Influence Of Chain Length Research Articles

Evolution of Statistical Strength during the Contact of Amorphous Polymer Specimens below the Glass Transition Temperature: Influence of Chain Length.

A comprehensive study of the statistical distribution of the auto-adhesion lap-shear strength (σ) of amorphous polymer-polymer interfaces using various types of statistical tests and models is a useful approach aimed at a better understanding of the mechanisms of the self-healing interface. In the present work, this approach has been applied, for the first time, to a temperature (T) range below the bulk glass transition temperature (Tgbulk). The interest of this T range consists in a very limited or even frozen translational segmental motion giving little or no chance for adhesion to occur. To clarify this issue, the two identical samples of entangled amorphous polystyrene (PS) with a molecular weight (M) of 105 g/mol or 106 g/mol were kept in contact at T = Tgbulk - 33 °C for one day. The as-self-bonded PS-PS auto-adhesive joints (AJ) of PSs differing in M by an order of magnitude were fractured at ambient temperature, and their σ distributions were analyzed using the Weibull model, the quantile-quantile plots, the normality tests, and the Gaussian distribution. It has been shown that the Weibull model most correctly describes the σ statistical distributions of the two self-bonded PS-PS AJs with different M due to the joints' brittleness. The values of the Weibull modulus (a statistical parameter) m = 2.40 and 1.89 calculated for PSs with M = 105 and 106 g/mol, respectively, were rather close, indicating that the chain length has a minor effect on the σ data scatter. The Gaussian distribution has been found to be less appropriate for this purpose, though all the normality tests performed have predicted the correctness of the normal distribution for these PS-PS interfaces.

Influence of alkyl chain length on the photovoltaic properties of dithienopyran-based hole-transporting materials for perovskite solar cells

A tailored design of asymmetric hole-transporting materials (HTMs) is reported with the synthesis of a family of new HTMs based on the use of the 5H-dithieno[3,2-b:2′,3′-d]pyran (DTP) moiety endowed with donor p-methoxytriphenylamines.

Influence of Hydrophobic and Hydrophilic Chain Length of CiEj Surfactants on the Solubilization of Active Pharmaceutical Ingredients.

Up to 90% of all newly developed active pharmaceutical ingredients (APIs) are poorly water soluble, most likely also showing a low oral bioavailability. In order to increase the aqueous solubility of these APIs, surfactants are promising excipients to increase both solubility and consequently bioavailability (e.g., in lipid- and surfactant-based drug delivery systems). In this work, we investigated the influence of hydrophobic and hydrophilic chain lengths of CiEj surfactants (C8E6, C10E6, and C10E8) toward the solubilization of fenofibrate, naproxen, and lidocaine. Furthermore, we investigated the partitioning of these APIs between the surfactant aggregates and the surrounding aqueous bulk phase. For all APIs considered, we determined the locus of API solubilization as well as the individual aggregation numbers (Nagg) of surfactants and API molecules in an API/surfactant aggregate. We further determined the hydrodynamic radius (Rh) of the API/surfactant aggregates in the absence and presence of the APIs. The size of the API/surfactant aggregates (Nagg, Rh) passes through a minimum upon lidocaine solubilization; it gradually increases upon naproxen solubilization and is almost constant upon fenofibrate solubilization. The results give valuable insights into the solubilization mechanisms of APIs in the CiEj surfactant aggregates. Our results reveal that fenofibrate is solely solubilized in the hydrophobic core of the CiEj surfactant aggregates, as only the hydrophobic chain length of the surfactant influences its solubilization. Naproxen is solubilized in the palisade layer of the surfactant aggregates, as both the hydrophobic and hydrophilic chain lengths are decisive for its solubilization. Lidocaine is mainly solubilized in the rather hydrophilic corona region of the surfactant aggregates, as the hydrophilic chain length of the surfactant governs its solubilization. The results further reveal that the hydrophilic/lipophilic balance is not an appropriate measure to estimate the solubilization capacity of surfactant aggregates.

Bioaccumulation and Biotransformation of Chlorinated Paraffins.

Chlorinated paraffins (CPs), a class of persistent, toxic, and bioaccumulated compounds, have received increasing attention for their environmental occurrence and ecological and human health risks worldwide in the past decades. Understanding the environmental behavior and fate of CPs faces a huge challenge owing to the extremely complex CP congeners. Consequently, the aims of the present study are to summarize and integrate the bioaccumulation and biotransformation of CPs, including the occurrence of CPs in biota, tissue distribution, biomagnification, and trophic transfer, and biotransformation of CPs in plants, invertebrates, and vertebrates in detail. Biota samples collected in China showed higher CP concentrations than other regions, which is consistent with their huge production and usage. The lipid content is the major factor that determines the physical burden of CPs in tissues or organs. Regarding the bioaccumulation of CPs and their influence factors, inconsistent results were obtained. Biotransformation is an important reason for this variable. Some CP congeners are readily biodegradable in plants, animals, and microorganisms. Hydroxylation, dechlorination, chlorine rearrangement, and carbon chain decomposition are potential biotransformation pathways for the CP congeners. Knowledge of the influence of chain length, chlorination degree, constitution, and stereochemistry on the tissue distribution, bioaccumulation, and biotransformation is still scarce.

Polysiloxane-based Electrolytes: Influence of Salt Type and Polymer Chain Length on the Physical and Electrochemical Properties.

An oligo/poly(methyl(2-(tris(2-H methoxyethoxy)silyl)ethyl)siloxane)), 390EO, and 2550EO, were synthesized. Dilute electrolyte solutions of 390EO and 2550EO were prepared using LiTFSI, LiFSI, and LiPF6 . The influence of the length of the siloxane polymer chain, salt type, and Si-tripodand centers at the side chain on ionic conductivity, tLi + , and physical properties were examined. Both electrolyte systems showed high values of tLi + (0.35 for 2550EO/LiTFSI and 0.64 for 390EO/LiTFSI). Alternatively 390EO/LiPF6 and 2550EO/LiPF6 displayed high tLi + values of 0.61 and 0.44, respectively, while 390EO/LiFSI displayed the smallest tLi+ (0.25). To clarify the role played by the Li+ environment in Li+ transport, the solvation states of electrolytes were examined. It was observed that anion solvation can be achieved using siloxane-based solvent in all systems. Walden plot analysis demonstrates that ionic diffusion was not controlled by either macroviscosity/microviscosity in the siloxane-based polymer electrolytes. Ions instead move along a relatively smooth ion-pathway without complete full segmental reorientation in 2550EO as a result of decoupling and high ion solvation behavior. Conversely, in 390EO, ions might move to available sites by a jumping after decoupling with low ion solvation behavior. Consequently, a high t Li + was achieved, and the oxidative stability of the salt was ensured.

Understanding the Molecular Features Controlling the Solubility Differences of R-134a, R-1234ze(E), and R-1234yf in 1-Alkyl-3-methylimidazolium Tricyanomethanide Ionic Liquids

This work reports a study of the absorption of fluorinated refrigerant gases in ionic liquids (ILs) from a combined experimental and computational approach to gain insights into the solvation of these greenhouse gases. The results allow the selection of solvents for fluorinated gas recovery, based on molecular characteristics, and improve the recyclability of these high-value-added compounds. The solubility of R-134a, R-1234yf, and R-1234ze(E) was measured experimentally in 1-alkyl-3-methylimidazolium tricyanomethanide ILs at 283.15–323.15 K and up to 5 bar to investigate the influence of the alkyl side chain length of the cations in the ILs. Molecular dynamics was used to study solvation environments around refrigerant molecules in terms of radial distribution functions, coordination numbers, and spatial distribution functions. Simulations were carried out with the recent CL&Pol polarizable force field for ILs, which includes polarization effects explicitly. The force field was validated against experimental solubility through free-energy perturbation calculations. The main effects influencing the solubility of fluorinated refrigerants in ILs result from interactions with the anions and with the cation head group alkyl chain, setting a basis for a rational selection and design of ILs for processes to recover and recycle refrigerants in a circular economy model.

Probing the influence of alkyl chain length on the aggregation behaviour of some naphthalene sulphonamide derivatives through spectroscopic and microscopic studies

With an aim to understand the role of alkyl chain length in tuning the optical properties of the organic aggregates, several naphthalene sulphonamide derivatives with different alkyl chain lengths have been synthesized. Molecular systems are used to fabricate different aggregates. Aggregation behaviour of the systems has been investigated by exploiting spectroscopic and microscopic technique. Investigations have revealed that the aggregates formed by shorter alkyl chain containing derivatives exhibit blue-shifted absorption and emission (as compared to respective monomer) to form H-aggregate whereas longer alkyl chain containing derivatives exhibit red-shifted absorption and emission (as compared to respective monomer) to form J-aggregate.

Influence of the Alkyl Side Chain Length on the Assembly and Thermochromic Solid-State Properties in Symmetric and Asymmetric Monoalkoxynaphthalene–Naphthalimide Donor–Acceptor Dyads

We have been investigating monoalkoxynaphthalene–naphthalimide (MAN–NI) donor–acceptor dyads that undergo a unique and dramatic orange-to-yellow thermochromic transition in the solid state. This study reports a new series of these stimuli-responsive solids, based on dyads with symmetric and relatively long alkyl side chains, as well as asymmetric derivatives. The length of the alkyl side chains influenced the structures, properties, and dynamic behavior of the resulting solids. All of the symmetric alkyl side chain derivatives can crystallize with identical packing (allowing for alkyl chain length differences) in a lasagna-like fashion with alternating alkyl and stacked aromatic layers. The fully extended alkyl side chains are aligned in an interdigitated, “cork and bottle” fashion. The aromatic layers feature head-to-head stacking geometries of the aromatic dyad cores. The crystalline solids derived from each of these derivatives undergo dramatic thermochromic orange-to-yellow transition in the solid state. Crystal structures were obtained for three of the four asymmetric dyad derivatives. In each case, layered structures were observed, although the mismatch in alkyl side chain lengths results in a unique hybrid alkyl/aromatic layer. Two of the asymmetric derivatives exhibit almost identical head-to-head dyad core stacking geometries, while one exhibits a head-to-tail dyad core stacking geometry. Of the four asymmetric dyads studied, only two asymmetric derivatives with the longer alkyl side chains exhibit dynamic solid-state behavior. Overall, our results demonstrate the relatively general nature of the thermochromic orange-to-yellow color-changing mechanism of the MAN–NI dyads and verify the link between the alkyl side chain interactions and this interesting stimuli-responsive behavior in the solid-state.

Insights from computational analysis: Excited-state hydrogen-bonding interactions and ESIPT processes in phenothiazine derivatives

Organic materials with Mechanofluorochromism (MFC) properties have potential application value. Phenothiazine derivatives are a class of substances with MFC properties that have been synthesized and reported in experiments (Dyes and Pigments 172 (2020) 107835). Dual fluorescence of a series of phenothiazine derivatives is observed in the experiment, which proved that the ESIPT process is carried out. In this work, we choose phenothiazine derivatives (C2PAHN, C4PAHN, C8PAHN) as models to theoretically analyze the influence of different alkyl chain lengths on the excited state intramolecular proton transfer (ESIPT). In addition, the shift value of fluorescence spectrum is related to the length of alkyl chain. The fluorescence shift of C2PAHN is the largest (6.31 nm), and that of C8PAHN is the smallest (2.40 nm). The theory of density functional theory (DFT) and time-dependent density functional theory (TD-DFT) are adopted to simulate the molecular dynamics in the ground state and excited state. The analysis of the optimized molecular geometry parameters and infrared vibrational spectroscopy (IR) illustrate the stronger hydrogen bonding of the excited state molecules, which is favorable for the progress of ESIPT. Fluorescence spectroscopy reveals that the appropriate increase or decrease of alkyl chains would change the photophysical properties of the molecules. Frontier molecular orbitals (FMOs) indicate that the rearrangement of electron density from electronic level to is the driving force of the ESIPT process. Reduction density gradient (RDG) surfaces and Natural Population Analysis (NPA) tentatively lead to the conclusion that alkyl chain length is inversely proportional to hydrogen bond strength. Finally, the data are qualitatively analyzed by scanning the potential energy curves, and it is concluded that the longer the alkyl chain, the weaker the hydrogen bonding effect and the more unfavorable the ESIPT process.

Alkyl chain length influence of hydrotrope on the pH responsiveness of surfactant aggregates based on dynamic imine bond

• Ionic hydrotropes with different chain length based on imine bond is prepared. • The pH responsiveness of solution by mixing CTAB and hydrotrope is explored. • The mechanism of different pH responsiveness of mixture is analyzed. The combination of pH-responsive hydrotropes and cationic surfactants is a novel way to construct pH-responsive surfactant aggregates. Herein, in order to investigate the chain length influence of hydrotrope on surfactant aggregate, three hydrotropes were formed from p-hydroxybenzaldehyde (HB) and added amine (hexylamine (HA), octylamine (OA), dodecylamine (DA)) respectively based on dynamic imine bonds. Then the surfactant aggregates were constructed by adding cetyltrimethyl ammonium bromide (CTAB). The molar ratio of CTAB: HB: HA/OA/DA was fixed at 100:55:55. The formation of imine bonds was proved by means of 1 H NMR measurement. Rheological measurements, and cryo -TEM were used to explore the pH responsiveness of the surfactant aggregates. The results showed that as pH increased from 6.0 to 12.0, the CTAB/HB/HA system changed from a low viscosity fluid to a viscoelastic fluid, as the CTAB/HB/OA system transformed from aqueous liquid via a transparent gel solution to a turbid fluid. On the other hand, the CTAB/HB/DA system can achieve four state transitions, from a non-viscosity fluid, via a viscoelastic fluid, turbid fluid and finally to a viscoelastic fluid. With the change of pH, the CTAB/HB/HA system turned from spherical to wormlike micelles, while CTAB/HB/OA experienced changes from spherical micelles via wormlike micelles to vesicles. Finally, the CTAB/HB/DA system was the most complex one, which converted from spherical micelles, wormlike micelles via vesicle, into final wormlike micelles. In conclusion, the sensitivity of pH responsiveness among these three systems gradually improved by increasing the chain length of the hydrotrope formed by HB and amine. This can be attributed to the different growth rates of the packing parameter. This work demonstrated the feasibility of constructing pH responsive surfactant aggregates by introducing hydrotropes to cationic surfactants.

Effects of length and type of the alkyl chain on the micellization behavior of mixed systems of HS15 with fatty acids

Due to volatility, low solubility and instability, the application of SCFAs and MCFAs is limited, which is expected to be solved by micelles. Taking SCFAs and MCFAs as models, this paper aims to research the influences of alkyl chain length and type on HS15 micelles. The critical micelle concentration (CMC) of various acid-HS15 systems was determined firstly. Then some air–water interface parameters and thermodynamic parameters were analyzed. Subsequently, particle size, cloud points (CP) and fluorophore release curves were measured. With the increase of CMC and Gmin, the decrease of size and CP, and the rapid quenching of fluorophores, it is more difficult for acids with longer-chain to form stable micelles with HS15 because of the strength of iceberg structure. Showing smaller CMC and Gmin, smaller size, higher CP and slower release of fluorescers, branched molecules can bind more closely to the hydrophobic part of HS15 due to their spatial flexibility.

Influence of chain length on the anticancer activity of the antimicrobial peptide CAMEL with fatty acid modification

Antimicrobial peptides (AMPs) display promising potential in cancer therapy. Modification with fatty acids is a simple and effective approach to improve the activity of AMPs. In the present study, we investigated the effects of fatty acid chain lengths on the anticancer activity, self-assembly and mechanism of action of CAMEL (CM15, KWKLFKKIGAVLKVL-NH2), an amphipathic AMP with 15 amino acids. Conjugation of fatty acids could obviously improve the in vitro anticancer activity of CAMEL. Among the tested peptides, C12-CAMEL showed the highest anticancer activity, while C16-CAMEL killed cancer cells with the slowest kinetics. This may be related to the self-assembly of C12-CAMEL and C16-CAMEL, which could form spherical nanoparticles and tightened nanofibers, respectively. In addition, necrosis and necroptosis rather than apoptosis were the major mechanisms underlying the anticancer activity of CAMEL, C12-CAMEL and C16-CAMEL, implying that modification with fatty acids did not obviously alter the mechanism of action of CAMEL. Notably, C12-CAMEL, with high and rapid cell-killing activity, exhibited significantly stronger in vivo anticancer activity than CAMEL and C16-CAMEL. Overall, the present work suggests that the choice of a suitable fatty acid for structural modification is necessary for improving the anticancer activity of AMPs.

Influence of Aliphatic Chain Length on Structural, Thermal and Electrochemical Properties of n-alkylene Benzyl Alcohols: A Study of the Odd-Even Effect.

The century-old, well-known odd–even effect phenomenon is still a very attractive and intriguing topic in supramolecular and nano-scale organic chemistry. As a part of our continuous efforts in the study of supramolecular chemistry, we have prepared three novel aromatic alcohols (1,2-bis[2-(hydroxymethyl)phenoxy]butylene (Do4OH), 1,2-bis[2-(hydroxymethyl)phenoxy]pentylene (Do5OH) and 1,2-bis[2-(hydroxymethyl)phenoxy]hexylene (Do6OH)) and determined their crystal and molecular structures by single-crystal X-ray diffraction. In all compounds, two benzyl alcohol groups are linked by an aliphatic chain of different lengths (CH2)n; n = 4, 5 and 6. The major differences in the molecular structures were found in the overall planarity of the molecules and the conformation of the aliphatic chain. Molecules with an even number of CH2 groups tend to be planar with an all-trans conformation of the aliphatic chain, while the odd-numbered molecule is non-planar, with partial gauche conformation. A direct consequence of these structural differences is visible in the melting points—odd-numbered compounds of a particular series display systematically lower melting points. Crystal and molecular structures were additionally studied by the theoretical calculations and the melting points were correlated with packing density and the number of CH2 groups. The results have shown that the generally accepted rule, higher density = higher stability = higher melting point, could not be applied to these compounds. It was found that the denser packaging causes an increase in the percentage of repulsive H‧‧‧H interactions, thereby reducing the stability of the crystal, and consequently, the melting points. Another interesting consequence of different molecular structures is their electrochemical and antioxidative properties—a non-planar structure displays the highest oxidation peak of hydroxyl groups and moderate antioxidant activity.

Preparation of Zein-Based Nanoparticles: Nanoprecipitation versus Microfluidic-Assisted Manufacture, Effects of PEGylation on Nanoparticle Characteristics and Cellular Uptake by Melanoma Cells

BackgroundThe manufacture of nanoparticles using manual methods is hampered by its challenging scale-up and poor reproducibility. To overcome this issue, the production of zein nanoparticles entrapping a lipophilic drug model, coumarin-6, by using a microfluidic system was assessed in this study. The influence of PEG density and chain length on zein nanoparticle characteristics, as well as their uptake efficacy in melanoma cancer cells, was also evaluated.MethodsZein nanoparticles were prepared by both manual and microfluidic approaches to allow comparison between the two processes. PEGylated zein nanoparticles with various PEG densities and chain lengths were produced by nanoprecipitation and characterized. Their cellular uptake was evaluated on B16F10 melanoma cancer cells in vitro.ResultsZein nanoparticles have successfully been produced by both manual and microfluidic approaches. Parameters such as total flow rate and flow rate ratio of the aqueous and organic phases in microfluidic process, as well as the method preparation and aqueous to organic phase volume ratio during nanoprecipitation, have been shown to strongly influence the characteristics of the resulting nanoparticles. Continuous microfluidics led to the production of nanoparticles with low yield and drug entrapment, unlike nanoprecipitation, which resulted in zein nanoparticles with an appropriate size and an optimal drug entrapment efficiency of 64%. The surface modification of the nanoparticles produced by nanoprecipitation, with lower PEG density and shorter PEG chain length made mPEG5K-zein (0.5:1) the most favorable formulation in our study, resulting in enhanced stability and higher coumarin-6 uptake by melanoma cancer cells.ConclusionmPEG5K-zein (0.5:1) nanoparticles prepared by nanoprecipitation were the most promising formulation in our study, exhibiting increased stability and enhancing coumarin-6 uptake by melanoma cancer cells.

Influences of nanoparticles and chain length on thermodynamic and electrical behavior of fluorine liquid crystals

Hydrogen-bonded polar nematic liquid crystal series with the general formula nOBAF (n = 7–12) is studied. The mesomorphic characterization is demonstrated through differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The complexes with short alkyl chains (n = 7, 8) present a wide nematic range and monotropic smectic F mesophase, whereas the longer alkyl chain (n = 10–12) analogues show high melting and low clearing mesomorphic liquid crystals. The thermal range of the mesophase and the birefringence increase with chain length decreasing. Furthermore, the effect of the nanoparticles (LiNbO3) on the thermal and the electrical behavior of 8OBAF are investigated. The presence of LiNbO3 nanoparticles increases the conductivity and reduces the resistivity of the complex.

Both alkyl chain length and V-amylose structure affect the structural and digestive stability of amylose-alkylresorcinols inclusion complexes

Alkylresorcinols (ARs) are a group of bioactive phenolic lipids and mostly concentrated in the bran of whole grains. In this study, the influences of alkyl chain length of ARs and V-amylose structure on the stability of V-amylose-ARs inclusion complexes were characterized. On the one hand, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and in vitro digestion studies of complexes showed that the crystallinity, thermo-stability, and digestion resistance of V-amylose-ARs inclusion complexes increased with increasing alkyl chain length of ARs. On the other hand, V6-amylose-ARs inclusion complexes displayed the strongest thermostability, the highest crystallinity, and the lowest digestibility compared to V7-amylose-ARs inclusion complexes and V8-amylose-ARs inclusion complexes. It could be concluded that both the helical structure of hydrated V6-amylose and ARs with longer alkyl chain stabilized the structure and stability of the inclusion complexes. This work could pave a way to develop bioactive cereal foods with high bioaccessibility of ARs.

Effect of stabilization and fatty acids chain length on the crystallization behavior of interesterified blends during storage

In this work, we studied the influence of fatty acid chain length and crystallization temperature on the crystallization behavior during the storage of binary blends modified by chemical interesterification. The blends were produced with soybean oil and fully hydrogenated oils from palm kernel, palm, soybean, microalgae, and crambe, evaluated separately, at a ratio of 50:50 (% w/w). The blends were crystallized by two crystalline stabilization methods. In method I, the samples were maintained at 25 °C for 24 h before the analyses. In method II, the samples were maintained at 5 °C for 24 h, followed by crystalline stabilization at 25 °C for 24 h before the analyses. The interesterification reaction caused considerable changes in the TAGs profile with increasing asymmetric TAGs. These TAGs changes promoted an increase in the crystallization induction time, a decrease in the maximum solids content, and changes in crystals morphology. The increase in the FAs chain length promoted the increased nucleation rate that influenced morphology crystals. Method II promoted a reduction in the medium diameter of crystals and the appearance of the β phase with storage time. For crystallization carried out at higher temperatures (method I), we observed that β’ was favored. Unusual polymorphic transitions were observed with storage time in samples with higher tristearin content. We identified clear correlations between the predominance of β’ phase in the interesterified blends and TAGs of S2U and SU2-type. In addition, the blends with a more diverse range of fatty acids concerning chain size also showed the β’ polymorph. β polymorph, on the other hand, was associated with symmetric TAGs, S3 and U3, and CN-54 type TAG. In this study, we used the Rietveld method to quantify the polymorphs and amorphous content in the blends before and after the randomization reaction. This approach allowed a deeper understanding of the crystalline behavior in the blends, which would be difficult to achieve by performing only a visual analysis of the X-ray diffractograms.

Elucidating degradation mechanisms for a range of per- and polyfluoroalkyl substances (PFAS) via controlled irradiation studies

Per- and polyfluoroalkyl substances (PFAS) are a challenging class of environmental pollutants due to a lack of available destructive remediation technologies. Understanding the fundamental mechanisms for degradation of PFAS is key for the development of field scalable and in-situ destructive based remediation technologies. This study aimed to elucidate and refine the current understanding of PFAS degradation mechanisms in water through a series of controlled gamma irradiation studies. Gamma irradiation of PFAS was performed using a cobalt-60 source in a batch irradiation up to 80 kGy at the Australian Nuclear Science and Technology Organisation. Perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), 6:2 fluorotelomer sulfonate (6:2 FTS), and a suite of thirteen different PFAS (including C4-C12 PFCAs, C4, C6, C8 PFSAs, and FOSA) were irradiated to investigate degradation, influence of pH, chain length, and transformation. High resolution mass spectrometry was used to identify more than 80 fluorinated transformation products throughout the degradation experiments. These included the −F/+H, −F/+OH, −F/CH2OH exchanged PFAS and n − 1 PFCA, amongst others. Given the reactive species present (hydroxyl radicals (·OH), hydrogen radicals (·H) and aqueous electrons (e−aq)), and the degradation products formed it was shown that aqueous electrons were the key reactive species responsible for initial PFAS degradation. Most importantly, based on degradation product formation, we found that the initial −F/+H does not have to occur at the α-fluoride (nearest the functional head group), rather occurring throughout the chain length leading to more complex degradation pathways than previously postulated. While our results support some of the reaction steps postulated in the literature, we have developed a unified 16 step and 3 pathway schematic of degradation supported by experimental observations.

The influence of tail chain length on oil film detachment: C2nTAB series (n = 4 − 9)

Employing molecular dynamic simulations, the detachment process of oil film from silica surface in six cationic surfactants with same head group and different alkyl tail length was investigated. In this work, the surfactant C2nTAB series (n = 4 − 9) were selected to investigate the effect of tail chain length on oil detachment capability. In all surfactants systems, the oil film detachment processes undergone three stages: at initial stage, the surfactants adsorb on the oil-water interface. And then water molecules penetrate the oil film and form a water channel. At last stage, the water molecules spread on the silica surface and the oil film are detached gradually. Quantitative evaluation indicates that the detachment capability of these three surfactants follows C12TAB > C14TAB ≈ C16TAB≈C8TAB > C10TAB > C18TAB. Our results indicated that the chain length of surfactant play important role in tertiary oil recovery, and a compatibility should be considered.

Influence of Chain Length of Gradient and Block Copoly(2-oxazoline)s on Self-Assembly and Drug Encapsulation.

Amphiphilic gradient copolymers represent a promising alternative to extensively used block copolymers due to their facile one-step synthesis by statistical copolymerization of monomers of different reactivity. Herein, an in-depth analysis is provided of micelles based on amphiphilic gradient poly(2-oxazoline)s with different chain lengths to evaluate their potential for micellar drug delivery systems and compare them to the analogous diblock copolymer micelles. Size, morphology, and stability of self-assembled nanoparticles, loading of hydrophobic drug curcumin, as well as cytotoxicities of the prepared nanoformulations are examined using copoly(2-oxazoline)s with varying chain lengths and comonomer ratios. In addition to several interesting differences between the two copolymer architecture classes, such as more compact self-assembled structures with faster exchange dynamics for the gradient copolymers, it is concluded that gradient copolymers provide stable curcumin nanoformulations with comparable drug loadings to block copolymer systems and benefit from more straightforward copolymer synthesis. The study demonstrates the potential of amphiphilic gradient copolymers as a versatile platform for the synthesis of new polymer therapeutics.