Phase separation in urethane elastomers as judged by low-angle X-ray scattering. I. Fundamentals

Bonart, R.; Müller, E. H.

doi:10.1080/00222347408219403

Cited by 167 publications

(64 citation statements)

References 13 publications

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“…The observation that the UTS of E2A decreased after high temperature aging in PBS is consistent with several previous studies of other thermoplastic polyurethanes (TPUs). 20,30,33,[37][38][39] In these studies, a variety of polyether polyurethanes were aged in aqueous solution between 80 and 100 C for periods of between 16 and 40 weeks. As shown in Figure 9, all of these studies demonstrated a decrease in the UTS of TPUs aged in aqueous solution at high temperatures.…”

Section: Discussionmentioning

confidence: 99%

“…30 Thus, the saturation level, M sat , depends on temperature as follows: M sat 5 M ðsat ;0Þ exp 2 DH s =RT ð Þ , where M (sat,0) is a constant, DH s is the enthalpy of mixing, R is the gas constant (R 5 8.32 3 10 23 kg mol 21 K 21 ), and T is the temperature in Kelvin. 33 In the current study, water saturation levels (M sat ) increased consistently with temperature for all materials, following an Arrhenius relationship.…”

Section: Water Absorption Testingmentioning

confidence: 99%

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Limitations of predictingin vivobiostability of multiphase polyurethane elastomers using temperature-accelerated degradation testing

Padsalgikar

Cosgriff‐Hernandez

Gallagher

et al. 2014

J. Biomed. Mater. Res.

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Polyurethane biostability has been the subject of intense research since the failure of polyether polyurethane pacemaker leads in the 1980s. Accelerated in vitro testing has been used to isolate degradation mechanisms and predict clinical performance of biomaterials. However, validation that in vitro methods reproduce in vivo degradation is critical to the selection of appropriate tests. High temperature has been proposed as a method to accelerate degradation. However, correlation of such data to in vivo performance is poor for polyurethanes due to the impact of temperature on microstructure. In this study, we characterize the lack of correlation between hydrolytic degradation predicted using a high temperature aging model of a polydimethylsiloxane-based polyurethane and its in vivo performance. Most notably, the predicted molecular weight and tensile property changes from the accelerated aging study did not correlate with clinical explants subjected to human biological stresses in real time through 5 years. Further, DMTA, ATR-FTIR, and SAXS experiments on samples aged for 2 weeks in PBS indicated greater phase separation in samples aged at 85°C compared to those aged at 37°C and unaged controls. These results confirm that microstructural changes occur at high temperatures that do not occur at in vivo temperatures. In addition, water absorption studies demonstrated that water saturation levels increased significantly with temperature. This study highlights that the multiphase morphology of polyurethane precludes the use of temperature accelerated biodegradation for the prediction of clinical performance and provides critical information in designing appropriate in vitro tests for this class of materials.

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Section: Discussionmentioning

confidence: 99%

Section: Water Absorption Testingmentioning

confidence: 99%

Limitations of predictingin vivobiostability of multiphase polyurethane elastomers using temperature-accelerated degradation testing

Padsalgikar

Cosgriff‐Hernandez

Gallagher

et al. 2014

J. Biomed. Mater. Res.

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“…It is well established that segmented copolymers can undergo microphase separation into soft and hard domains giving rise to hierarchically ordered structures that display a wide range of morphologies [25][26][27]. This type of self organization is thermodynamically driven (unfavorable enthalpic contribution of intersegmental mixing) with hydrogen bonding diminishing (hard-hard bridging) or even enhancing (hard-soft bridging) the compatibility of the two phases.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Fouling release nanostructured coatings based on PDMS-polyurea segmented copolymers

Fang

Kelarakis

Wang

et al. 2010

Polymer

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The bulk and surface characteristics of a series of coatings based on PDMS-polyurea segmented copolymers were correlated to their fouling release performance. Incorporation of polyurea segments to PDMS backbone gives rise to phase separation with the extensively hydrogen bonded hard domains creating an interconnected network that imparts mechanical rigidity.Increasing the compositional complexity of the system by including fluorinated or POSS functionalized chain extenders or through nanoclay intercalation, confers further thermomechanical improvements. In analogy to the bulk morphology, the surface topography also reflects the compositional complexity of the materials, displaying a wide range of motifs.Investigations on settlement and subsequent removal of Ulva sporelings on those nanostructured surfaces indicate that the work required to remove the microorganisms is significantly lower compared to coatings based on standard PDMS homopolymer. All in all, the series of materials considered in this study demonstrate advanced fouling release properties, while exhibiting superior mechanical properties and, thus, long term durability.

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“…Microphase separation in IPNs may be characterized by the so-called segregation degree. This conventional parameter was introduced by Bonart and Muller [42] and characterizes the fraction of the two-phase system which is separated into phases of pure components whereas the rest of material stays fully unseparated. Segregation degree may be found from the SAXS data and from the measurements of viscoelastic characteristics.…”

Section: Dependence Of the Onset Of Microphase Separation On Reactionmentioning

confidence: 99%

Interpenetrating Polymer Networks Based on Polyurethane and Poly(butyl methacrylate): Interrelation Between Reaction Kinetics and Microphase Structure

Lipatov

Alekseeva

1996

Polym. Adv. Technol.

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The effect of the reaction kinetics on the formation of semi‐IPNs based on crosslinked polyurethane and linear poly(butyl methacrylate) of various compositions has been studied. New data are presented concerning the interconnection between the reaction kinetics, gelation and rheokinetics of IPN formation, between kinetics and crosslinking density, microphase structure and degree of microphase separation. It was shown that kinetic factors determine the conditions of microphase separation and formation of microphase structure.

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Phase separation in urethane elastomers as judged by low-angle X-ray scattering. I. Fundamentals

Cited by 167 publications

References 13 publications

Limitations of predictingin vivobiostability of multiphase polyurethane elastomers using temperature-accelerated degradation testing

Limitations of predictingin vivobiostability of multiphase polyurethane elastomers using temperature-accelerated degradation testing

Fouling release nanostructured coatings based on PDMS-polyurea segmented copolymers

Interpenetrating Polymer Networks Based on Polyurethane and Poly(butyl methacrylate): Interrelation Between Reaction Kinetics and Microphase Structure

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