Influence of hydrophobe type and extent of branching on environmental response factors of nonionic surfactants

A number of ethoxylated nonionic surfactants differing in hydrophobe branching and chainlengths have been evaluated for environmental responses. Screening biodegradation tests show that those nonionics having more than one methyl group per hydrophobe degrade considerably slower than those having less extensive branching. Continuous flow-through activated sludge tests, simulating actual waste treatment, show that the more highly branched nonionics biodegrade more slowly and less extensively than those with less hydrophobe branching. In addition, treated effluents originating from influents containing the more highly branched nonionics tend to be more surface active and more toxic to aquatic species than those originating from influents containing surfactants with less hydrophobe branching. Under conditions simulating plant stress, such as high surfactant concentrations in the influent or low temperature, biodegradation of the highly branched nonionics was considerably less extensive, while biodegradation of the linear nonionics was not affected to any measurable degree compared to more normal operating conditions. Presented at the 81st American Oil Chemists’ Society Annual Meeting, April 22–26, 1990, Baltimore, Maryland.     

Synthesis and surface activity of nonionic surfactants containing fluorocarbon hydrophobes

Nonionic surfactants having polydisperse polyoxyethylene chains and highly fluorinated hydrophobes were synthesized via a complex reaction route and their adsorption at water/air interfaces studied. They exhibit high surface activity and decrease both effectively and efficiently the surface tension of their aqueous solutions. The effect of the length of the polyoxyethylene chain upon surfactant surface activity is relatively low. Lower values of surface tension, below 30 mN m^?1, are obtained for surfactants having a low degree of ethoxylation. Surfactants having two terminal highly fluorinated hydrophobes are less surface active than analogues with one terminal hydrophobe.     

Structural characterization of FCC feeds from Indian refineries by NMR spectroscopy

Fluid catalytic cracking (FCC) feeds from four Indian refineries are structurally characterized by ¹H, gated-decoupled ¹³C, distortionless enhancement by polarization transfer (DEPT) and 2D ¹H–¹³C HETeronuclear CORrelation (HETCOR) and other 2D nuclear magnetic resonance (NMR) methods. Detailed structural analyses are completely supported by a range of NMR information including chemical shifts of ¹H and ¹³C, CH_n type distributions and ¹H –¹³C connectivities. The average structural parameters like branching sites, average number of branching per molecule, average length of side chains, percentage of saturates, aromatics and naphthenes are obtained from these NMR data. A novel approach based on “multipoint spline base line correction” is employed for estimation of naphthenes and n-paraffins that gives better quantitative estimation than the conventional methods. In this paper, importance is given to the study of those structural parameters that plays a key role in cracking chemistry as well as coke forming tendency of the feedstock. To the best of our knowledge, this is the first attempt to characterize and quantitatively estimate compositions of the high boiling fractions of petroleum feed by NMR methods and especially the complex structure of vacuum gas oil (VGO) fractions used in Indian refineries. The importance of this paper is to help in optimizing the product slate of Indian refineries through proper feedstock blending using few hundreds of million metric tons (MMT) of crude oil consisting of blends of light crudes with different heavy crudes and bottom of the barrel due to escalating cost of crudes.     

Triple-detector GPC characterization and processing behavior of long-chain-branched polyethylene prepared by solution polymerization with constrained geometry catalyst

Fourteen long-chain branched (LCB) polyethylene (PE) samples were prepared by a constrained geometry catalyst. The PE samples had average branching frequencies of 0.06-0.98 branches per polymer chain, as determined by the nuclear magnetic resonance spectroscopy (¹³C NMR). These samples, as well as five linear PEs were characterized using a gel permeation chromatography (GPC) coupled with online three-angle laser light scattering (LS), differential refractive index (DRI), and viscosity (CV) detectors. The root mean-square radius of gyration intrinsic viscosity ([η]), and molecular mass (M) of the PEs were measured for each elution fraction. Based on the comparison of the long-chain branching (LCB) PEs with their linear counterparts and the Zimm-Stockmayer equation, the distributions of long-chain branch frequency (LCBF) and density (LCBD) as function of molecular mass were estimated. It was found that although the LCBF increased with the increase of molecular mass, the LCBD showed a maximum value in the medium molecular mass range for most of the PE samples. The average LCBD data from the GPC analysis were in good agreement with the ¹³C NMR measurements. The rheological properties and processing behavior of these samples were also assessed. While the long chain branching showed significant effects on the modulus and viscosity, it did not improve the processing. Compared to linear PE, polymer melt flow instabilities such as sharkskin, stick-slip and gross melt fracture developed in extrusion of LCB PEs occurred at lower wall shear stresses and apparent shear rates.     

Synthesis and characterization of branched polymeric ionic liquids with imidazolium chloride segments

A branched polymeric ionic liquid (PIL) with imidazolium cation segments in the main chain connecting branching points was prepared in 95% yield by heating an equimolar mixture of 1,3,5-tris-(4-chlorobutoxy)-benzene and 1,3,5-tris-(4-imidazol-1-yl-butoxy)-benzene at 80 °C for 16 h. Similarly, condensation of a mixture of 1,3,5-tris-(4-imidazol-1-yl-butoxy)-benzene and 1,4-dichlorobutane in 1:1.5 molar ratio produced a second branched PIL in 94% yield. These branched PILs were characterized by FT-IR, ¹H, ¹³C NMR, TGA, and elemental analysis.     

Effects of aluminium content on the molecular structure and properties of polyaluminocarbosilane for SiC fibre fabrication

Polyaluminocarbosilane (PACS) is an important precursor for silicon carbide (SiC) fibres and ceramics. Much work has focused on the sintering effect of elemental Al, and it was found to increase density and inhibit grain growth during the pyrolysis of the SiC_xO_y phase at high temperatures. In addition to the sintering effect, Al may also affect the detailed molecular structure and the related properties of the precursor. In this work, PACS with different Al contents are prepared by a high-pressure method. The structural forms of the component elements are quantitatively determined by ¹H NMR, ²⁹Si NMR, DEPT, ²⁷Al MAS NMR and elemental analysis, and a method of determining the relative branching degree of PACS is proposed. It is found that increasing the Al content in the precursor leads to an increase in the weight percentage of the SiC₃O, CH₂ and CH groups, while the content of the SiC₄ groups remains almost unchanged, which consequently causes a rise in the relative branching degree of the molecular structure. The rheological properties of the precursors are investigated on a monofilament spinning device. It is found that the apparent viscosity rises, and the spinnability of the precursor weakens, with increasing Al content, while the non-Newtonian index becomes larger, indicating a decrease in the pseudo-plasticity of the precursor. In addition, the ceramic yield becomes higher, which is definitely correlated to the more branched and ring molecular structures.     

Viscosity characteristics of aqueous solutions of block copolymers of propylene and ethylene oxides

Brookfield viscosity measurements were made on aqueous solutions of surface-active agents composed of block copolymers of propylene and ethylene oxides in which the molecular weights of the polymers varied from 1100 to over 15,000. The hydrophobia bases were polyoxypropylene glycols varying in molecular weight from 940 to 4000. To these were added varying amounts of ethylene oxide so that the polyoxyethylene hydrophil comprised from 15 to 80% of the surfactant total weight. This work has materially expanded previous viscosity studies of aqueous solutions of nonionic surfactants by using a unique type of hydrophobe, two ethylene oxide chains, and far higher molecular weights of hydrophobe and of hydrophil, up to 280 moles of ethylene oxide. The surface-active agents with hydrophobe base molecular weights from 940 to 1100, and in which the polyoxyethylene sections comprised from 15 to 80% of the total weight, did not form gels in aqueous solution. Some surfactants with a hydrophobe base molecular weight of 1750 to 2750, to which varying amounts of polyoxyethylene were added, formed gels in water at a surfactant concentration range of 40% to 80%. With a hydrophobe molecular weight of 3250, gels formed at from 30% to 90% surfactant concentration, while with one nonionic derived from a 4000 molecular weight hydrophobe, a gel formed at only 20% polyol concentration. Two viscosity maxima were found in some cases, as reported occasionally for other systems. An increase in temperature from 0C to 50C generally reduced the viscosity of systems based on hydrophobes of 1175 and lower molecular weights, and increased it in systems based on hydrophobes of 1750 and higher molecular weights. The behavior of these surfactants in forminggels is explained on the basis of hydrogen bonding, micellar aggregation and water entrapment. The moles of water per ethylene oxide group in the adduct varied with the hydrophobe base weight and with the polyoxyethylene hydrophil, and within systems showing maximum viscosities, ranged from 0.3 to 17.1, at 25C, which is much higher than observed in other nonionics.     

Synthesis of new versatile functionalized polyesters for biomedical applications

A new family of branched polymers was synthesized for different biomedical applications such as the preparation of targeted nanoparticulate drug carriers. They are new copolymers of hydroxy-acids and allyl glycidyl ether. The functional groups (allyl-, hydroxyl- and carboxyl-) to which various groups will be grafted are linked to the polymer backbone. The resulting polymers were characterized by ¹H NMR, ¹³C NMR, size exclusion chromatography (SEC), elemental analysis and differential scanning calorimetry (DSC). In vitro cytotoxicity assays were also conducted to ensure biocompatibility of the polymers. In order to obtain some structural evidences, different molecules have been grafted on the pendant groups. The method allows a rapid and easy synthesis of allyl-, hydroxyl- and carboxyl-branched degradable polymers for grafting various bioactive molecules.     

Characterization of the micellar structure of a barium nonylphenolate/Barium carbonate complex by nuclear magnetic resonance spectroscopy

The micellar structure of a barium nonylphenolate/barium carbonate complex was characterized by ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy. Several NMR techniques, including measurement of spin-lattice relaxation time, chemical shift variation, and line width of the ¹H NMR signal and solid-state ¹³C NMR data, were used in this study. NMR results indicate that the prepared barium nonylphenolate and barium carbonate complex formed a micelle structure with the oxygen atom of the nonylphenolate ring oriented toward the solid-state center core of barium carbonate while the highly branched aliphatic chain pointed outward to the hydrocarbon solvent.     

Hyperbranched polymers containing oxazoline monomers and succinic anhydride: Applications in fast drying,low solvent coating formulations

Melt-polycondensation of succinic acid anhydride with oxazoline-based diol monomers gave hyperbranched polymers with carboxylicacids terminal groups. ¹H NMR and quantitative ¹³C NMR spectroscopy coupled with DEPT-135 ¹³C NMR experiment showed high degrees of branching (over 60%). Esterification of the acid end groups by addition of citronellol at 160 °C produced novel white spirit soluble resins which were characterized by Fourier transform-infrared (FTIR) spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Blends of the new hyperbranched materials with commercial alkyd resins resulted in a dramatic, concentration dependent drop in viscosity. Solvent-borne coatings were formulated containing the hyperbranched polymers. Dynamic mechanical analysis studies revealed that the air drying rates of the new coating systems were enhanced compared with identical formulations containing only commercial alkyd resins.     

Aliphatic tertiary amine mediated synthesis of highly branched polylactide copolymers

In the Sn(Oct)₂ catalyzed bulk copolymerization of l-lactide (LLA) and a large amount of branching comonomer 2,2-bis(hydroxymethyl)butyric acid (BHB) (LLA/BHB/Sn(Oct)₂ ratio is 5:1:0.05, 135 °C), low molecular weight of copolymers with inhomogeneous structure were generated. MALDI-TOF mass spectrum demonstrated that the lower molar mass fraction was dominated with the BHB homo-polycondensation products; whereas the higher molar mass fraction was mainly composed of linear chains of poly(l-lactide) (PLLA) bearing one BHB unit. The addition of aliphatic tertiary amine to this polymerization system could effectively enhance the molecular weight of the obtained copolymers, whereas, aromatic tertiary amines and aliphatic primary and secondary ones were not so effective. The obtained PLLA copolymers were characterized by GPC, ¹H NMR, ¹³C NMR and MALDI-TOF MS, which verified that they were composed of LLA and BHB units and had the highly branched structure. The degree of branching was about 0.23–0.30. Thermal analyses by TGA and DSC demonstrated that the resulting highly branched PLLA copolymers were amorphous. Compared with linear PLLA, the highly branched PLLA copolymers were thermally more stable and had lower T_g. The mechanism of aliphatic tertiary amine mediated synthesis of medium molecular weight of highly branched PLLA copolymers was proposed.     

Waste Cooking Oil-Based Novel Gemini Imidazolinium Surfactants With Carbonate Linkage: Green Synthesis,Characterization and Properties Evaluation

Imidazolinium surfactants belong to the category of cationic surfactants that have already gained the great interest of researchers due to their varied range of commercial applications. With the advancement in the field of surfactants research, imidazolinium surfactants are being converted into their corresponding gemini surfactants. Gemini surfactants are known to have exceptional self‐assembling characteristics and exclusive interfacial activity that include much lower CMC and better ability to reduce surface tension than their conventional monomeric counterparts. Long reaction time associated with conventional thermal synthetic procedures and high production costs are the two major issues involved in the synthesis of gemini surfactants. The present research work involves the microwave synthesis of novel gemini imidazolinium surfactants with carbonate linkage. In order to synthesize cost effective gemini surfactants, waste cooking oils have been used as raw materials. Structural characterization of synthesized gemini surfactants has been achieved through ¹H‐NMR, ¹³C‐NMR and FT‐IR.     

Multivariate quantitative structure-activity relationships for the aquatic toxicity of technical nonionic surfactants

The aquatic toxicity of 36 technical nonionic surfactants (ethoxylated fatty alcohols) was examined toward two freshwater animal species, the fairy shrimp Thamnocephalus playtyurus and the rotifer Brachionus calyciflorus. Responses of the two species to the surfactants were generally similar. A multivariate-quantitative structure-activity relationship (M-QSAR) model was developed from the data. The M-QSAR model consisted of a partial least squares model with three components and explained 92.4% of the response variance and had a predictive capability of 89.1%. The most important physicochemical variables for the M-QSAR model were the number of carbon atoms in the longest chain of the surfactant hydrophobe (redC), the molecular hydrophobicity (log P), the number of carbon atoms in the hydrophobe (C), the hydrophilic-lipophilic balance according to Davis (Davis), the critical packing parameter with respect to whether the hydrophobe was branched or not (redCPP), and the critical micelle concentration. Surfactant toxicity tended to increase with increasing alkyl chain lengths.     

NMR analysis of butyl acrylate/methylmethacrylate/α‐methyl styrene terpolymers

Composition analysis for butyl acrylate (BA)/ methyl methacrylate (MMA)/α‐methyl styrene terpolymers was carried out by NMR spectroscopy methods. ¹H‐NMR was used primarily for this analysis, but because the method did not provide independent measurements for the BA and MMA fractions, the terpolymer composition analysis was open to higher than normal levels of uncertainty. Supplementary analyses were made with quantitative ¹³C‐NMR methods to confirm the results from ¹H‐NMR (quantitative ¹³C‐NMR was used to provide corroboration of selected composition analyses). To confirm spectral assignments in the ¹H‐ and ¹³C‐NMR spectra, heteronuclear multiple quantum coherence and J Modulated Spin Echo (JMOD) pulse sequences were used. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2093–2098, 2007     

Aufklärung der Molekülstruktur von Rohölinhaltstoffen durch NMR-Spektroskopie. I. Struktur der Isoparaffine des Rohöls

Elucidation of the Molecular Structure of Petroleum Constituents by NMR Spectroscopy. I. Structure of Branched Paraffins in Petroleum Crude A correlation between the ¹³C resonance peaks and possible structural elements of branched paraffins of petroleum fractions is given. New information concerning the structure of branched paraffins of petroleum crude is provided.     

One-pot synthesis of comb-like copolymer bearing side chains composed of branched and linear polylactides

Ethyl cellulose (EC), lactide (LA) and branching comonomer 2,2-bis(hydroxymethyl) butyric acid (BHB) were copolymerized in xylene using Sn(Oct)₂ as catalyst. Catalyst amount and polymerization temperature were optimized for the effective introduction of certain amount of branched polylactide (PLA) into the side chains of comb-like copolymers having EC backbone. The characterization of the obtained copolymers by GPC and ¹H NMR demonstrated that the influence of polymerization temperature in the range of 110–150 °C on the efficient incorporation of branching units was not pronounced, whereas high amount of catalyst was the key point. The content of branching units in the copolymers could be enhanced by increasing the feed amount of BHB monomer. A plausible mechanism for the polymerization was proposed according to the model experiments. Compared with the comb-like copolymers with merely linear PLA side chains, the ones bearing both branched and linear PLA side chains had the following characters: (1) better solubility in the polar solvent of ethanol; (2) much faster hydrolysis degradation. These characters became more pronounced when the content of branching units in the side chains increased.     

Synthesis, Surface Active Properties of Novel Gemini Surfactants with Amide Groups and Rigid Spacers

A series of novel cationic gemini surfactants, bis-(N-(3-alkylamido-propyl)-N,N-dimethyl)-p-phenylenediammonium dichloride, were synthesized. The structures of the gemini surfactants were characterized by IR, ¹H NMR and ¹³C NMR. The Krafft temperatures of surfactants were determined through conductivity, the surface active properties in aqueous solution were studied at various temperatures by surface tension and conductivity. The thermodynamic functions of micellization process of the surfactants were also calculated by conductivity. The Krafft temperatures of the surfactants were 12, 13 and 28 °C. The values of CMC and Γ _max decreased with increasing the length of hydrophobic chains, but the values of CMC and α increased with increasing temperature. The process of micellization is a spontaneous, exothermic and entropy-driven process.     

Surfactants containing ethylene oxide: Relationship of structure to biodegradability

Anionic ethoxy sulfate and nonionic ethoxylate surfactants were prepared from the following straight-chain hydrophobes: fatty or Ziegler primary alcohols, oxo alcohols derived from straight-chain olefins, secondary straight-chain alcohols and straight-chain alkylphenols. These were studied to relate biodegrability to the following elements of structure: the nature of the connecting link, its position of attachment to the hydrophobe, the chain length of the hydrophobe, and the length of the ethylene oxide chain used. Previously described methods were used to estimate both rate and completeness of degradation in river water as well as activated sludge environments. Data are presented to support the following conclusions.

1. 1)
   All surfactants derived from straight-chain primary and secondary alcohols are rapidly and completely degraded with loss of surfactant properties. The length of the ethylene oxide chain from zero up to ten units has no effect on the rate or the completeness of degradation. In such surfactants, the ethylene oxide chain is completely degraded.     
   
   

New sulfur-containing polymers

Summary From ¹H NMR, ¹³C NMR and ¹³C — {¹H} off resonance experiments it was shown, that the main structural units are formed by an Anti-Markovnikov addition of the SH group to the C,C double bond.part 3, reference 3We wish to thank the Max-Buchner-Forschungsstiftung for a scholarship (program: 1145)     

Nonionic surfactant polarity index determination by inverse gas chromatography

Polyglycol nonionic surfactants are widely used in industrial and consumer products. Two classes of these surfactants, made from selected combinations of 1,2-butylene oxide, propylene oxide and ethylene oxide, were compared to alcohol ethoxylate (AE) and nonyl phenol ethoxylate nonionic surfactants in this study. Polyglycol copolymers consisted of either a polypropylene glycol (PPG) or polybutylene glycol (PBG) central hydrophobe. Ethoxylation of the hydrophobes produced polyethylene glycol hydrophilic blocks. Differences in hydrophobe polarity were determined by inverse gas chromatography (IGC). IGC is a useful analytical method by which the physical and chemical characteristics of a material are studied. The stationary surfactant material under study was coated onto an inert support and used as the packing for the column. A probe mixture, containing simple organic molecules of varying polarity, was injected, and the retention characteristics were measured. The retention characteristics of the standard probe mixture were used to reveal relative polarity information about the stationary surfactant coatings. Polarities of the four hydrophobes were (in decreasing order): PPG, PBG, nonyl phenyl and fatty alkyl. Comparisons were then made between the calculated hydrophile-lipophile balance values and polarity indices of the hydrophobes and their ethoxylates. The effects of hydroxyl groups on polarity were also studied and quantified.