Sudip Pattanayek - Academia.edu (original) (raw)

Papers by Sudip Pattanayek

Journal of Chemical Physics, Jul 15, 2005

We study a system of grafted semiflexible polymers in a poor solvent which form toroidal or rodli... more We study a system of grafted semiflexible polymers in a poor solvent which form toroidal or rodlike conformations in the bulk. However, because of the physical constraint of surface grafting, macrophase separation is inhibited and a number of different polymer aggregates (or micelles) form which can be related to the chains&amp;#39; stiffness and their affinity for each other. In contrast to the fully flexible Gaussian case, we observe a number of novel micelle structures, including tower micelles, archway micelles, and spider micelles. We also attempt to develop a phase diagram for the occurrence of these structures with respect to the variables of chain length, chain stiffness, and polymer grafting density.

Analytical Chemistry, May 18, 2023

Journal of Molecular Liquids, Dec 1, 2016

Abstract The possibility of utilizing the lyotropic Chromonic Liquid Crystal (LCLC) in the detect... more Abstract The possibility of utilizing the lyotropic Chromonic Liquid Crystal (LCLC) in the detection of the biological cells, such as bacteria, virus etc. and biological macromolecules like protein, DNA etc. have attracted a number of researchers in recent time. The organization of the LCLC near surfaces is important to explore these applications. We have explored the time-dependent effects of surface re-arrangements of LCLCs (disodium chromo glycate (DSCG) and Sunset Yellow (SSY)) using the polarized microscope. It is found that the initial arrangement of DSCG and SSY depends on the hydrophobicity of the surface. A strong hydrophobic surface leads to the homeotropic arrangements of DSCG and SSY. However, the moderately hydrophobic surface cannot give the homeotropic arrangements of LCLCs. With the passage of time, the evolved texture of the LCLCs is independent of surface hydrophobicity. The effect of surfaces on DSCG is more pronounced compared to that on SSY.

Journal of Polymer Science Part B, 2007

A polymer chain in a poor solvent collapses to a spherical globule. If this globule is subsequent... more A polymer chain in a poor solvent collapses to a spherical globule. If this globule is subsequently deformed, either by stretching it or if it has some non‐zero net electric charge, it will become unstable to sinusoidal perturbations leading to novel final states. When such globules are imaged by direct methods such as atomic force microscopy the substrate on which they adsorb can affect the final morphological state. We therefore investigate strongly adsorbed polymers in poor solvents. We demonstrate that the real‐space, Self‐Consistent Field method is an ideal numerical tool in predicting equilibrium morphologies. New structures are predicted, which support previous explicit free energy calculations. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3327–3337, 2007

Industrial & Engineering Chemistry Research, Jan 30, 2019

Quartz crystal microbalance with dissipation (QCM-D) is used to study the adsorption characterist... more Quartz crystal microbalance with dissipation (QCM-D) is used to study the adsorption characteristics of insulin, myoglobin, bovine serum albumin and -galactosidase over amine and methyl surfaces. The water-based and D 2 O based phosphate buffers are used for making protein solution. The kinetics of adsorption data, equilibrium adsorption data and the elasticity of an adsorbed protein is obtained experimentally. A kinetic model of the adsorption of protein with surface phase concept is developed and fitted to experimental kinetic data. The kinetic parameter involving the first binding step with the surface depends on the surface and physical characteristics of the protein such as charge and component of the secondary structure. The experimental adsorption isotherms data are fitted to a multi-layer model with two equilibrium adsorption constants (K s and K L). The relative strength of adsorption over the bare surface is denoted by K s, and the relative adsorption strength of protein over the adsorbed protein is denoted by K L. A protein containing a higher amount of  content has a higher K s value during its adsorption on amine surface. The elastic component of the viscoelastic properties, G' of the adsorbed proteins is found to be high for the protein layer obtained through high K s and low K L values. The desorption kinetics of the adsorbed proteins using a surfactant solution is also investigated. The elastic properties of the adsorbed proteins and desorption characteristics of the adsorbed proteins by a surfactant (sodium dodecyl sulfate) are strongly related to the adsorption strengths determining factors K s and K L. An adsorbed protein obtained through a high K s value is difficult to remove by the surfactant solution.

Applied Surface Science, May 1, 2017

Highlights  Characteristics of SAMs are better studied with PSD.  Morphology of insulin depends... more Highlights  Characteristics of SAMs are better studied with PSD.  Morphology of insulin depends on the grain size of surfaces.  Approach of modifiers depends on the head group  The reaction of modifiers on silica surface is optimum at some intermediate conc.

Colloid and Polymer Science, May 13, 2017

Rheological properties of suspensions are influenced by changes in the particle's or suspending m... more Rheological properties of suspensions are influenced by changes in the particle's or suspending medium's traits. Due to the ability of water and cornstarch to develop strong hydrogen bonds with each other and with hydroxyl groups of other liquids, it is promising to modify the suspending media with polyols to analyze the change in the Newtonian behavior of the suspensions. Cornstarch-water suspensions were prepared by adding different polyols viz.., glycerine, ethylene glycol (EG), and polyethylene glycol (PEG) to the suspending liquid (water) at various concentrations. The presence of possible chemical interaction due to the hydroxyl groups within the water-polyol systems was confirmed by Fourier transfer infrared spectroscopy (FTIR). The rheological parameters of pure cornstarch-water suspension were compared with that of water-polyol-based shear thickening fluids (STFs). The thickening behavior enhanced by three orders of magnitude with increasing glycerine and EG content for a constant particle concentration. However, the presence of PEG in the suspension resulted in a shear thinning phenomenon with a high yield stress unlike the other polyols. Thus, the presence of O-H interactions in the suspending liquid was presumed to control the flow phenomenon of these suspensions. A possible mechanism based on interactions has been proposed for the non-Newtonian flow in each suspension. The current work is one of a kind in demonstrating the role of hydrogen interactions within suspending medium on the thickening behavior of the cornstarch-water suspensions.

Macromolecular Theory and Simulations, Jul 19, 2005

Langmuir, Nov 19, 2004

With the aim of investigating the effect of the surface properties on the friction behavior of se... more With the aim of investigating the effect of the surface properties on the friction behavior of self-assembled monolayers, we have modified tipless atomic force microscopy (AFM) cantilevers with a poly(dimethylsiloxane) (PDMS) lens. The friction coefficient using the silicon tip is strongly influenced by the mechanical properties of the substrate monolayer because hard, sharp silicon tips penetrate the surface of organic monolayers. However, the friction coefficient obtained for the PDMS-modified AFM cantilever is mostly due to the surface properties of the monolayer functional end group, rather than the viscoelastic deformation of the monolayer. The use of the PDMS tip was demonstrated as a novel means to investigate the effect of surface properties on the frictional behavior of self-assembled monolayers with various functional groups with less mechanical deformation.

Materials Chemistry and Physics, Feb 1, 2023

Colloids and Surfaces A: Physicochemical and Engineering Aspects, Feb 1, 2023

Chemical Physics Letters, Jun 1, 2018

Semi flexible polymer chain has been modeled by choosing various values of persistent length (sti... more Semi flexible polymer chain has been modeled by choosing various values of persistent length (stiffness). As the polymer chain stiffness increases, the shape of polymer chain changes from globule to extended cigar to toroid like structure during cooling from a high temperature. The aggregation of fullerene nano-particles is found to depend on the morphology of polymer chain. To maximize, the number of polymer bead-nanoparticle contacts, all nano-particle have positioned inside the polymer globule. To minimize, the energy penalty, due to bending of the polymer chain, all nano-particle have positioned on the surface of the polymer's cigar and toroid morphology.

ACS Biomaterials Science & Engineering, Aug 13, 2018

Surface modification plays vital role in regulating protein adsorption and subsequently cell adhe... more Surface modification plays vital role in regulating protein adsorption and subsequently cell adhesion. In the present work, we prepared nanoscaled modified surfaces using silanization and characterized them using Fourier-transform infrared spectroscopy (FTIR), water contact angle (WCA) and Atomic Force microscopy (AFM). Five different (amine, octyl, mixed, hybrid and COOH) surfaces were prepared based on their functionality and varying wettability and their effect on protein adsorption and initial cell adhesion was investigated. AFM analysis revealed nanoscale roughness on all modified surfaces. Fetal bovine serum (FBS) was used for protein adsorption experiment and effect of FBS was analyzed on initial cell adhesion kinetics (upto 6 h) under three different experimental conditions: (a) with FBS in media, (b) with pre-adsorbed FBS on surfaces and (c) incomplete media, i.e., without FBS. Various cell features such as cell morphology/circularity, cell area and nuclei size were also studied for above stated conditions at different time intervals. The cell adhesion rate as well as cell spreaded area were highest in case of surfaces with pre-adsorbed FBS. We observed higher surface coverage rate by adhering cells on hybrid (rate, 0.073 h-1) and amine (0.072 h-1) surfaces followed by COOH (0.062 h-1) and other surfaces under pre-adsorbed FBS condition. Surface treated with cells in incomplete media exhibited least adhesion rate, poor cell spreading and improper morphology. Furthermore, we found that initial cell adhesion rate and ∆ adhered cells (%) linearly increased with the change in α-helix content of adsorbed FBS on surfaces. Amongst all the modified surfaces and under all three experimental conditions, hybrid surface exhibited excellent properties for supporting cell adhesion and growth and hence can be potentially used as surface modifiers in biomedical applications to design biocompatible surfaces.

Journal of Nanoparticle Research, Feb 24, 2018

Materials Chemistry and Physics, Oct 1, 2023

Journal of Physical Chemistry B, Oct 8, 2019

Composites Science and Technology, Oct 1, 2016

Abstract Researchers have used molecular simulations to determine the mechanical properties of si... more Abstract Researchers have used molecular simulations to determine the mechanical properties of single walled carbon nanotube (SWCNT)-polymer nanocomposite but have not looked into composite of semi-flexible polymers. We have explored the effect of the organizations of semi-flexible polymer on mechanical properties such as elastic modulus and yield stress of the polymer-SWCNT composite. The proportions of locally ordered organization of polymer chains in a sample depend on its flexibility. For a fixed flexibility of a polymer chain, the presence of SWCNTs improves the proportion of regularly arranged polymers present in the composite. In turn, this improves the elastic modulus and yield stress of the polymer of higher rigidity. The enhancement in elastic modulus and yield stress is due to the retarded deformation of densely packed, ordered region of polymer chains in polymer/SWCNT composite. The presence of randomly oriented chains in a polymer sample containing regularly arranged polymer leads to the higher strain at yield point.

Langmuir, Mar 7, 2016

The force-induced desorption of a polymer chain from a graphene substrate is studied with Molecul... more The force-induced desorption of a polymer chain from a graphene substrate is studied with Molecular Dynamics (MD). A critical force needs to be exceeded before detachment of the polymer from the substrate. It is found for a chain to exhibit good adhesive properties the chain configuration should consist of fibrils-elongated, aligned sections of polymers and cavities which dissipate the applied energy. A fibrillation index is defined to quantify the quality of fibrils. We focus on the molecular properties of the polymer chain which can lead to large amounts of fibrillation and find both strong attraction between polymer and substrate and good solvency conditions are important conditions for this. We also vary the stiffness of the chain and find for less stiff chains a plateau in the stress-strain curve gives rise to good adhesion but for very stiff chains, there is limited elongation of the chain but the chain can still exhibit good fibrillation by a lamella-like rearrangement. Finally, it is found the detachment time, t of a polymer from the adsorbed substrate is inversely proportional to force, F , i.e. t ∝ F −γ where the exponent γ depends on solvent quality, polymer-substrate attraction and chain stiffness.