scholarly journals Effect of Domain Structure of Segmented Poly(urethane-imide) Membranes with Polycaprolactone Soft Blocks on Dehydration of n-Propanol via Pervaporation

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1222 ◽  
Author(s):  
Maria Sokolova ◽  
Alexander Bugrov ◽  
Michael Smirnov ◽  
Alexander Smirnov ◽  
Erkki Lahderanta ◽  
...  
Keyword(s):  
Transport Properties ◽  
Soft Segment ◽  
Chain Extension ◽  
Soft Matrix ◽  
Force Microscopy ◽  
Molecular Weights ◽  
X Ray Scattering ◽  
Atomic Force ◽  
Structure Morphology ◽  
Soft Segments

Segmented poly(urethane-imide)s (PUIs) were synthesized by polyaddition reaction and applied for preparation of membranes. Tolylene-2,4-diisocyanate, pyromellitic dianhydride, and m-phenylenediamine for chain extension were used to form hard aromatic blocks. Polycaprolactone diols with molecular weights equal to 530 and 2000 g mol−1 were chosen as soft segments. The effect of the length of soft segments on the structure, morphology, and transport properties of segmented poly(urethane-imide) membranes were studied using atomic force microscopy, small-angle and wide-angle X-ray scattering, and pervaporation experiments. It was found that a copolymer with a shorter soft segment (530 g mol−1) consists of soft domains in a hard matrix, while the introduction of polycaprolactone blocks with higher molecular weight (2000 g mol−1) leads to the formation of hard domains in a soft matrix. Additionally, the introduction of hard segments prevents crystallization of polycaprolactone. Transport properties of membranes based on segmented PUIs containing soft segments of different length were tested for pervaporation of a model mixture of propanol/water with 20 wt % H2O content. It was found that a membrane based on segmented PUIs containing longer soft segments demonstrates higher flux (8.8 kg μm m−2 h−1) and selectivity (179) toward water in comparison with results for pure polycaprolactone reported in literature. The membrane based on segmented PUIs with 530 g mol−1 soft segment has a lower flux (5.1 kg μm m−2 h−1) and higher selectivity (437).

scholarly journals Study on the morphology and thermomechanical properties of poly(urethane-siloxane) networks based on hyperbranched polyester

2013 ◽  
Vol 67 (6) ◽  
pp. 871-879
Author(s):  
Marija Pergal ◽  
Jasna Dzunuzovic ◽  
Milena Spírková ◽  
Rafal Poręba ◽  
Milos Steinhart ◽  
...  
Keyword(s):  
Ethylene Oxide ◽  
Microphase Separation ◽  
Soft Segment ◽  
Hydrophobic Surface ◽  
Crosslinking Density ◽  
Thermomechanical Properties ◽  
Hyperbranched Polyester ◽  
Force Microscopy ◽  
X Ray Scattering ◽  
Atomic Force

Two series of polyurethane films based on hyperbranched polyester of the second pseudogeneration (Boltorn?), 4,4'-methylenediphenyl diisocyanate and two different siloxane prepolymers, ?,?-dihydroxy-(ethylene oxide-poly(dimethylsiloxane)-ethylene oxide) (EO-PDMS-EO) and ?,?-dihydroxypropyl-poly(dimethylsiloxane) (HP-PDMS), were prepared by two-step polymerization in solution. The influence of the type and content of soft segment on the morphology, thermomechanical and surface properties of the synthesized polyurethanes was studied by atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM), dynamic mechanical thermal analysis (DMTA) and water absorption measurements. It was found that these techniques confirmed existence of microphase separated morphology. Synthesized polyurethanes exhibited two glass transition temperatures and one second relaxation process. The results showed that polyurethanes based on HP-PDMS had higher surface roughness, better microphase separation and waterproof performances. Samples synthesized with lower PDMS content had less hydrophobic surface, but higher crosslinking density and better thermomechanical properties. (Projekat Ministarstva nauke Republike Srbije, br. 172062]

In situ X-ray Scattering Study of the Formation of Au Nano Crystals During Thermal Annealing

2007 ◽  
Vol 1027 ◽  
Author(s):  
Do Young Noh ◽  
Ki-Hyun Ryu ◽  
Hyon Chol Kang
Keyword(s):  
Thermal Annealing ◽  
Bragg Reflection ◽  
Ex Situ ◽  
X Ray ◽  
Force Microscopy ◽  
X Ray Scattering ◽  
Atomic Force ◽  
Au Thin Films ◽  
Ray Scattering

AbstractThe transformation of Au thin films grown on sapphire (0001) substrates into nano crystals during thermal annealing was investigated by in situ synchrotron x-ray scattering and ex situ atomic force microscopy (AFM). By monitoring the Au(111) Bragg reflection and the low Q reflectivity and comparing them with ex situ AFM images, we found that polygonal-shape holes were nucleated and grow initially. As the holes grow larger and contact each other, their boundary turns into Au nano crystals. The Au nano crystals have a well-defined (111) flat top surface and facets in the in-plane direction.

Effect of Catalysts on the Properties of Fluorinated Polyurethanes

2013 ◽  
Vol 464 ◽  
pp. 9-13 ◽  
Author(s):  
Zan Li ◽  
Xia Wang ◽  
Ying Li ◽  
Wei Chain ◽  
Jiao Jiao Hu
Keyword(s):  
Hard Segment ◽  
Soft Segment ◽  
Force Microscopy ◽  
Atomic Force ◽  
Structure Surface ◽  
Improved Stability ◽  
Ft Ir ◽  
Tin Metal ◽  
Polyether Polyol ◽  
Catalyst Efficiency

Fluorinated polyurethanes (FPU) was prepared using fluorinated polyether polyol (FPO) as the soft segment, 4,4`-diphenylmethane diisocyanate (MDI) as the hard segment, 1,4-butanodiol (BDO) as the chain extender and catalysts. Tin metal catalysts were used to catalyze the polyurethane reaction of polyether polyols and isocyanate. The effect of different catalysts including stannous octoate (T-9) and dibutyltindalautrate (DBTDL) on the structure, surface properties and thermal properties of FPU was studied. The structural elucidation of the synthesized FPU was performed by Fourier transform infrared (FT-IR) and discovered that with decreasing catalyst efficiency or without catalyst, the strength of hydrogen bounds were enhanced. The FPU films surface was characterized by contact angle (CA) and atomic force microscopy (AFM) and it was found that the phase separation was increasing with increasing catalyst efficiency. The thermal property was exhibited by Thermo gravimetric (TG) and showed that joining catalyst improved stability significantly.

Coupling In-Situ Techniques to Analyze Zinc Deposition and Dissolution for Energy Storage Applications

2013 ◽  
Vol 1491 ◽  
Author(s):  
Jayme Keist ◽  
Christine Orme ◽  
Frances Ross ◽  
Dan Steingart ◽  
Paul Wright ◽  
...  
Keyword(s):  
Liquid Electrolyte ◽  
Scattering Data ◽  
Zinc Deposition ◽  
Ionic Liquid Electrolyte ◽  
Force Microscopy ◽  
In Situ Techniques ◽  
X Ray Scattering ◽  
Atomic Force ◽  
Afm Analysis

ABSTRACTThis investigation describes preliminary results of in-situ analysis of zinc deposition within an ionic liquid electrolyte utilizing electrochemical atomic force microscopy (EC AFM). From the AFM analysis, the morphology of the zinc deposition was analyzed by quantifying the surface roughness using height-height correlation functions. These results will be used to analyze the scattering data obtained from zinc deposition analysis utilizing an electrochemical ultra-small angle x-ray scattering (EC USAXS). The goal of this research is to link the early nucleation and growth behavior to the formation of detrimental morphologies.

Intrinsic roughness and interfaces of Cr/Be multilayers

2021 ◽  
Vol 54 (6) ◽  
Author(s):  
Roman Pleshkov ◽  
Nikolay Chkhalo ◽  
Vladimir Polkovnikov ◽  
Mikhail Svechnikov ◽  
Maria Zorina
Keyword(s):  
Atomic Force Microscopy ◽  
Optical Contrast ◽  
Multilayer Mirrors ◽  
X Ray ◽  
Force Microscopy ◽  
Layer Material ◽  
Multilayer Mirror ◽  
X Ray Scattering ◽  
Atomic Force ◽  
Sharp Structure

The structures of Cr/Be multilayer mirror interfaces are investigated using X-ray reflectometry, diffuse X-ray scattering and atomic force microscopy. The combination of these methods makes it possible to separate the contributions of roughness and interlayer diffusion/intermixing for each sample. In the range of period thicknesses of 2.26–0.8 nm, it is found that the growth roughness of the Cr/Be multilayer mirrors does not depend on the period thickness and is ∼0.2 nm. The separation of roughness and diffuseness allows estimation of layer material intermixing and the resulting drop in the optical contrast, which is from 0.85 to 0.17 in comparison with an ideally sharp structure.

Dynamic Debonding Force Measurements of Ligand (RGD)-Platelet Receptor (GP Ilb/IIIa) System under Physiological Conditions

2000 ◽  
Vol 6 (S2) ◽  
pp. 974-975
Author(s):  
ImShik Lee ◽  
Roger E. Marchant
Keyword(s):  
Thrombus Formation ◽  
Peptide Sequence ◽  
Chain Extension ◽  
Force Measurements ◽  
Platelet Surface ◽  
Force Microscopy ◽  
Atomic Force ◽  
Direct Measurements ◽  
Platelet Receptor ◽  
Physical Absorption

ABSTRACTBinding formation between a peptide sequence (GSSSGRGDSPA) which contains the cell adhesion sequence –RGD-found in fibrinogen, vWF, fibrinonectin, and vitronectin and human platelet intergrin GP Ilb/IIIa plays an important role in thrombus formation. Using atomic force microscopy (AFM), we visualized the detailed structures of membrane and submembrane of the cell, and measured the interaction forces between a peptide modified cantilever probe tip and platelet surface from pN to nN levels under physiological buffer. Direct measurements of the debonding force for the RGD ligand - GP Ilb/IIIa system are presented. To eliminate the possible measurement of the hgand-receptor pair, or of the ligand and AFM tip, following desorption of the ligand; the cantilever tip surface was modified with covalent coupling chemistry rather than physical absorption. Our results showed that the single molecular rupturing force was 93.3 ± 10.41 pN with considerable chain extension in the receptor. The rupturing forces showed a logarithmic dependence of the rate of loading

Comparative study of the roughness of optical surfaces and thin films by use of x-ray scattering and atomic force microscopy

1999 ◽  
Vol 38 (4) ◽  
pp. 684 ◽  
Author(s):  
Victor E. Asadchikov ◽  
Angela Duparré ◽  
Stefan Jakobs ◽  
Albert Yu. Karabekov ◽  
Igor V. Kozhevnikov ◽  
...  
Keyword(s):  
Thin Films ◽  
Atomic Force Microscopy ◽  
Comparative Study ◽  
X Ray ◽  
Force Microscopy ◽  
Optical Surfaces ◽  
X Ray Scattering ◽  
Atomic Force ◽  
Ray Scattering

Microstructural Characterization of Polyanhydride Blends for Controlled Drug Delivery

2000 ◽  
Vol 662 ◽  
Author(s):  
Elizabeth E. Shen ◽  
Hsin-Lung Chen ◽  
Balaji Narasimhan
Keyword(s):  
Drug Delivery ◽  
Microstructural Characterization ◽  
Peak Shift ◽  
Crystalline Morphology ◽  
X Ray ◽  
Force Microscopy ◽  
X Ray Scattering ◽  
Atomic Force ◽  
Drug Delivery Devices

AbstractThis research examines the microstructure of polyanhydride blends for use in drug delivery devices. Atomic force microscopy (AFM) and small-angle X-ray scattering (SAXS) studies were performed on the homopolymers and blends of the polyanhydrides poly(1,6-carboxyphenoxy hexane) (CPH) and poly(sebacic anhydride) (SA). AFM of the CPH/SA blends 20:80, 50:50, and 80:20 showed distinct patterns indicating spinodal decomposition and phase separation on the micron-scale. Because it has been shown that incorporated drugs will thermodynamically partition into phase-separated domains depending on their hydrophobicity, polyanhydride blends will be able to encapsulate larger bioactive compounds including nucleotides, proteins, and vaccines. Preliminary SAXS studies of the CPH/SA blend systems provide information on the crystalline morphology of the polymer. A peak shift to a lower q from poly(SA) to the blends indicates that the poly(CPH) is incorporated into and causes swelling of the interlamellar amorphous regions of poly(SA).

When dendrimers are not better – rational design of nanolayers for high-performance organic electronic devices

Nanoscale ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 4463-4470 ◽  
Author(s):  
Maxim A. Shcherbina ◽  
Oleg V. Borshchev ◽  
Alexandra P. Pleshkova ◽  
Sergei A. Ponomarenko ◽  
Sergei N. Chvalun
Keyword(s):  
High Performance ◽  
Rational Design ◽  
Electronic Devices ◽  
Carbosilane Dendrimers ◽  
Scanning Calorimetry ◽  
Organic Electronic Devices ◽  
X Ray ◽  
Force Microscopy ◽  
X Ray Scattering ◽  
Atomic Force

Several generations of carbosilane dendrimers with quaterthiophene end groups were studied by X-ray scattering, differential scanning calorimetry, polarizing optical and atomic force microscopy and molecular modelling.

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