Effect of alkyl chain length on the thermophysical properties of pyridinium carboxylates

In the present study,new series of pyridinium carboxylate protic ionic liquids (PILs) were synthesized by pairing pyridinium cation with carboxylate anion from C1-C3 forming pyridinium formate ([CsH6N+][HCOO-]),pyridinium acetate ([CsH6N+][CH3COO-]) and pyridinium propionate ([C5H6N+][CH3CH2COO-]) respectively.The physical properties namely,density,viscosity,surface tension (298.15-343.15) K,and refractive index (293.15-323.15) K were measured.Thermal properties namely,glass transition temperature,molar heat capacity,and thermal decomposition temperatures were also determined.The thermal expansivity was calculated using the experimental density data.The effect of increasing the alkyl chain length on the thermophysical properties of the pyridinium carboxylate PILs has been evaluated.As expected the physical properties i.e.density,viscosity,surface tension and refractive index of the investigated pyridinium carboxylates decreased with increasing temperature.In general pyridinium carboxylate PILs possessed low viscosity,high thermal stability and excellent hydrogen bonding capability,and these properties lead them to outperform conventional solvents employed for lignin dissolution.     

Effect of alkyl chain length grafted to graphene nanoplatelets on the characteristics of polypropylene nanocomposites

To improve the compatibility of graphene nanoplatelets (GNPs) to polypropylene (PP), alkyl chains were grafted to the GNPs’ surfaces by chemical reactions between alkyl amines and the corresponding functional groups of the GNPs. Hexylamine, dodecylamine, and octadecylamine were used respectively to prepare three different alkyl‐grafted GNPs (alkyl‐GNPs) with different alkyl chain lengths. Functional group analysis of the alkyl‐GNPs by Fourier transform infrared confirmed the alkyl‐grafting reaction. PP/alkyl‐GNP nanocomposites with 0.5 phr of hexyl‐, dodecyl‐, or octadecyl‐GNPs were prepared respectively by melt‐blending and compression molding and their mechanical and thermal properties and fracture surfaces morphology were investigated. With increasing alkyl chain length the flexural strength and melting temperature increased marginally but the flexural modulus, impact strength and storage modulus of the nanocomposites increased to a large extent. POLYM. ENG. SCI., 59:752–756, 2019. © 2018 Society of Plastics Engineers     

Effect of alkyl carbon chain length and ethylene oxide content on the performance of linear alcohol ethoxylates

A grid of 30 surfactants varying from C₈ to C₁₈ in carbon chain length and from 40 to 80% in ethylene oxide (EO) content were examined to determine the effect of molecular structure on the physical properties (density, melting point, solution viscosity) and performance properties (surface activity, detergency, hard-surface cleaning, foaming, wetting) of linear alcohol ethoxylates. Results show that while physical propeties are influenced primarily by EO content, both carbon chain length and EO content are important to performance. Optimum carbon chain length is also shown to depend strongly on surfactant concentration. Presented at the AOCS meeting in New Orleans in May 1987.     

Effect of alkyl carbon chain length and ethylene oxide content on the performance of linear alcohol ether sulfates

A series of linear alcohol ether sulfates varying in alkyl carbon chain length and ethylene oxide content was evaluated with respect to surface activity, viscosity, foaming, and detergency. Performance data agree well with surface property data. A low level of EO is best in terms of effectiveness and efficiency in lowering surface tension, which is why a low-mole ether sulfate salt-thickens better, produces foam which is more tolerant of soil, and gives good detergency performance. A lauryl-range alkyl carbon chain length is best for foaming and salt-thickening, but a higher carbon chain length appears to be better for detergency performance.     

烷基碳链对N-烷基二甲基甜菜碱性能的影响

甜菜碱表面活性剂的烷基碳链的长度对其表面活性及其它性质有不同程度的影响。通过实验测定碳链长度对泡沫力、洗涤力等的影响情况,为不同使用目的选择合适长度碳链的烷基甜菜碱提供依据。结果表明:十四烷基甜菜碱的起泡力较强,十二烷基的次之;十四、十六烷基甜菜碱的洗涤力较强,十四烷基的洗涤力更强;相对碳链长的甜菜碱活性剂具有较好的加溶作用和钙皂分散力。     

烷基链长对咪唑类离子液体-甲醇体系局部组成的影响

在全浓度范围内测定了3种离子液体-甲醇体系,即1-乙基-3-甲基咪唑四氟硼酸盐-甲醇体系、1-丁基- 3-甲基咪唑四氟硼酸盐-甲醇体系和1-己基-3-甲基咪唑四氟硼酸盐-甲醇体系的核磁共振氢谱（1H NMR）,运用局部组成模型对离子液体和甲醇的化学位移进行关联,得到了表征溶液内部微观环境的局部摩尔分数,分析了烷基链长对咪唑类离子液体-甲醇体系局部组成的影响。结果表明在这3种离子液体-甲醇体系中,离子液体的局部组成与宏观组成差异性非常小,甲醇分子在侧链越长的咪唑类离子液体中越倾向于自身缔合。     

Surface hydrophobicity: effect of alkyl chain length and network homogeneity

Understanding the nature of hydrophobicity has fundamental importance in environmental applications.Using spherical silica nanoparticles(diameter=369±7 nm)as the model material,the current study investigates the relationship between the alkyl chain network and hydrophobicity.Two alkyl silanes with different chain length(triethoxymethylsilane(C1)vs.trimethoxy(octyl)silane(C8))were utilised separately for the functionalisation of the nanoparticles.Water contact angle and inverse gas chromatography results show that the alkyl chain length is essential for controlling hydrophobicity,as the octyl-functionalised nanoparticles were highly hydrophobic(water contact angle=150.6°±6.6°),whereas the methyl-functionalised nanoparticles were hydrophilic(i.e.,water contact angle=0°,similar to the pristine nanoparticles).The homogeneity of the octyl-chain network also has a significant effect on hydrophobicity,as the water contact angle was reduced significantly from 148.4°±3.5°to 30.5°±1.0°with a methyl-/octyl-silane mixture(ratio=160:40μL·g^–1 nanoparticles).     

Phase behavior of fatty acid/oil/water systems: Effect of the alkyl length chain acid

The phase behavior of different fatty acids (FA) in pseudo-ternary mixtures [(water)/(FA) + (alcohol)/(oil)] was studied. The Winsor I-III-II transitions of ionized compounds were attained by varying the FA composition through the formulation scan. The middle-phase volume, the pH of the optimum system, and the partition coefficient increased with the chain length of FA. Conversely, the acid partition coefficient allows calculation of the Gibbs free energy of transfer of a CH₂ group from oil to water, which is found to be +0.87 J/mol.     

Influence of chain length on the rate of hydrolysis of polyoxymethylene ethers

Four series of polyoxymethylene ethers (polyformals) [RO(CH₂O)_nR] where R is isopropyl, ethyl, methyl, or methoxyethyl and n = 1–3 have been prepared, examined by GLC, separated by fractional distillation, and characterized by NMR. Rate constants for the aqueous acid hydrolysis of all the compounds have been determined. The isopropyl series appears to be a special case, and as reported in the literature (but in aqueous dioxane), all members of this series hydrolyze at the same rate. In the other series, there is a definite increase in rate, which never exceeds fourfold, in going from n = 1 to n = 2. This increase differs considerably from the 100-fold increase reported by others in going from CH₃OCH₂OCH₃ to CH₃O(CH₂O)₂CH₃. In all series, the n = 3 compound hydrolyses at practically the same rate as the n = 2 compound.     

Characterization of in situ prepared nanocomposites of PS and TIO2 nanoparticles surface modified with alkyl gallates: Effect of alkyl chain length

Incorporation of surface modified TiO₂ nanoparticles into polystyrene (PS) matrix was achieved by in situ bulk radical polymerization of styrene. The surface of TiO₂ nanoparticles was modified with four amphiphilic esters of the gallic acid (octyl, decyl, lauryl and cetyl gallate), which have different lengths of hydrophobic alkyl chain (C8–C16). FTIR and UV‐Vis spectroscopy measurements confirmed the formation of a charge transfer complex between surface Ti atoms and gallic esters. Microstructural characterization of the synthesized nanocomposites revealed that the best dispersion of TiO₂ nanoparticles in PS was achieved when the TiO₂ surface was modified with octyl gallate. The presence of surface modified TiO₂ nanoparticles by different alkyl gallates does not have an influence on the molecular weight and glass transition temperature of PS matrix. On the other hand, thermal and thermo‐oxidative stability of PS were significantly improved by incorporation of surface modified TiO₂ nanoparticles. The most pronounced improvement of thermal and thermo‐oxidative stability was observed for TiO₂ nanoparticles surface modified with octyl gallate. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Effect of alkyl chain length on the electrochemical perfluorination of n-alkane (C6–C10) carboxylic acid chlorides

Electrochemical perfluorination (ECPF) of n-hexanoyl, n-heptanoyl, n-octanoyl, n-nonanoyl and n-decanoyl chlorides was carried out under identical experimental conditions in liquid HF. The product distribution among perfluorinated carboxylic acids, perfluoro ethers, perfluoroalkanes, isomerised and fragmented products containing less number of carbon atoms was identified using ¹⁹F NMR. The selectivity of C₆–C₁₀ perfluoro carboxylic acid varied between 29 and 36%. The alkali insoluble perfluoro cyclic ether and perfluoro alkane fractions increased with increasing chain length. The increase of perfluoroalkane fractions is mainly due to decarboxylation. Cyclic ether fractions also decreased slightly with increase in chain length. Among the cyclic ethers α substituted oxolanes were the predominant products. Six membered cyclic ethers were always found to contain β substitution. The possible pathways for these products are also indicated. An erratum to this article can be found at     

Effect of alkyl group on the chain extension of phosphites in polylactide

Polylactide (PLA), which is synthesized from natural resources and can degrade easier, possesses high mechanical strength, so it is a reasonable substitute for petroleum‐based plastics. Phosphites can increase the stability of PLA through chain extension with the hydroxyl and carboxyl groups simultaneously. But there are few reports on the structural effects of phosphites on the chain extension of PLA. In this article, three kinds of phosphites with different amounts of aryl and alkyl groups were used as chain extenders in PLA and were compared in detail. The molecular weights, complex viscosities, and storage moduli of virgin PLA and PLA stabilized by three different phosphites were characterized by gel permeation chromatography and rheometry. The results show that the presence of alkyl groups is not beneficial for chain extension, as the more alkyl groups there are, the worse the chain extension is. Regarding the three phosphite chain extenders added to PLA—triphenylphosphite (TPP), diphenylisooctylphosphite (PTC), and phenyldiisooctylphosphite (PDOP)—the number of alkyl groups in them can be ranked as follows: PDOP > PTC > TPP. Since PDOP had the most alkyl groups, the chain extension of PDOP was the weakest. In addition, the product, which was formed due to the chain extension of PLA and TPP, had some plastication, thus enabling PLA to move more freely and making it easier to process. J. VINYL ADDIT. TECHNOL., 25:144–148, 2019. © 2018 Society of Plastics Engineers     

Effect of chain length of the alkyl in quaternary ammonium substituents on the adhesion-to-fiber,aerobic biodegradation,and desizability of quaternized cornstarch

Commercial native cornstarch was subjected first to acid hydrolysis using HCl and then to cationization using N-(3-chloro-2-hydroxypropyl) trialkylammonium chloride (CHPTAA) to introduce quaternary ammonium substituents onto starch chains with a series of degrees of substitution (DS). Afterward, the effect of chain length of the alkyl in cationic substituents on the quaternization, aqueous paste viscosity, adhesion-to-fiber, aerobic biodegradation, and desizability of starches was investigated for warp sizing. The number of carbon atoms of alkyl in CHPTAA was 1, 2, and 3, corresponding to the introduction of 3-(trimethylammonium chloride)-2-hydroxypropyl (TMACHP), 3-(triethylammonium chloride)-2-hydroxypropyl (TEACHP), and 3-(tripropylammonium chloride)-2-hydroxypropyl (TPACHP) substituents onto starch chains, respectively. The level of starch quaternization was examined in the range of 0–0.06 in DS value. Experimental results demonstrated that the chain length displayed significant effects on the quaternization, paste viscosity, adhesion-to-fiber, aerobic biodegradation, and desizability. Increase in the number of carbon atoms of alkyl resulted in decreased reaction efficiency, reduced adhesion, somewhat slower biodegradation, and declined desizability. In addition to the chain length, the level of starch quaternization also showed marked effects on the viscosity, adhesion-to-fiber, aerobic biodegradation, and desizability. Based on the reaction efficiency, adhesion-to-fiber, aerobic biodegradation, and desizability, TMACHP cornstarch was superior to the TEACHP and TPACHP ones.     

Reduction of blood and liver cholesterol in the rat by straight and branched chain alkyl amines

The activities of a branched chain and several straight chain amines (C₁₂ to C₁₈ chain length), and the azasteroid 25-aza-5α-cholestane were compared with those of 20,25-diazacholesterol dihydrochloride, which is a potent hypocholesterolemic agent in the rat. These amines and azasteroids inhibit the Δ²⁴-sterol reductase system in the tobacco hornworm,Manduca sexta (L.), and also block the conversion of C₂₈ and C₂₉ plant sterols to cholesterol, with a resulting accumulation of desmosterol. The effects of these compounds in the rat were determined on body weight gain, cholesterol, desmosterol, and lipid composition of blood, feces, liver, and epididymal fat pad weight. The two azasteroids and the branched chain amine, N,N-dimethyl-3, 7,11-trimethyldodecanamine, had the greatest effect, reducing total plasma lipids and plasma sterols to approximately 40–50% of the levels in control rats and produced a concomitant increase in plasma and liver desmosterol. The branched chain dodecanamine caused a reduction in both feed consumption and body weight gain. The branched and straight chain dodecanamines also severely reduced epididymal fat pad weight. Our results demonstrate that the simple azasteroid, 25-aza-5α-cholestane, is a more potent inhibitor of cholesterol biosynthesis than the diazasterol and that the Δ²⁴-sterol reductase system in a mammal can be inhibited by simple, nonsteroidal, acyclic amines.     

Wettability modification of lignite by adsorption of alkyltrimethylammonium bromides with different alkyl chain length

To overcome the problem of moisture re-adsorption of dried lignite with common evaporation drying methods, a set of linear alkyl quaternary ammonium surfactants (C₁₀TAB, C₁₂TAB, and C₁₆TAB) were used to modify lignite surface, and the effects of alkyl chain length on the adsorption characteristics of surfactants and wettability of lignite surface were evaluated. Pseudo-first and pseudo-second-order kinetic models and Langmuir model were, respectively, used to simulate adsorption kinetics and adsorption isotherms. The results showed that three surfactants gradually formed double-layer adsorption on lignite surface and the loading of surfactant increased with the length of alkyl chain. X-ray photoelectron spectroscopy analysis showed that C₃H₉N⁺ moiety of the surfactants would preferentially interact with O?C?O groups of lignite. Results of wetting heating and moisture re-adsorption showed that three surfactants obviously decreased hydrophilicity and restrained moisture re-adsorption of lignite, but with the formation of double-layer adsorption, hydrophilic headgroups of surfactant faced outward, which caused increase in hydrophilicity of lignite. As a result of two opposite effects of surfactant chain length on lignite wettability, the effect of C₁₂TAB on decreasing hydrophilicity was the best among the three chosen surfactants.     

Cocrystallization mechanism of poly(3-alkyl thiophenes) with different alkyl chain length

The crystallization rates of poly(3-alkyl thiophene) (P3AT) cocrystals having different alkyl chain length (e.g. hexyl and octyl) of the components are measured using differential scanning calorimetry (DSC) technique. Two pairs of cocrystals with varying compositions of the components viz. poly(3-octyl thiophene) (P3OT(R), regioregularity 89 mol%) and poly(3-hexyl thiophene) [P3HT(R), regioregularity 92 mol% and P3HT-2 regioregularity 82 mol%] are used. In both the systems the isothermal temperature range (TR) in the same time scale of crystallization is found to decrease with increasing alkyl chain length in the blends. The crystallization rate at the same T_c decreases with increasing alkyl chain length P3AT concentration and the Avrami exponent values of cocrystals are same with those of the component values. The low Avrami exponent values (0.23-1.16) in all the samples suggest the presence of rigid amorphous portion which can not diffuse out quickly from the crystal growth front (soft impingement). Analysis of crystallization rate using Laurintzen-Hoffman (L-H) growth rate theory indicates that there is regime-I to regime-II transition in all the samples. The product of lateral (σ) and end surface energy (σ_e) values are found to decrease with increasing the concentration of longer alkyl chain P3AT in the blend. Analysis of σ values according to a theory of Hoffman et al. [Hoffman JD, Miller RL, Marand H, Rotiman DR. Macromolecules 1992;25:2221. [14]] indicates that there is chain extension of the components in the melt of the blends, however, the entropy of cocrystallization has different sign to the two systems. Cocrystallization in P3HT(R)/P3OT(R) system is an entropy driven process but that in P3HT(2)/P3OT(R) system is entropy forbidden process. A possible explanation of cocrystallization in the later system has been attributed from small interaction between the components.     

Mechanical reinforcement of polyethylene using n‐alkyl group‐functionalized multiwalled carbon nanotubes: Effect of alkyl group carbon chain length and density

Polyethylene (PE) is one of the most produced synthetic resins in the world. Functionalized multiwalled carbon nanotube (MWCNT) is a potential nanoscale filler to realize the next generation strong and multifunctional PE composites. We demonstrate that MWCNTs grafted with short n‐alkyl groups are effective nanofillers for mechanical reinforcement of PE composites. At 1 wt% filler loading, the yield stress and Young's modulus improve significantly up to 54 and 63% compared with neat PE, respectively. Among ductile properties, tensile strength increases up to 30%; ultimate strain is preserved; and toughness increases up to 33%. More important, we show that short n‐alkyl groups can be grafted on MWCNTs much easier than long chain polymers. Further, we find that alkyl groups of C14–C18 chains have the optimum length for reinforcement. The optimum density of grafted alkyl groups is around 0.390–0.423 μmol/mg when the C14 alkyl groups are used. Overall, the results manifest that MWCNTs grafted with n‐alkyl groups with suitable length and density are efficient nanoscale fillers for high‐performance PE composites. POLYM. ENG. SCI., 54:336–344, 2014. © 2013 Society of Plastics Engineers     

Influence of alkyl chain length on the gelation mechanism of thermoreversible gels of regioregular poly(3‐alkyl thiophenes) in xylene

The gelation rates of poly(3‐alkyl thiophenes) (P3AT) are strongly dependent on the pendent alkyl chain length. Poly(3‐hexyl thiophene (P3HT) gels at higher isothermal temperatures than that of poly(3‐dodecyl thiophene), (P3DDT). Gelation rate has been expressed as a combination of a temperature dependent function f(T) and a concentration dependent function (φⁿ); φ being the reduced overlapping concentration of P3AT. From the slope of double logarithmic plot of gelation rate and φ, n values are calculated to be 0.52 and 0.60 for P3HT and P3DDT, respectively. These values are close to the value of percolation exponent β (0.45) for three‐dimensional lattice; so both the gels may approximately obey three dimensional percolation model. The f(T) of gelation rate consists of two steps (i) coil‐to‐rod transformation followed by (ii) fibrillar crystallization. The coil‐to‐rod transition is accompanied by a red shift in the π–π* transition band in UV–vis spectra. Flory and Weaver theory is used to understand the coil‐to‐rod transformation process. The theory of fibrillar crystallization extended to dilute solution has been employed to understand the crystallization process. The results clearly indicate that the activation energy of conformational change (ΔF) is higher for P3DDT than that of P3HT. But the free energy change for the formation of critical size nucleus (Δ G) is lower for P3DDT than that of P3HT. A comparison of ΔF and Δ G values indicate conformational ordering is the rate‐determining step for P3AT with dodecyl substituent whereas crystallization is the rate‐determining step for P3AT with hexyl substituent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2528–2537, 2007     

芳基烷基磺酸盐链长对烷烃的油-水动态界面张力的影响

采用旋转滴法测定系列自制芳基烷基磺酸盐（C_nNPAS, n=8,10,12,14,16）水溶液对烷烃的油-水动态界面张力,考察了表面活性剂烷基链长、表面活性剂浓度、弱碱浓度、烷烃碳数等因素对油-水动态界面张力的影响。结果表明,增大C_nNPAS的烷基链长和碱含量均会使界面张力达到稳定值的时间增长;增加C_nNPAS浓度和烷烃碳数均会使界面张力动态变化加快,达到平衡所需时间减少。C_nNPAS表面活性剂可在低浓度范围较明显地降低界面张力,而随着浓度的增加界面张力回升明显。