Kulbir Singh

• PhD Chemistry
• St. Francis Xavier University

Critical micelle concentration (cmc) values have been determined for the mixed zwitterionic/cationic gemini systems of N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (ZW3-12)/N,N’bis(dimethyldodecyl)-,-alkanediammonium dibromide (12-s-12) systems. The cmcs for the mixed systems were determined through conductivity measurements. The degree of...

The micellar and morphological properties of symmetric, cationic gemini surfactants have been well studied in the literature as a function of nature and type of the spacer group and the length and type of hydrophobic chain. In this paper, we have examined the effects of tail asymmetry on the properties of a series of cationic surfactants, the N-alk...

Microstructural evolution of a cationic gemini surfactant butanediyl-1,4-bis(dodecyldimethylammonium bromide) (hereafter referred to as 12-4-12) micelles in the presence of two bile salts viz. sodium deoxycholate (NaDC) and sodium cholate (NaC) was investigated using surface tension, viscosity, nuclear magnetic resonance (NMR), and small angle neut...

The effect of bile salts viz. sodium cholate (NaC) and sodium deoxycholate (NaDC) on the size and transition of cetyltrimethylammonium tosylate(CTAT) micelles is examined by viscosity, cryogenic transmission electron microscopy (Cryo-TEM), small angle neutron scattering (SANS), nuclear Overhauser enhancement spectroscopy (NOESY) and ¹H NMR. The vis...

The cationic surfactant cetyltrimethylammonium tosylate (CTAT) forms highly viscous/viscoelastic solutions and worm-like micelles at relatively low concentrations. Effect of 1-alkanols with short to long alkyl chain viz. ethanol, 1-butanol, 1-hexanol and 1-octanol on CTAT micelles was examined. In particular, a detailed study on the effect of 1-hex...

The surface and self-assembly properties of a family of multiheaded, multitailed surfactants based on a tripentaerythritol backbone are described. Critical aggregation concentrations of these unusual surfactant systems have been determined from surface tension measurements; aggregate sizes in the presence and absence of a small amount of added elec...

In this paper, we report induced micellar growth and rheology modification for mixtures of anionic (Sodium dodecylsulfate, SDS) and zwitterionic (N-alkylated Glycine Derivative, Empigen BB or EBB) surfactants. Two non-aromatic hydrotropic salts (Hexyltrimethylammonium Bromide, C6TAB and/or dibutylenebis-(dimethylbutylammonium bromide), 4-4-4) are u...

The effect of ethylene glycol (EG), diethylene glycol (DEG) and their monoalkyl (C 1-C 6) ethers (cellosolves and carbitols) and dimethyl ethers (glymes and diglymes) on the micellar behavior of a cationic surfactant tetra-decyltrimethylammonium bromide (TTAB) in aqueous solution was examined from electrical conductivity measurements. The effect of...

The aqueous solution behavior of a poly(ethylene oxide)–poly(propylene oxide), PEO–PPO, star block copolymer Tetronic® T904 with solubilized phenol and benzene was examined by cloud point (CP), viscosity measurements, 1D and 2D NMR experiments, dynamic light scattering(DLS), and small angle neutron scattering (SANS) techniques. Both the solubilizat...

The effect of p-toluidine (PTD) on the growth of cationic surfactant micelles in aqueous solutions was examined by viscosity, UV-visible spectroscopy, dynamic light scattering (DLS), (1)H NMR and nuclear Overhauser effect spectroscopy (NOESY). Viscosity and scattering results are used to follow the growth of the aggregates and examine the structura...

The effect of 1-alcohols on aqueous solution behavior of polyethylene oxide–polypropylene oxide–polyethylene oxide (PEO–PPO–PEO) triblock copolymers was investigated from cloud point (CP), viscosity, dynamic light scattering (DLS) and 1H NMR. Three triblock copolymers Pluronics® P103, P104 and P105, each having same size middle PPO block but varyin...

The solubilization of four phenolic antioxidants, namely p-hydroxybenzoic acid (PHBAA), syringic acid, sinapic acid, and quercetin in micelles of an ethylene oxide (EO)-propylene oxide (PO) triblock copolymer Pluronic® P104 (EO27-PO61-EO27, PPO mol wt=3540, % PEO=40) was examined at different temperatures, pHs, and in the presence of sodium chlorid...

Interaction of 1-butanol (BuOH) with a cationic surfactant, cetyltrimethylammonium bromide (CTAB) aggregate, in water and salt solution has been studied by viscometry, small-angle neutron scattering (SANS), and 2D-NMR techniques. The experimental results are interpreted in terms of a possible micellar growth occurring in the presence of added alcoh...

The solution behavior of a typical cationic surfactant, tetradecyltrimethylammonium bromide, in mixed solvent systems composed of water and varying concentrations of α,ω-alkanediols; 1,2-ethanediol (ED), 1,4-butanediol (BD), 1,6-hexanediol (HD) and 1,8-octanediol (OD) was examined via electrical conductance measurements, 13C-NMR spectroscopy and sm...

Surfactant–alcohol systems are not uncommon in colloidal chemistry, what is rare is a specific emphasis on the environmental sensitive behaviour of 1-butanol (C4OH) in different surfactant solutions. Intermediate solubility of C4OH (in between totally soluble short chain alcohol and partially miscible long chain alcohol) has prompted us to study it...

The micellar and phase behavior of an ethylene oxide-propylene oxide branched octablock copolymer Tetronic T 904 (hereafter written as T904) in water and NaCl solutions was examined. The copolymer shows a cloud point (CP) ranging from 74-65°C in the concentration range of 1-10% and forms aggregates (micelles) with a hydrodynamic diameter around 10-...

The solubilization of benzene and toluene in micellar solutions and the effects on the micellization and micelle size of ethylene oxide-propylene oxide triblock copolymers were investigated by dynamic light scattering (DLS), small angle neutron scattering (SANS), and 2D NMR spectroscopy. The copolymeric surfactants have the same size as the middle...

Tetronics® (Poloxamines) are the least studied block copolymers with an X-shaped molecular geometry formed by four poly (propylene oxide, PPO) and poly (ethylene oxide, PEO) block chains, bonded to a central ethylenediamine group. Compared to their linear counterparts, the Pluronics, Tetronics® are novel, in that they possess superior physicochemic...

Isothermal titration calorimetry (ITC) and batch calorimetry techniques have been used to evaluate the effect of added antioxidant (Quercetin, QN) on the binding between a polymer/surfactant complex, namely the sodium salt of polystyrene sulfonate (PSS) and typical anionic surfactant sodium dodecylsulfate (SDS). An indirect isotherm approximation m...

Calorimetric and spectroscopic studies have been carried out to investigate the thermodynamics of temperature-induced micellization of Tetronic® T904 [(EO15PO17)2NCH2CH2N (PO17EO15)2] in aqueous salt solutions. High-sensitivity differential scanning calorimetry (HSDSC), nuclear magnetic resonance (NMR) and Fourier transfer infrared (FTIR) measureme...

The conformation and orientation of a series of zwitterionic surfactants (the alkyl-N,N-dimethylammoniopropanesulfonates, or Zwittergent® Detergents) has been studied via 13C chemical shift measurements and 2D NOESY spectroscopy. Chemical shift changes (Δδ values) support the tendency for the intercharge arm to adopt a ring-like orientation as the...

Micro- and nano-crystals of PbS with different morphologies have been successfully prepared at 80 °C under aqueous phase conditions by using cationic Gemini/dimeric (m-s-m) surfactants as capping agents. The effect of Gemini spacer length and concentration has been evaluated to make PbS crystal synthesis more selective. Well-defined PbS nano- and m...

A simple and effective method for the formation of stable multilamellar vesicles is reported as a potential application of ionic liquid materials (IL's) and as replacements for conventional surfactants used in such applications. The methodology is based on the various approaches for the formation of vesicles from oppositely charged surfactants. Pho...

Mixed micelle formation of binary cationic gemini (12-s-12, s=4, 6) and zwitterionic (N-dodecyl-N,N-dimethylglycine, EBB) surfactants has been investigated by measuring the surface tension of aqueous solution as a function of total concentration at various pH values from acidic to basic, under conditions of 298.15 K and atmospheric pressure. The re...

The pyrene fluorescence measurements have been carried out for various binary mixtures of micelle forming (L-alpha-diheptanoylphosphatidycholine, DHPC) and vesicle forming (L-alpha-dimyristoylphosphatidycholine, DMPC) phospholipids with different twin tail alkylammonium surfactants. The mixed micelle formation in all binary mixtures has been evalua...

The mixed micelle study of C10E8, C12E4, and C14E8 nonionic surfactants with 12-0-8, 12-0-10, 12-0-12, and 12-0-16 twin tail alkylammonium bromides has been carried out with the help of pyrene fluorescence, dynamic light scatterings (DLS), and electron spin resonance (ESR) measurements. The pyrene fluorescence allowed us to determine the mixed cmc...

Pyrene fluorescence and Krafft temperature measurements have been carried out for various combinations of cationic gemini (m-2-m) with zwitterionic surfactants by changing the length of the hydrophobic tail over the whole mixing range. The results have been evaluated by using the regular solution theory. All the mixtures of cationic gemini+zwitteri...

The mixed micellar properties of a triblock copolymer, Pluronic L64, (EO)13(PO)30(EO)13, and a nonionic surfactant, Triton X-100, in aqueous solution with conventional alkyl ammonium bromides and their dimeric homologues were investigated with the help of fluorescence and cloud point measurements. The composition of mixed micelles and the interacti...

The pyrere fluorescence measurements have been performed for the mixtures of diheptanoylphosphatidycholine (DHPC) with dimeric cationic, phosphonium cationic, and zwitterionic surfactants of C10 to C16 hydrocarbon tail length over the whole mixing range. From the I1/I3 versus total surfactant concentration plots, the mixed critical micelle concentr...

Mixed micelle formation by cationic 12-2-12 gemini with conventional single chain surfactants were studied with the help of conductivity, turbidity, and NMR measurements. The influence of steric contributions in the head group region and counterion effects on the mixed micelle formation have been explored. Favorable interactions are responsible for...

Mixed micelle formation by tetradecyltrimethylammonium (TTAB) and tetradecyltriphenylphosphonium bromides (TTPB) with benzyldimethyltetradecylammonium chloride (BTDACl) was studied with the help of conductivity and Kraft point measurements. The BTDACl + TTAB mixtures showed synergistic interactions whereas those of BTDACl + TTPB indicated weak anta...

The conductivity (κ) and Kraft temperature (KT) measurements were carried out for the binary combinations of dimeric cationic gemini, di(dodecyldimethylammonium bromide) (12-2-12), with alkyl phosphonium and ammonium bromide surfactants to evaluate the mixed micelle formation influenced by head group (i.e. dimeric and monomeric) and hydrophobic tai...

The mixed micelle formation by benzyldimethylhexadecylammonium chloride (BHDACl) with hexadecyltrimethylammonium bromide (HTAB), hexadecylpyridinium bromide (HPyBr), and hexadecylpyridinium choride (HPyCl) has been studied with the help of 1H and 13C NMR studies influenced by both the head-group modifications as well as mutual hydrophobicity. The r...