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Solid supported catalysts such as amines are in high demand for the chemical fixation of CO2 into commodity chemicals.

Double hydrophilic ABA-type amphiphilic polyurethane (PU)-based poly(N-vinylpyrrolidone) (PNVP)-b-PU-b-PNVP and poly(N-isopropylacrylamide) (PNIPAM)-b-PU-b-PNIPAM triblock copolymers have successfu...

The review reports an aqueous solution behavior of commercially available and easy-to-use polymers, i.e., Pluronics®- and PNIPAM-based block copolymers. Both the polymers are stimuli responsive in nature. The present review covers the different aspects of aggregation behavior of Pluronics®- and PNIPAM-based block copolymeric micelles. Here, a comparison of physical properties such as EO–PO block, CP, CMC and CMT is made. Such physical parameters can be modulated with ease by the presence of external stimuli, viz. electrolytes, organic additives such as alcohols, phenols, amides and acids, different types of surfactants and water-soluble polymers, and also by modification of end groups of Pluronics®. But in this review, our main focus is to study the addition of salts and non-electrolytes on the aggregation behavior of Pluronics®. With the help of above parameters, users can get idea about the stability, partition coefficient, solubilization capacity, etc. In analogy with Pluronics®, PNIPAM is also a thermo-responsive polymer with ~ 32 °C lower critical solution temperature (LCST). However, the LCST is independent of the degree of polymerization, i.e., molecular weight of homopolymer. However, the LCST can be tuned in the presence of external stimulus. PNIPAM-based di-block copolymers form various morphologies in different environments. An inverted morphology by double-hydrophilic-block copolymers is also possible. According to US and British Pharmacopoeia, some of the Pluronics® and PNIPAM are recognized as pharmaceutical excipients. Therefore, they have been extensively used for various pharmaceutical formulations. The other applications of these polymers are tissue engineering, bioseparation devices, active membranes, biosensors, rheological modifier, lithium batteries, etc.

In this article, a numerical scheme is introduced for solving the fractional partial differential equation (FPDE) arising from electromagnetic waves in dielectric media (EMWDM) by using an efficient class of finite difference methods. The numerical scheme is based on the Hermite formula. The Caputo's fractional derivatives in time are discretized by a finite difference scheme of order $\mathcal{O}(k^{(4-\alpha)})$ \& $\mathcal{O}(k^{(4-\beta)})$, $1, Comment: Some major revision needed

In this study we have explored the fluorescence based applications of luminescent pyrene-tagged PNVP (PyPNVP) reported in our previous work (Int. J. Polym. Mater. Polym. Biomater. 2016, 65, 269-276). PyPNVP has successfully acted as "turn off" chemosensor for metal ions Cu

A novel, water-soluble, luminescent anthracene-bridged AA-type bi-arm poly(N-vinylpyrrolidone) (ATC-PNVP) was synthesized using a click reaction between alkyne-terminated PNVP and 9,10-bis(azidomethyl)anthracene. The resultant anthracene-bridged PNVP (ATC-PNVP) was characterized using 1H NMR, FTIR, UV-Vis, and fluorescence spectroscopic methods and GPC analysis. ATC-PNVP showed effective fluorescence properties in an aqueous medium. It showed highly selective "turn off" sensing behaviour towards picric acid, a common nitro-aromatic explosive, with a wide linear range of detection of 0.01-0.3 mM and LOD value of 0.006 mM in water. ATC-PNVP-based paper sensors also showed very effective detection of picric acid in the concentration range 0.001-1.0 mM. Its binding with bovine serum albumin (BSA) was studied using steady-state, synchronous and 3D fluorescence spectroscopy and this study showed effective quenching of the intrinsic fluorescence of BSA and occurrence of a FRET-type interaction. Furthermore, this luminescent ATC-PNVP was efficiently used as a fluorescence microscopy labelling agent in NIH-3T3 and HeLa cells, and showed greater uptake and hence better fluorescent labelling in the cytosols of the tested cells than free 9,10-bis(azidomethyl) anthracene. The cell viability study also showed a very good biocompatible and non-toxic nature of ATC-PNVP at lower working concentrations towards each of the types of cells tested.

The present study was aimed to examine the interaction of two bile salts viz. sodium cholate (NaC) and sodium deoxycholate (NaDC) with three ethylene polyoxide-polypropylene polyoxide (PEO-PPO-PEO) triblock copolymers with similar PPO but varying PEO micelles with a focus on the effect of pH on mixed micelles. Mixed micelles of moderately hydrophobic Pluronic® P123 were examined in the presence of two bile salts and compared with those from very hydrophobic L121 and very hydrophilic F127. Both the bile salts increase the cloud point (CP) of copolymer solution and decreased apparent micelle hydrodynamic diameter (Dh). SANS study revealed that P123 forms small spherical micelles showing a decrease in size on progressive addition of bile salts. The negatively charged mixed micelles contained fewer P123 molecules but progressively rich in bile salt. NaDC being more hydrophobic displays more pronounced effect than NaC. Interestingly, NaC shows micellar growth in acidic media which has been attributed to the formation of bile acids by protonation of carboxylate ion and subsequent solubilization. In contrast, NaDC showed phase separation at higher concentration. Nuclear Overhauser effect spectroscopy (NOESY) experiments provided information on interaction and location of bile salts in micelles. Results are discussed in terms of hydrophobicity of bile salts and Pluronics® and the site of bile salt in polymer micelles. Proposed molecular interactions are useful to understand more about bile salts which play important role in physiological processes.

The present article is devoted to develop a new approach and methodology to find the approximate solution of second order two-dimensional telegraph equations with the Dirichlet boundary conditions. We first transform the telegraph equations into equivalent partial integro-differential equations (PIDEs) which contain both initial and boundary conditions and therefore can be solved numerically in a more appropriate manner. Operational matrices of integration and differentiation of Bernoulli polynomials together with the completeness of these polynomials are used to reduce the PIDEs into the associated algebraic generalized Sylvester equations which can be solved by an efficient Krylov subspace iterative (i.e., BICGSTAB) method. The efficiency of the proposed method has been confirmed with several test examples and it is clear that the results are acceptable and found to be in good agreement with exact solutions. We have compared the numerical results of the proposed method with radial basis function method and differential quadrature method. Also, the method is simple, efficient and produces very accurate numerical results in considerably small number of basis functions and hence reduces computational effort. Moreover, the technique is easy to apply for multidimensional problems.

Background: Aroylindole derivatives, the structural analogs of Combretastatin A-4 has been found to possess potent growth inhibitory activity on several cancer cell lines due to its excellent antitumor and antivascular activities. The aim of present research work is to identify lead and establish structure activity correlation of trimethoxyaroylindole derivatives, using integrated ligand and structure based computational approaches. Materials and Methods: A correlation between structure and biological activity was established using computational approaches i.e., structure activity correlation by pharmacophore and atom based 3D QSAR, molecular docking and energetic based pharmacophore mapping studies of trimethoxyaroylindole derivatives. Results and Discussion: The 3D-QSAR on trimethoxyaroylindole derivatives generated and showed best statistical result for CPHs AAARR.182 was validated by Q2 (0.6929), R2 (0.82). The Comp. 1 of the training set was employed as template for hydrogen bond donor, hydrophobic and hydrogen bond acceptor field prediction features and visualization of the 3D-QSAR model provides details of relationship between structure and biological activity of trimethoxyaroylindole derivatives. Pharmacophore model was developed by Phase and e-pharmacophore on comp. 1, the trimethoxy group with ring A, keto group, N-H group with ring B and ring C are pharmacophoric group important for the lead generation and coincide with various chemical features that may facilitate non-covalent binding between the ligand and its target receptor. Molecular docking studies showed critical interactions between Cys241, Val318 and meta, para-methoxy group at ring A while and Thr179 and NH of indole (distance 3.5 Å). The para position of trimethoxyphenyl ring bind to SH group of CYS 241 receptor molecule via hydrogen bond. Conclusion: The lead identification and establish structure activity correlation of trimethoxyaroylindole derivatives, were performed using integrated ligand and structure based computational approaches i.e., atom based 3D QSAR and pharmacophore study, molecular docking, energetic based pharmacophore mapping studies showed promising results. The outcomes of present studies could be utilized for the design of novel aroylindole derivatives including its lead optimization as potential anticancer agent.

In this article, we deal with a numerical wavelet collocation method (NWCM) using a technique based on two-dimensional wavelets (TDWs) approximation proposed for the fractional partial differential equations (FPDEs) for electromagnetic waves in dielectric media (EWDM). By implementing the RiemannLiouville fractional derivative, TDWs approximation and its operational matrix along with collocation method are utilized to reduce FPDEs firstly into weakly singular fractional partial integro-differential equations (FPIDEs) and then reduced weakly singular FPIDEs into system of algebraic equation. Using Legendre wavelet approximation (LWA) and Chebyshev wavelet approximation (CWA), we investigated the convergence analysis and error analysis of the proposed problem. Finally, some examples are included for demonstrating the efficiency of the proposed method via LWA and CWA respectively.

In this paper, we propose and analyze an efficient matrix method based on shifted Legendre polynomials for the solution of non-linear volterra singular partial integro-differential equations(PIDEs). The operational matrices of integration, differentiation and product are used to reduce the solution of volterra singular PIDEs to the system of non-linear algebraic equations. Some useful results concerning the convergence and error estimates associated to the suggested scheme are presented. illustrative examples are provided to show the effectiveness and accuracy of proposed numerical method.

The current study is presented to develop two approaches and methodologies to find the numerical solution of linear and non-linear initial value problems such as Lane–Emden type equation, Riccati’s equation and Bessel’s equation of order zero based on approximation. The function approximations (scheme-I and scheme-II) are presented to find the numerical solutions of linear and non-linear initial value problems by using Gauss Legendre roots as node points and random node points in the domain [0, 1]. In the scheme-I, the roots of Legendre polynomial are used as node points for Lagrange polynomials and in scheme-II, we have taken random node points in the domain [0, 1] and orthogonalize the resulting Lagrange polynomials using Gram–Schmidt orthogonalization process. Firstly, we have introduced the function approximations by using generating interpolating scaling functions (ISF) and orthonormal Lagrangian basis functions (OLBF) over the space $$L^{2}[0,1]$$ then we have constructed the operational matrices of integration and product operational matrices based on newly designed approximations namely ISF and OLBF. These operational matrices convert given linear and non-linear initial value problems into the associated system of algebraic equations. Finally, we have established error bounds (Lemmas 1, 2) of both scheme-I and scheme-II including the function approximations. The efficiency of the proposed schemes has been confirmed with several test examples including numerical stability. So, the schemes are simple, efficient and produces very accurate numerical results in considerably small number of basis functions and hence reduces computational effort.

Pluronics® and Tetronics® are used in industry for solubilizing various kinds of hydrophobic compounds since decades. In present study, moderately hydrophobic linear and star block copolymer viz. Pluronic® P104 and Tetronic® T1304 are employed for the solubilization of four polycyclic aromatic hydrocarbons (PAHs) viz. naphthalene (Np), anthracene (An), phenanthrene (Ph) and pyrene (Py). The aggregation behaviour of these block copolymers in an aqueous media has been investigated by cloud point (CP), viscometry, dynamic light scattering (DLS), and small angle neutron scattering (SANS) techniques. The aqueous solubilities of these PAHs are quite poor, hence their extractions from contaminated areas are difficult. Cloud point of block copolymers linearly decreases as a function of PAHs concentration and strongly depends on the structure of PAHs. The aqueous solutions of both block copolymers are Newtonian fluid. The solubilization of PAHs in these copolymeric micelles leads to increase in the viscosity of solution suggesting the growth of micelles. The effect of concentration and temperature on the size and shapes of micelles were evaluated from DLS and SANS studies. The study provides an alternative method for the remediation of PAHs using inexpensive commercially available block copolymers.

In this paper, a numerical solution of fractional partial differential equations (FPDEs) for electromagnetic waves in dielectric media will be discussed. For the solution of FPDEs, we developed a numerical collocation method using an algorithm based on two-dimensional shifted Legendre polynomials approximation, which is proposed for electromagnetic waves in dielectric media. By implementing the partial Riemann–Liouville fractional derivative operators, two-dimensional shifted Legendre polynomials approximation and its operational matrix along with collocation method are used to convert FPDEs first into weakly singular fractional partial integro-differential equations and then converted weakly singular fractional partial integro-differential equations into system of algebraic equation. Some results concerning the convergence analysis and error analysis are obtained. Illustrative examples are included to demonstrate the validity and applicability of the technique. Copyright © 2017 John Wiley & Sons, Ltd.

In this study we have explored the fluorescence based applications of luminescent pyrene-tagged PNVP (PyPNVP) reported in our previous work (Int. J. Polym. Mater. Polym. Biomater. 2016, 65, 269−276). PyPNVP has successfully acted as “turn off” chemosensor for metal ions Cu2+, Hg2+, and Pb2+. It has also successfully acted as a fluorescent probe for critical micellar concentration (CMC) determination of amphiphilic block copolymer of poly(d,l-lactide) and poly(N-vinylpyrrolidone) (PDLLA42-b-PNVP120) (Mn = 19 400 g/mol and PD = 1.52). It has also successfully shown an interaction with both plasmid and calf thymus (CT) deoxyribonucleic acids (DNAs) as evidenced by its fluorescence quenching. A different magnitude and type of quenching has been observed for both the cases which may be useful in distinguishing different kinds of DNAs. In order to further understand the potential of PyPNVP in various biotechnological processes, its binding property with bovine serum albumin (BSA) has also been studied. The effi...

Aqueous solution behaviour of worm-like micelles of cetyltrimethylammonium tosylate (CTAT) was examined in the presence of some water soluble nonionic polymers viz. poly(ethylene oxide) 4000 (PEO 4K), poly(propylene oxide) 1000 (PPO 1K), poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) and poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) (PPO-PEO-PPO) type linear triblock copolymers and nonlinear octablock copolymers by an array of techniques. CTAT forms worm-like micelles at very low concentrations. Very hydrophilic PEO 4K molecules surround micelle surface leading to viscosity increase while PPO 1K and linear triblock copolymers demonstrates distinct interaction with worm-like CTAT micelles. They form smaller mixed micelles strongly depending on their structure and hydrophobicity. Structurally different PEO-PPO-PEO type nonlinear block copolymer display dissimilar effect on morphology of CTAT micelles. Small angle neutron scattering (SANS) measurements provide clear idea about structural transitions from worm-like to spherical/ellipsoidal micelles with different dimensions. The different behaviour shown by the polymers is explained on the basis of their interaction with different interiors of CTAT micelles. 1 H NMR and nuclear overhauser enhancement spectroscopy (NOESY) experiments provide idea about location of these additives and site of interaction. The present study validates how the size of worm-like micelles can easily be tuned up by different polymers.

In this paper, an effective numerical method is introduced for the treatment of Volterra singular partial integro-differential equations. They are based on the operational and almost operational matrix of integration and differentiation of 2D shifted Legendre polynomials. The methods convert the singular partial integro-differential equation in to a system of algebraic equations. Convergence analysis and error estimates are derived for the proposed method. Illustrative examples are included to demonstrate the validity and applicability of the technique.

Background: Nanoparticles modulate several physiochemical and biological properties. In this regard, silver nanoparticles (AgNPs) have shown remarkable applications. The present research work comprises green synthesis of AgNPs using aqueous leaves extract of Eranthemum pulchellum and evaluation of its efficacy as antifungal and antioxidant agents. Methods: Synthesized AgNPs have been characterized by Fourier Transforms Infrared (FTIR) Spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and ultraviolet-visible spectrophotometry. Qualitative phytochemical analysis of aqueous leaves extract of E. pulchellum and FTIR spectrum of the synthesized AgNPs suggest about the presence of different phytochemicals and functional groups, respectively, which are responsible for reducing silver ions as well as capping and stabilizing synthesized nanoparticles. Results: The wavelength of maximum absorbance of AgNPs solution near to 439 nm indicates the spherical morphology. XRD infers about average crystalline size of the synthesized AgNPs to be ~12 nm. Selected area electron diffraction pattern of the synthesized AgNPs shows four visible diffraction rings corresponding to (111), (200), (220), and (311) set of planes which are attributed to face centered cubic metallic silver. The size and spherical shape of the synthesized AgNPs have been further determined by TEM. The synthesized AgNPs have shown a significant antifungal activity against Aspergillus flavus (AF-LHP-NS7) strain with minimum inhibitory concentration value of 200 μg/mL. The synthesized AgNPs have also shown strong antioxidant efficacy through Azino-bis-3-ethylbenzothiazoline-6-sulfonic acid assay with IC50 value of 462.56 μg/mL. Conclusions: The present study shows a green and facile synthesis of AgNPs. Leaves extract of E. pulchellum has been first time utilized as efficient reductant for the AgNPs synthesis. These AgNPs have shown potent antifungal and antioxidant activity.

In this article, we have study a 2D Legendre and Chebyshev wavelets collocation scheme for solving a class of linear and nonlinear weakly singular Volterra partial integro-differential equations (PIDEs). The scheme is based on wavelets collocation for PIDEs with uniquely designed matrices over the Hilbert space defined on the domain $$\left( [0, 1]\times [0, 1]\right) $$ . Using piecewise approximation associated with 2D Legendre wavelet, 2D Chebyshev wavelet and its operational matrices, the considered PIDEs will be reduced into the corresponding system of linear and nonlinear algebraic equations. The corresponding linear and nonlinear system of equations solved by collocation scheme and well-known Newton–Raphson scheme at collocation points respectively. In addition, the convergence and error analysis of the numerical scheme is provided under several mild conditions. The numerical results are correlated with the exact solutions and the execution of the proposed scheme is determined by estimating the maximum absolute errors, $$l_{2}\hbox {-}norm$$ errors and $$l_{\infty }\hbox {-}norm$$ errors. The numerical result shows that the scheme is simply applicable, efficient, powerful and very precisely at small number of basis function. The main important applications of the proposed wavelets collocation scheme is that it can be applied on linear as well as nonlinear problems and can be applied on higher order partial differential equations too.

Azide-terminated xanthate RAFT agent (S)-2-(4-azidobutyl propionate)-(O-ethyl xanthate) has been synthesized and used for the controlled radical polymerization of N-vinylpyrrolidone (NVP). Kinetics study showed the pesudo first-order kinetics along with gradual increase in molecular weight (Mn) of the resulted polymer up to 69% conversion. Chain-end analysis of the resulted polymer by 1H NMR showed the presence of the fragments of xanthate mediator at both chain ends. Successful chain extension has also been performed via the click reaction of alkyne-terminated PNVP with azide-terminated PNVP. Moreover, fluorescence pyrene-tagged PNVP has successfully been made via the click reaction of alkyne-functionalized pyrene with azide-terminated PNVP.

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 neutron scattering (SANS) measurements. A negative value of interaction parameter (β) evaluated from surface tension measurements is a signature of strong synergistic interaction between oppositely charged surfactants. Other micellar parameters have also been calculated at different mole fractions. Both the bile salts induced a shape transitions in 12-4-12 micelles on account of their hydrophobicity. Viscosity measurements disclose that loading of bile salts induces morphological changes in gemini micelles; NaDC is more efficient in altering the aggregation behaviour compared to NaC and presents a pronounced increase in viscosity and micellar growth which is suppressed at elevated temperatures. A remarkable growth observed in micelles in the presence of NaDC at low pH has been ascribed to the solubilization of bile acids formed in acidic medium. The size and shape of gemini mixed micelles obtained from SANS measurements are explicated on the basis of the hydrophobicity of bile salts. The location of bile salts in the micelle was determined from NOESY. The present study characterizes gemini–bile salt mixed systems which significantly enriches our knowledge and such a structural transition provides an opportunity to use these bioamphiphiles (bile salt containing mixed micelles) as delivery vehicles and in some pharmaceutical formulations.

The micellar characteristics of an aqueous solution of the polyoxyethylene based alkyl aryl type non-ionic surfactant Triton X-100 (TX-100) in the presence of several 1-alkyl-3-methylimidazolium (Cnmim+) based non-amphiphilic, amphiphilic and biamphiphilic ionic liquids (ILs) varying in the alkyl chain length of the cation (C4–C10) and different anions viz. chloride [Cl−], tetrafluoroborate [BF4−], trifluoromethanesulfonate [CF3SO3−], hexaflurophosphate [PF6−] and octylsuphate [C8SO4−] have been systematically investigated by cloud point (CP), viscosity, dynamic light scattering (DLS), nuclear magnetic resonance (NMR), fluorescence and small-angle neutron scattering (SANS) measurements. These ILs interact with TX-100 micelles on account of their hydrophobicity; ILs with a hydrophilic counter ion (Cl−) favour demicellization, increase CP, decrease the solution viscosity and apparent hydrodynamic diameter (Dh) of micelle, whereas ILs with a hydrophobic counter ion (PF6−) increase the solution viscosity and exhibit micellar growth. SANS data on the size/shape of TX-100 micelles in the presence of different ILs are reported to provide information on microstructural changes in the micelles. The location of ILs, which has a dominating effect on the structure of the micelles, was evaluated using fluorescence and 1H NMR studies, and these results are discussed in terms of the insertion of the ILs in TX-100 micelles. IL molecules with long alkyl chains penetrate deeper in the TX-100 micelles. The present study provides useful information on tuning the solution characteristics of TX-100 in the presence of ILs that may have industrial applications.

Mono- and multinuclear complexes of ruthenium and [n]cycloparaphenylene (CPP, n = 5 and 6) were synthesized in excellent yields through ligand exchange of the cationic complex [(Cp)Ru(CH3CN)3](PF6) with CPP. In the multinuclear complexes, ruthenium selectively coordinated to alternate paraphenylene units to give bis- and tris-coordinated Ru complexes for [5] and [6]CPPs, respectively. Single-crystal X-ray analysis revealed the Ru was coordinated with η(6)-hapticity on the convex surface of CPP.

A selective, practical, and large-scale synthesis of [6]cycloparaphenylene, the second smallest cycloparaphenylene to be synthesized, was achieved in nine steps starting from commercially available 1, 4-dibromobenzene and 4′-bromobiphenyl-4-ol. The key intermediate, cis-1, 4-(4-bromophenyl)-1, 4-bis(triethylsiloxy)cyclohexa-2, 5-diene, was prepared on a large scale (>20 g) and was selectively dimerized to form a cyclic precursor of [6]cycloparaphenylene by platinum-mediated assembly and subsequent reductive elimination. Deprotection of the triethylsilyl group and subsequent tetrachlorostannic acid (H2SnCl4)-mediated reductive aromatization gave [6]cycloparaphenylene in 23% overall yield from the commercially available substrates on gram scale.

Cyclic precursors of cycloparaphenylenes (CPPs) containing 1,4-dihydroxy-2,5-cyclohexadien-1,4-diyl units are prepared by modifying a synthetic method developed by Jasti and co-workers for the synthesis of corresponding 1,4-dimethoxy derivatives. Reductive aromatization of the diyl moieties by SnCl2/2 HCl takes place under mild conditions and affords the CPPs in good yields, incorporating 5 or 7-12 phenylene units. Highly strained [5]CPP is synthesized in greater than 0.3 g scale. (119)Sn NMR spectroscopy clarifies the in situ formation of an ate complex, H2SnCl4, upon mixing a 2:1 ratio of HCl and SnCl2, which serves as a highly active reducing agent under nearly neutral conditions. When more than 2 equivalents of HCl, in relation to SnCl2, are used, acid-catalyzed decomposition of the CPP precursors takes place. The stoichiometry of HCl and SnCl2 is critical in achieving the desired aromatization reaction of highly strained CPP precursors.

The cationic surfactant cetyltrimethylammonium tosylate (CTAT) forms highly viscous/viscoelastic solutions and worm-like micelles at relatively low concentrations. The effect of 1-alkanols with short to long alkyl chains viz. ethanol, 1-butanol, 1-hexanol and 1-octanol on CTAT micelles was examined. In particular, a detailed study on the effect of 1-hexanol was carried out by viscosity, cryogenic transmission electron microscopy (cryo-TEM), nuclear magnetic resonance (NMR) and small-angle neutron scattering (SANS) to observe microstructural changes in CTAT micelles. 1-Hexanol displays a distinct interaction with CTAT micelles strongly dependent on CTAT concentration. Up to a certain critical CTAT concentration, 1-hexanol molecules penetrate into the micelles and show growth. Characterization by direct cryo-TEM imaging implies that upon progressive addition of 1-hexanol, worm-like CTAT micelles first grow and finally transform into vesicles. The course of vesicle formation was followed by SANS measurements. The site of 1-hexanol in the micelles close to the palisade layer was evaluated using 2D NMR. This study devotes a fundamental knowledge for controlling the shape and size of worm-like micelles that find many industrial applications particularly in personal- and home-care products.

Tadpole-shaped β-cyclodextrin-tagged poly(N-vinylpyrrolidone) (β-CD-PNVP) has been synthesised via the click reaction of alkyne-terminated PNVP and azide-functionalized β-CD. The formed polymer is characterized by 1H NMR, FTIR, and TGA study. The complexing ability of such a polymer with phenolphthalein is considerably lower with respect to that with β-CD alone. Doxorubicin (DOX)-loaded β-CD-PNVP (DOX-β-CD-PNVP) exhibits higher tumoricidal activity against a panel of tumor cell lines derived from sarcoma (U2-OS) and carcinomas (MCF-7 and HEPG2), causing significant lysis of tumor cells compared to free DOX. The formulation also demonstrates significantly higher uptake by the tumor cells and enhances apoptosis compared to free DOX.

A nanohybrid has been synthesized by incorporating organically modified layered silicate in a poly(vinylidene fluoride) (PVDF) matrix. Molecular-level phenomena have been explored after exposing PVDF and its nanohybrid to an electron beam of varying doses. The electron beam interacts with polymer chains and thereby generates different free radicals, the number of which is quite high in nanohybrid as compared to pure PVDF. The stability of free radicals has been confirmed through density functional theory energy minimization, predicting stable β-phase free radicals in the nanohybrid. Quantitative analyses of chain scission, crosslinking and double bond formation are reported and compared after irradiation for both PVDF and its nanohybrid using UV-visible and Fourier transform infrared spectroscopies, sol–gel analyses and gel permeation chromatography, revealing both chain scission and crosslinking phenomena in irradiated PVDF and its nanohybrid, but at higher dose (>90 Mrad) crosslinking dominates in the nanohybrid due to more free radicals and proximity of radical chains on top of templated system in the nanohybrid as compared to pure PVDF. The enhanced crosslinking alters the nanostructure causing disappearance of the peak at 2θ ≈ 3°. Moreover, the electron beam induces significant piezoelectric β-phase in the nanohybrid against only α-phase in pure PVDF at a similar dose and raises the possibility for the use of electron-irradiated nanohybrid as an electromechanical device. β-Phase formation is also supported through solid-state NMR, scanning electron microscopy and differential scanning calorimetry studies. The thermal properties in terms of heat of fusion and degradation temperature have been verified indicating steady decrease of melting point and heat of fusion for pure PVDF while considerably less effect is observed for the nanohybrid. The combined effect of chain scission and crosslinking makes both PVDF and its nanohybrid brittle, but with greater stiffness with respect to unirradiated specimens. © 2014 Society of Chemical Industry

Well-defined linear dihydrophilic amphiphilic ABA-type triblock copolymers of e-caprolactone (CL) and N-isopropylacrylamide (NIPAAm) have successfully been synthesized with a high yield by combining the ring opening polymerization (ROP) and xanthate-mediated reversible addition-fragmentation chain transfer (RAFT) polymerization methods. The resulted block copolymer shows the formation of micelles in water as supported by light scattering. The critical micelle concentration (cmc) value of the micelle increases with the increase in the chain length of the poly (N-isopropylacrylamide) (PNIPAAm) block. Cloud point of the block copolymers decreases with the decrease in the PNIPAAm chain length. The TGA analysis shows a one-step degradation and a lower thermal stability of the triblock copolymer than the PNIPAAm. The DSC analysis of the triblock copolymer shows the lowering of glass transition temperature (T g), and melting temperature (T m) peaks possibly due to the partial miscibility of the poly (e-caprolactone) (PCL) block with the amorphous PNIPAAm block through the interaction of ester groups of PCL with the amide groups of PNIPAAm. The XRD pattern of the triblock copolymer shows a broad peak due to the suppression of the crystallization of PCL block owing to the mixing of PNIPAAm block with the PCL block.

Well-defined amphiphilic poly( d , l -lactide)- b -poly( N -vinylpyrrolidone) (PDLLA- b -PNVP) block copolymers were successfully prepared using ring-opening polymerization (ROP) and xanthate-mediated reversible addition-fragmentation chain transfer (RAFT) polymerization. Synthesized PDLLA- b -PNVP block copolymers were characterized by 1 H NMR spectroscopy and GPC. Spherical micelles of ∼30.2 nm diameter were formed from the aqueous solution of amphiphilic diblock copolymer PDLLA 42 - b -PNVP 63 as revealed by TEM and supported by 1 H NMR and light scattering. The critical micelle concentration value of the block copolymers, determined by fluorescence spectroscopy using pyrene as probe, increased with the increase in the chain length of PNVP block. The average hydrodynamic radius ( R h ) of the micelles remained almost constant above the cmc value over the angles of scattering measurement. Thermal properties of these block copolymers were studied by TGA, DTA and DSC. Crystalline properties of these block copolymers were studied by WXRD.

Two new alkyne-terminated xanthate reversible addition-fragmentation chain-transfer (RAFT) agents: (S)-2-(Propynyl propionate)-(O-ethyl xanthate) (X3) and (S)-2-(Propynyl isobutyrate)-(O-ethyl xanthate) (X4) were synthesized and characterized and used for the controlled radical polymerization of N-vinylpyrrolidone (NVP). X3 showed better chain transfer ability in the polymerization at 60°C. Molecular weight of the resulted polymer increased linearly with the increase in monomer loading. Kinetics study with X3 showed the pseudo-first order kinetics up to 67% monomer conversion. Molecular weight (Mn) of the resulting polymer increased linearly with the increase in the monomer conversion up to around 67%. With the increase in the monomer conversion, polydispersity of the corresponding poly(NVP)s initially decreased from 1.34 to 1.32 and then increased gradually to 1.58. Chain-end analysis of the resulting polymer by 1H-NMR and FTIR showed clearly that polymerization started with radical forming out of xanthate RAFT agent. Living nature of the polymerization was also confirmed from the successful homo-chain extension experiment and the hetero-chain extension experiment involving synthesis of poly(NVP)-b-polystyrene amphiphilic diblock copolymer. Formed alkyne-terminated poly(NVP) also allowed easy conjugation to azide-terminated polystyrene by click chemistry to prepare well-defined poly(NVP)-b-polystyrene block copolymers. Resulting polymers were characterized by GPC, 1H-NMR, FTIR, and thermal study. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Poly(N-isopropylacrylamide) (PNIPAM) hydrogels and the corresponding linear homopolymers were synthesized in different methanol-water mixtures (x(m) = 0, 0.13, 0.21, 0.31, 0.43, 0.57, and 0.76, where x(m) is the mole fraction of methanol) in the presence of 0.1 M Y(OTf)(3) Lewis acid. The isotacticity (meso dyad (m), %) and cloud-point temperature of these homopolymers were gradually increased and decreased, respectively, with the increase in the x(m) values of the synthesis solvent mixtures. Moreover, the corresponding linear PNIPAM homopolymers prepared in the absence of Y(OTf)(3) showed an almost constant isotacticity of m = 45% and a cloud-point temperature of 33.0 °C. A SEM study revealed that the resulting hydrogels were highly porous except for the gels prepared at x(m) = 0 and 0.76. The swelling ratios of these hydrogels in water at different temperatures and in different methanol-water mixtures at 20 °C and the deswelling rate and the reswelling rate of these hydrogels were studied. All of these swelling results were compared with that of the corresponding gels prepared in the absence of a Lewis acid (Biswas, C. S.; Patel, V. K.; Vishwakarma, N. K.; Mishra, A. K.; Bhimireddi, R.; Rai, R.; Ray, B. J. Appl. Polym. Sci.2012, DOI: 10.1002/app.36318) and explained on the basis of the porosity of the gel, the state of aggregation and isotacticity of the PNIPAM chain segment, and the cononsolvency of the methanol-water mixture toward the PNIPAM chain segment.

S)-2-(Ethyl propionate)-(O-ethyl xanthate) (X1) and the newly syn- thesized (S)-2-(ethyl isobutyrate)-(O-ethyl xanthate) (X2) were used as the revers- ible addition-fragmentation chain transfer (RAFT) agents for the radical polymerization of N-vinylpyrrolidone (NVP). The former showed the better chain transfer ability in the polymerization at 60 C. Kinetics study with X1 shows the psuedo-first order kinetics upto 45% monomer conversion. Molecular weight (Mn) of the resulted polymer increases linearly with increase in the monomer conversion upto around 45%. Polydispersity of the corresponding poly(NVP)s increase grad- ually from 1.2 to 1.9 with increase in the monomer conversion. Chain-end analysis of the resulted polymer by 1 H NMR shows clearly that polymerization started with radical forming out of xanthate mediator. Living nature of the polymerization was confirmed from the successful homo chain extension experiment and also the het- ero-chain extension experiment involving synthesis of poly(NVP)-b-polystyrene amphiphilic diblock copolymer.

Poly(N-isopropylacrylamide) (PNIPAM) hydrogels were simply prepared by free radical polymerization in different methanol–water mixture. A scanning electron microscopy study revealed that the freeze-dried hydrogels were macroporous. The swelling ratios in water at 20°C of the resulting hydrogels followed the order: X0.43>X0.21>X0.76 ≈ X0.57>X0.31>X0.13>X0.06>X0, where Xm denotes a gel prepared in a methanol–water mixture with m mole fraction of methanol (xm). Below the lower critical solution temperature, the swelling ratio values of all of the hydrogels gradually decreased with the increase in the temperature. The complete collapse of the PNIPAM chain of all the gels occurred at about 38°C, whereas the same was observed at about 35°C for the conventional gel prepared in water. The swelling ratio values of all the PNIPAM gels in the methanol–water mixtures with different xm values at 20°C passed through a minimum in the cononsolvency zone. The deswelling rates of the hydrogels decreased in the following order: X0.43> X0.31> X0.21> X0.57> X0.76 ≈ X0.13> X0.06> X0. The reswelling rates of these hydrogels decreased in the following order: X0> X0.31> X0.06 ≈ X0.13 > X0.76> X0.57> X0.21> X0.43. The release rates of the Tramadol Hydrochloride drug at 37°C from the drug-loaded hydrogels were almost same for all of the hydrogels. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012