectin, resulting in a smoother and denser surface of the conjugates. The circular dichroism analysis exhibited that the glycosylation reaction altered the secondary structure of WP and decreased the α-Helix content. This structural change in the protein spatial conformation led to a decrease in the hydrophobicity of protein surface. But the addition of pectin further regulated the hydrophilic-hydrophobic ratio on the surface of the protein, thus improving the emulsification properties of WP. In addition, the glycosylation could improve the stability of the emulsion, giving it a smaller droplet size, higher Zeta-potential and more stable properties. In a word, this study pointed out the direction for the application of different pectin structures in the development of functional properties of glycosylation products in food ingredients.

Amphiphilic Balance: Effect of the Hydrophilic-Hydrophobic Ratio on Fouling-Release Surfaces.

This study demonstrated the importance of identifying the optimal balance of hydrophilic and hydrophobic moieties in amphiphilic coatings to achieve fouling-release (FR) performance that surpasses that of traditional hydrophobic marine coatings. While there have been many reports on fouling-release properties of amphiphilic surfaces, the offered understanding is often limited. Hence, this work is focused on further understanding of the amphiphilic surfaces. Poly(ethylene glycol) (PEG) and polydimethylsiloxane (PDMS) were used to create a series of noncross-linked amphiphilic additives that were then added to a hydrophobic-designed siloxane-polyurethane (SiPU) FR system. After being characterized by ATR-FTIR, XPS, contact angle analysis, and AFM, the FR performance was evaluated by using different marine organisms. The assessments showed that the closer the hydrophilic and hydrophobic moieties in a system reached a relatively equalized level, the more desirable the FR performance of the coating system became. A balanced ratio of hydrophilicity-hydrophobicity in the system at around 10-15 wt % of each component had the best FR performance and was comparable to or better than commercial FR coatings.

The influence of cone structure and wettability on vaporization nucleation

Surface wettability and surface structure are critical factors that affect vaporization nucleation. However, their coupling effects on nucleation have yet to be thoroughly studied. This study employs molecular dynamics (MD) techniques to investigate the impact of nanostructures and walls with varying wettability on vaporization nucleation. Theoretical analysis verification demonstrate that increasing the hydrophobic ratio of the hybrid wall or adding a cone structure to the wall reduces the vaporization nucleation time.Previous studies did not separate the “surface area” and “cone height” factors when examining the relationship between cone surface structure and boiling. In this work, we analyzed the factors that affect vaporization nucleation. We found that increased surface area shortens nucleation time, and when the surface area is the same, higher cone heights lead to shorter nucleation times. Additionally, we examined the coupling effect of surface structure and wettability on nucleation. The results indicate that an increased proportion of hydrophobic walls with identical surface structures enhances the likelihood of nucleation. Furthermore, hydrophilic wall-hydrophobic cones with the same hydrophilic-hydrophobic ratio are more prone to nucleation than hydrophobic wall-hydrophilic cones. These findings provide insights into the design of nanostructures to enhance heat transfer involving boiling.

Regulation Mechanism of Bubbling Deformation and Fracture Toughness of the Membrane by Asymmetric Phospholipids: A Model System Study.

Dynamic regulation of the deformation modulus and fracture toughness of a membrane is critical to organelles and cells for matching their conflicting needs of resilient and fractured behaviors. These properties implement the protection of the function in the normal condition and the fission function in the endocytosis condition of a membrane. Naturally, a membrane contains phospholipids that have different hydrophilic and hydrophobic group length. The diffusion and aggregation of the phospholipids with asymmetry of the hydrophilic-hydrophobic ratio on the membrane play a key role in regulating the mechanical behaviors passively to the external force. In present work, the effects of the asymmetry of phospholipids on the bubbling deformation and fracture toughness of the membrane to external stretching are investigated in a model system. A disk-shaped micelle formed from the blend of symmetric and asymmetric diblock copolymers in a selective solvent is considered as the membrane sheet. Its mechanically responsive behaviors are investigated by self-consistent field theory. By analyzing the evolution of different components during the stretching process, the mechanism of formation of the bubbling structure is revealed. Moreover, the fracture toughness depending on the asymmetry of the phospholipids is determined quantitatively.

Effect of hydrophilic-hydrophobic ratio in self-emulsifying amphiphilic epoxy sizing agent on interfacial properties of carbon fibre/epoxy composites

More and more attention has been paid to the synthesis and characterization of self-emulsifying sizing agents without organic solvent due to the demand of environment-friendless. Herein, self-emulsifying amphiphilic epoxy sizing agents with different hydrophilic-hydrophobic ratios were synthesized and used to enhance interfacial adhesion between carbon fibre (CF) and epoxy resin (EP). The effects of hydrophilic-hydrophobic ratio on the characteristics of sizing agent emulsion, the wettability and morphology of sized CFs, the monofilament CF tensile strength and the interfacial shear strength (IFSS) of CF/EP were investigated. The results showed that the emulsions were mono-dispersed nanospheres and the particle size was increased with the hydrophobic groups increasing. High thermal stability with negligible weight loss unless well above 300℃ was obtained for all the emulsions. The sized CFs by the emulsions of high hydrophobic ratio (9:1 and 19:1) exhibited more favorable wettability. The CF surface defects were healed and the roughness was reduced mildly by sizing treatment. The IFSS showed a growing trend with the hydrophobic groups increasing and was significantly enhanced by 96 % as the hydrophilic-hydrophobic ratio was 19:1. The improvement of IFSS benefited mainly from the strong interphase due to the excellent film-forming property, favorable wettability and mechanical interlocking.

Construction of nanostructures in aqueous solution from amphiphilic glucose‐derived polycarbonates

ABSTRACTCarbohydrates are the fundamental building blocks of many natural polymers, their wide bioavailability, high chemical functionality, and stereochemical diversity make them attractive starting materials for the development of new synthetic polymers. In this work, one such carbohydrate, d‐glucopyranoside, was utilized to produce a hydrophobic five‐membered cyclic carbonate monomer to afford sugar‐based amphiphilic copolymers and block copolymers via organocatalyzed ring‐opening polymerizations with 4‐methylbenzyl alcohol and methoxy poly(ethylene glycol) as initiator and macroinitiator, respectively. To modulate the amphiphilicities of these polymers acidic benzylidene cleavage reactions were performed to deprotect the sugar repeat units and present hydrophilic hydroxyl side chain groups. Assembly of the polymers under aqueous conditions revealed interesting morphological differences, based on the polymer molar mass and repeat unit composition. The initial polymers, prior to the removal of the benzylidenes, underwent a morphological change from micelles to vesicles as the sugar block length was increased, causing a decrease in the hydrophilic–hydrophobic ratio. Deprotection of the sugar block increased the hydrophilicity and gave micellar morphologies. This tunable polymeric platform holds promise for the production of advanced materials for implementation in a diverse range of applications. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 432–440

Tuning the Selectivity of Biodegradable Antimicrobial Cationic Polycarbonates by Exchanging the Counter-Anion.

There is a growing interest in modern healthcare to develop systems able to fight antibiotic resistant bacteria. Antimicrobial cationic biodegradable polymers able to mimic antimicrobial peptides have shown to be effective against both Gram-positive and Gram-negative bacteria. In these systems, the hydrophilic-hydrophobic ratio and the cationic charge density play a pivotal role in defining the killing efficiency. Nevertheless, many of these antimicrobial polymers show relatively low selectivity as defined by the relative toxicity to mammalian cells or hemolysis relative to pathogens. In this study, a series of polycarbonates containing pendant quaternary ammoniums are used to understand the role of different counter-anions including chloride, citrate, malonate, benzoate, acetate, lactate and trifluoroacetate, and the antibiotic penicillin on antimicrobial efficacy and selectivity. Interestingly, it is found that in spite of the strong antimicrobial activity of trifluoroacetate and benzoate anions, they prove to be much less hemolytic than chloride anion. It is believed that the proper selection of the anion could enhance the potential of antimicrobial polymers to fight against clinically relevant pathogenic infections, while concurrently mitigating harmful side effects.

Crystal structure model based on the analysis of hydrophilic-hydrophobic ratio in molecules. Isosteviol derivatives

In the context of an earlier suggested model for the crystal structure description, based on the phenomenon of localization in the crystals of hydrophilic and hydrophobic regions, the comparative analysis of crystal packing and supramolecular structure in a series of isosteviol derivatives and their analogs, available in Cambridge Structural Database, was carried out. It was found that the observed in the crystals separation of hydrophilic and hydrophobic regions may be considered in frame of the theory of microphase separation in block copolymers, and the type of forming supramolecular structures depends on the ratio of volumes of hydrophilic and hydrophobic molecular fragments. Basing on the XRD data obtained for steviol bioside, possibilities for the prediction of morphology type of molecular packing in crystals using the calculations of hydrophobic-hydrophilic ratio are demonstrated.

Studies on apparent molar volumes and heat capacities of several pluronics (triblock copolymers) in aqueous solutions of sodium dodecyl sulfate at 298.15 and 318.15 KElectronic supplementary information (ESI) available: Apparent molar properties of SDS in aqueous pluronic solutions at 298.15 and 318.15 K. See http://www.rsc.org/suppdata/cp/b3/b313717a/

Density and heat capacity measurements were performed in order to investigate the interactions between the ionic surfactant sodium dodecyl sulfate (SDS) and some triblock copolymers of poly(ethylene oxide) and poly(propylene oxide), at 298.15 and 318.15 K. The pluronics L31, L35, 10R5, L64, F68 and P123, were selected as copolymers because of their convenient hydrophilic-hydrophobic ratio and critical micellar temperature. Molar volumes and heat capacities of transfer of either SDS or copolymer from water to an aqueous mixed solution were calculated from the density and heat capacity values and analysed as a function of the surfactant concentration. It was found that the transfer properties depend mainly on the state of the copolymers. For the unassociated copolymers, the molar volumes of transfer of both SDS and copolymer are positive. The initial sharp increase seen in the corresponding plots against surfactant molality signals the formation of a surfactant-copolymer complex up to the saturation of the copolymer. Thereafter, the constant values of transfer volumes of copolymers depend mainly on the length of the poly(propylene oxide) block. For the associated copolymers, negative volumes of transfer of either SDS or copolymer were observed. They are ascribed to interactions between SDS and copolymer micelles that give rise to a rapid breakdown of the aggregates. The profiles of the transfer heat capacity curves show more complicated trends through the critical micellar concentration region, which are interpreted as being due to the large positive contribution of the relaxation terms related to the equilibrium shifts induced by the temperature.