scholarly journals Tuning the Swelling Properties of Smart Multiresponsive Core-Shell Microgels by Copolymerization

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1269 ◽  
Author(s):  
Timo Brändel ◽  
Maxim Dirksen ◽  
Thomas Hellweg
Keyword(s):  
Ph Value ◽  
Single Step ◽  
Correlation Spectroscopy ◽  
Swelling Behavior ◽  
Shell Morphology ◽  
Core Shell ◽  
Swelling Properties ◽  
Force Microscopy ◽  
Atomic Force ◽  
Pure Poly

The present study focuses on the development of multiresponsive core-shell microgels and the manipulation of their swelling properties by copolymerization of different acrylamides—especially N-isopropylacrylamide (NIPAM), N-isopropylmethacrylamide (NIPMAM), and NNPAM—and acrylic acid. We use atomic force microscopy for the dry-state characterization of the microgel particles and photon correlation spectroscopy to investigate the swelling behavior at neutral (pH 7) and acidic (pH 4) conditions. A transition between an interpenetrating network structure for microgels with a pure poly-N,-n-propylacrylamide (PNNPAM) shell and a distinct core-shell morphology for microgels with a pure poly-N-isopropylmethacrylamide (PNIPMAM) shell is observable. The PNIPMAM molfraction of the shell also has an important influence on the particle rigidity because of the decreasing degree of interpenetration. Furthermore, the swelling behavior of the microgels is tunable by adjustment of the pH-value between a single-step volume phase transition and a linear swelling region at temperatures corresponding to the copolymer ratios of the shell. This flexibility makes the multiresponsive copolymer microgels interesting candidates for many applications, e.g., as membrane material with tunable permeability.

Effect of Water Temperature, pH Value, and Film Thickness on the Wettability Behaviour of Copper Surfaces Coated with Copper Using EB-PVD Technique

2019 ◽  
Vol 60 ◽  
pp. 124-141 ◽  
Author(s):  
Naser Ali ◽  
Joao Amaral Teixeira ◽  
Abdulmajid Addali
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Film Thickness ◽  
Water Temperature ◽  
Ph Value ◽  
Surface Wettability ◽  
Copper Surfaces ◽  
Force Microscopy ◽  
Atomic Force ◽  
Static Contact

This research investigates the effect of surface roughness, water temperature, and pH value on the wettability behaviour of copper surfaces. An electron beam physical vapour deposition technique was used to fabricate 25, 50, and 75 nm thin films of copper on the surface of copper substrates. Surface topographical analysis, of the uncoated and coated samples, was performed using an atomic force microscopy device to observe the changes in surface microstructure. A goniometer device was then employed to examine the surface wettability of the samples by obtaining the static contact angle between the liquid and the attached surface using the sessile drops technique. Waters of pH 4, 7, and 9 were employed as the contact angle testing fluids at a set of fixed temperatures that ranged from 20°C to 60°C. It was found that increasing the deposited film thickness reduces the surface roughness of the as-prepared copper surfaces and thus causing the surface wettability to diverge from its initial hydrophobic nature towards the hydrophilic behaviour region. A similar divergence behaviour was seen with the rise in temperature of water of pH 4, and 9. In contrast, the water of pH 7, when tested on the uncoated surface, ceased to reach a contact angle below 90o. It is believed that the observed changes in surface wettability behaviour is directly linked to the liquid temperature, pH value, surface roughness, along with the Hofmeister effect between the water and the surface in contact.

Preparation and Property Study of Core-Shell Ambient-Temperature Crosslinkable Polyacrylate Binder

2013 ◽  
Vol 469 ◽  
pp. 3-6 ◽  
Author(s):  
Mu Li ◽  
Xiao Song Lin ◽  
Xiao Yu Li ◽  
Hai Qiao Wang
Keyword(s):  
Ambient Temperature ◽  
Butyl Acrylate ◽  
Core Shell ◽  
Drying Time ◽  
Acrylic Polymer ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Film Forming ◽  
Water Based

As the binder of waterborne inks, the capability of acrylic polymer has great influences on the quality of inks. In this contribution, structured latex particles with a poly (stryrene-butyl acrylate-methacrylate) core and a poly (butyl acrylate-methyl methacrylate-methacrylic acid-diacetone acrylamide (DAAM)) shell, which can be used as binders of water-based ink, were prepared by emulsion polymerization. The emulsion can cure in the course of film forming at ambient temperature through the reaction between DAAM and the adipic acid dihydrazide (ADH). Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), transmission electron microscopy (TEM), atomic force microscopy (AFM) were used to characterize the structures and study the properties of the latices. The drying time of the crosslinking latices was investigated. In addition, influences of DAAM monomer dosage and the mole ratio of DAAM to ADH on the mechanical properties of self-crosslinkable core-shell latices were also discussed. It was found that the core-shell crosslinkable particles with a low glass transition temperature (Tg) core and a high Tg shell have better film properties and would be more applicable to binders of water-based ink for plastic film, in comparison with those particles with a high Tg core and a low Tg shell.

scholarly journals pH-depended protein shell dis- and reassembly of ferritin nanoparticles revealed by atomic force microscopy

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Lukas Stühn ◽  
Julia Auernhammer ◽  
Christian Dietz
Keyword(s):  
Atomic Force Microscopy ◽  
Ph Value ◽  
Surrounding Medium ◽  
Real Space ◽  
Iron Storage ◽  
Liquid Environment ◽  
Force Microscopy ◽  
Atomic Force ◽  
Dependent Change ◽  
Protein Shell

AbstractFerritin, a protein that is present in the human body for a controlled iron storage and release, consists of a ferrihydrite core and a protein shell. Apoferritin, the empty shell of ferritin, can be modified to carry tailored properties exploitable for targeted and direct drug delivery. This protein shell has the ability to dis- and reassemble depending on the pH value of the liquid environment and can thus be filled with the desired substance. Here we observed the dis- and reassembly process of the protein shell of ferritin and apoferritin in situ and in real space using atomic force microscopy. Ferritin and apoferritin nanoparticles adsorbed on a mica substrate exhibited a change in their size by varying the pH value of the surrounding medium. Lowering the pH value of the solution led to a decrease in size of the nanoparticles whereas a successive increase of the pH value increased the particle size again. The pH dependent change in size could be related to the dis- and reassembling of the protein shell of ferritin and apoferritin. Supplementary imaging by bimodal magnetic force microscopy of ferritin molecules accomplished in air revealed a polygonal shape of the core and a three-fold symmetry of the protein shell providing valuable information about the substructure of the nanoparticles.

A New Drug Vehicle - Lipid Coated Biodegradable Nanoparticles

2008 ◽  
Vol 57 ◽  
pp. 148-153 ◽  
Author(s):  
J. Schäfer ◽  
Johannes Sitterberg ◽  
C. Ehrhardt ◽  
M.N.V. Ravi Kumar ◽  
Udo Bakowsky
Keyword(s):  
Plga Nanoparticles ◽  
Correlation Spectroscopy ◽  
Cell Culture Model ◽  
Supported Lipid Bilayer ◽  
Photon Correlation ◽  
Force Microscopy ◽  
Coated Nanoparticles ◽  
Atomic Force ◽  
Culture Model ◽  
A Cell

The preparation and charactersiation of novel lipid coated PLGA nanoparticles was investigated in the presented study. The size of the pure nanoparticles could be adjusted in dependence on the stabilizer content. The supported lipid bilayer surrounding the nanoparticles was formed by the liposome spreading technique. The Lipid- coated nanoparticles were characterised using Photon Correlation Spectroscopy (PCS) and atomic force microscopy (AFM) investigations. The bioadhesive properties was proofed in a cell culture model.

Effect of Molarity on Structural and Optical Properties of Chemically Deposited Nanocrystalline PbS Thin Film

2017 ◽  
Vol 74 ◽  
pp. 22-35 ◽  
Author(s):  
Manash Pratim Sarma ◽  
G. Wary
Keyword(s):  
Thin Films ◽  
Ph Value ◽  
Bath Temperature ◽  
Ion Source ◽  
Complexing Agent ◽  
X Ray ◽  
Force Microscopy ◽  
Nanocrystallite Size ◽  
Atomic Force ◽  
Cbd Method

Thin films of PbS were deposited by chemical bath deposition (CBD) method under various molarities using lead acetate as Pb2+ ion source, thiourea as S2- ion source and ammonia as complexing agent at a fixed pH value of 9 under bath temperature of 333 K. Four different molarities of PbS thin films were prepared. The as-prepared films were characterized by using X-ray diffraction (XRD), X-ray fluorescence (XRF), EDX, field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). Parameters like crystallite size, lattice constant, microstrain, dislocation density were calculated. Optical constants such as extinction coefficient, absorption coefficient were measured from absorption spectra. Studies show that average nanocrystallite size increases from14.2 nm to 18.1 nm as the molarity of the film increases. Optical studies reveal the decrease of band gap from 1.75 eV to 1.44 eV with increasing molarity of the film indicating higher electrical conductivity of the films.

Measurement of Interactions between Abrasive Silica Particles and Copper, Titanium, Tungsten and Tantalum

2007 ◽  
Vol 991 ◽  
Author(s):  
Ruslan Burtovyy ◽  
Alex Tregub ◽  
Mansour Moinpour ◽  
Mark Buehler ◽  
Igor Luzinov
Keyword(s):  
Ph Value ◽  
High Sensitivity ◽  
Model Systems ◽  
Thin Polymer Film ◽  
Colloidal Probe ◽  
Force Microscopy ◽  
Atomic Force ◽  
Afm Cantilever ◽  
The Moment ◽  
Silica Slurry

ABSTRACTColloidal probe technique has been widely employed to measure the adhesion between micro- and nanosize objects using atomic force microscopy (AFM). However, majority of studies concerns model systems, which do not incorporate real abrasive particles. The approach applied allows measuring adhesion between real CMP nanoparticles and different surfaces. Thin polymer film with high affinity to the particles was used to anchor the particles to a surface. Hollow glass bead (20-30 μm) representing flat surface was attached to soft AFM cantilever. Application of large hollow bead and the cantilever with small spring constant allows measuring the interactions with high sensitivity. Titanium, tungsten and tantalum metals were sputtered on the bead surface. The effect of different factors such as pH value, concentration and type of a surfactant on adhesion between surfaces of metals and silica slurry has been studied. Character and intensity of interactions at the moment of contact have been evaluated from experimental force-distance curves.

Tapping Mode Atomic Force Microscopy Investigation of Poly(amidoamine) Core−Shell Tecto(dendrimers) Using Carbon Nanoprobes

Langmuir ◽  
2002 ◽  
Vol 18 (8) ◽  
pp. 3127-3133 ◽  
Author(s):  
Theodore A. Betley ◽  
Jessica A. Hessler ◽  
Almut Mecke ◽  
Mark M. Banaszak Holl ◽  
Bradford G. Orr ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Core Shell ◽  
Tapping Mode ◽  
Force Microscopy ◽  
Atomic Force Microscopy Investigation ◽  
Atomic Force ◽  
Microscopy Investigation ◽  
Mode Atomic Force Microscopy

Effect of pH on the Formation of a Bovine Serum Albumin Layer on a Poly(stryren-co-maleic Acid) Surface

2010 ◽  
Vol 93-94 ◽  
pp. 583-586 ◽  
Author(s):  
Tippavan Hongkachern ◽  
Verawat Champreda ◽  
Toemsak Srikhirin ◽  
Thidarat Wangkam ◽  
Tanakorn Osotchan
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Maleic Acid ◽  
Bovine Serum ◽  
Quartz Crystal ◽  
Ph Value ◽  
Layer Formation ◽  
Force Microscopy ◽  
Ph Values ◽  
Atomic Force

The layer formation of bovine serum albumin (BSA) on a poly(styrene-co-maleic acid) (PSMA) surface was investigated by using quartz crystal microbalance (QCM) technique at various pH values. The formation of a BSA surface was examined by atomic force microscopy (AFM). To study the effect on the layer formation, the pH of solution was varied from 2 to 7.4 while the concentration of BSA was in the range of 0.01 to 5 mg/ml during the layer absorption. It was found that the BSA adsorption strongly depends on the pH of solution, and the concentration of BSA. The absorption layer occurred maximum at the pH value of 3.5 which resulted from the charge of PSMA and BSA molecules. The layer formation reached the saturate value at the concentration higher than 3 mg/ml. The molecular packing of the BSA layer at different pH values was determined by AFM and total mass change of QCM.

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