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]

scholarly journals Investigation of the morphology and surface properties of crosslinked poly(urethane-ester-siloxane)s

2012 ◽  
Vol 66 (6) ◽  
pp. 813-821 ◽  
Author(s):  
Jasna Dzunuzovic ◽  
Marija Pergal ◽  
Vesna Vodnik ◽  
Milena Spírková ◽  
Rafał Poręba ◽  
...  
Keyword(s):  
Ethylene Oxide ◽  
Water Absorption ◽  
Surface Properties ◽  
Microphase Separation ◽  
Crosslinking Agent ◽  
Hydrophobic Surface ◽  
Sem Analysis ◽  
Force Microscopy ◽  
Hyperbranched Polyesters ◽  
Atomic Force

Two series of crosslinked poly(urethane-ester-siloxane)s were synthesized from ?,?-dihydroxy-(ethylene oxide-poly(dimethylsiloxane)-ethylene oxide) (EO-PDMS-EO), 4,4?-methylenediphenyl diisocyanate and Boltorn? hyperbranched polyesters of the second and third pseudo generation, by a two-step polymerization in solution. The effect of the EO-PDMS-EO content and functionality of the applied crosslinking agent on the morphology and surface properties of the prepared poly(urethane-ester-siloxane)s was investigated by FTIR spectroscopy, small-angle X-ray scattering (SAXS), atomic force microscopy (AFM), scanning electron microscopy (SEM) and water absorption measurement. Different techniques (FTIR peak deconvolution, SAXS and AFM) revealed that decrease of the crosslinking agent functionality and EO-PDMS-EO content promotes microphase separation in the synthesized poly(urethane-ester-siloxane)s. SEM analysis and water absorption experiments showed that due to the hydrophobic character of EO-PDMS-EO and its ability to migrate to the surface of poly(urethane-ester-siloxane)s, samples synthesized with higher EO-PDMS-EO content and crosslinking agent of lower functionality have more hydrophobic surface and better waterproof performances. The obtained results indicate that the synthesis of poly(urethane-ester-siloxane)s based on EO-PDMS-EO and Boltorn? hyperbranched polyesters leads to the creation of networks with interesting morphological and surface properties, which can be easily tailored by changing the content of EO-PDMS-EO segment or functionality of hyperbranched polyester.

scholarly journals Influence of Polyol/Crosslinker Blend Composition on Phase Separation and Thermo-Mechanical Properties of Polyurethane Thin Films

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 666 ◽  
Author(s):  
Said Arévalo-Alquichire ◽  
Maria Morales-Gonzalez ◽  
Kelly Navas-Gómez ◽  
Luis E. Diaz ◽  
José A. Gómez-Tejedor ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Phase Separation ◽  
Loss Factor ◽  
Microphase Separation ◽  
Mechanical Analysis ◽  
Damping Capacity ◽  
Force Microscopy ◽  
X Ray Scattering ◽  
Atomic Force ◽  
Hard Segments

Polyurethanes (PUs) from Polyethylene glycol (PEG) and polycaprolactone diol (PCL) and a crosslinker, Pentaerythritol (PE), were synthetized with isophorone diisocyanate (IPDI). In this study, we investigated the effect of polyol and crosslinker composition on phase separation and thermo-mechanical properties. The properties were studied through dynamic mechanical analysis, X-ray scattering, atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The results showed changes in PUs properties, microphase structure, and separation due to the composition of polyol/crosslinker blend. So, the largest concentration of PE produced multimodal loss factor patterns, indicating segment segregation while PUs with a PEG/PCL = 1 displayed a monomodal loss factor pattern, indicating a homogeneously distributed microphase separation. Additionally, the increase of the PEG concentration enhanced the damping capacity. On the other hand, agglomeration and thread-like structures of hard segments (HS) were observed through AFM. Finally, the thermal behavior of PUs was affected by chemical composition. Lower concentration of PE reduced the crosslinking; hence, the temperature with the maximum degradation rate.

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).

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.

scholarly journals Synthesis of amphiphilic ABA triblock oligomer via ATRP and its surface properties

2017 ◽  
Vol 95 (5) ◽  
pp. 605-611 ◽  
Author(s):  
Lei Wang ◽  
Shaoqing Wen ◽  
Zhanxiong Li
Keyword(s):  
Photoelectron Spectroscopy ◽  
Microphase Separation ◽  
Gel Permeation Chromatography ◽  
Contact Angles ◽  
Chemical Compositions ◽  
Water Contact ◽  
Force Microscopy ◽  
Atomic Force ◽  
Poly Ethylene ◽  
Magnetic Resonances

A series of novel amphiphilic ABA-type poly(tridecafluorooctylacrylate)-poly(ethylene glycol)-poly(tridecafluorooctylacrylate) (henceforth referred to as p-TDFA-PEG-p-TDFA) triblock oligomers were successfully synthesized via atom transfer radical polymerization (ATRP) using well-defined Br-PEG-Br as macroinitiator and copper as catalyst. The block oligomers were characterized by Fourier transform infrared (FTIR) spectroscopy and 1H and 19F nuclear magnetic resonances (NMR). Gel permeation chromatography (GPC) showed that the block oligomers have been obtained with narrow molecular weight distributions of 1.22–1.33. X-ray photoelectron spectroscopy (XPS) was carried out to confirm the attachment of p-TDFA-PEG-p-TDFA onto the silicon substrate, together with the chemical compositions of p-TDFA-PEG-p-TDFA. The wetabilities of the oligomer films were measured by water contact angles (CAs). Water CAs of p-TDFA-PEG-p-TDFA film were measured and their morphologies were tested by atomic force microscopy (AFM). The result showed that the CAs of the oligomer films, which possess fluoroalkyl groups assembled on the outer surface, increase after heating due to the migration of fluoroalkyl groups and the resulted microphase separation of the p-TDFA-PEG-p-TDFA.

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.

scholarly journals Coupling the Microscopic Healing Behaviour of Coatings to the Thermoreversible Diels-Alder Network Formation

Coatings ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 13 ◽  
Author(s):  
Joost Brancart ◽  
Robrecht Verhelle ◽  
Jessica Mangialetto ◽  
Guy Van Assche
Keyword(s):  
Network Formation ◽  
Polymer Network ◽  
Cycloaddition Reaction ◽  
Thermomechanical Properties ◽  
Alder Reaction ◽  
Diels Alder ◽  
Force Microscopy ◽  
Diels Alder Reaction ◽  
Atomic Force ◽  
Microscopic Evaluation

While thermally reversible polymer network coatings based on the Diels-Alder reaction are widely studied, the mechanisms responsible for the heating-mediated healing of damage is still not well understood. The combination of microscopic evaluation techniques and fundamental insights for the thermoreversible network formation in the bulk and coating shed light on the mechanisms behind the damage healing events. The thermomechanical properties of thermoset and elastomer coatings, crosslinked by the furan-maleimide Diels-Alder cycloaddition reaction, were studied in bulk and compared to the thermal behaviour applied as coatings onto aluminium substrates. The damage sealing of thermoset (Tg = 79 °C) and elastomer (Tg = −49 °C) coatings were studied using nano-lithography and atomic force microscopy (AFM). The sealing event is studied and modelled at multiple temperatures and correlated to the changes in the network structure and corresponding thermomechanical properties.

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