scholarly journals Hybrid Complex Coacervate

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 320 ◽  
Author(s):  
Marco Dompé ◽  
Francisco Javier Cedano-Serrano ◽  
Mehdi Vahdati ◽  
Dominique Hourdet ◽  
Jasper van der Gucht ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Ionic Strength ◽  
Solution Temperature ◽  
Moderate Increase ◽  
Adhesive Properties ◽  
Underwater Adhesion ◽  
Complex Coacervate ◽  
Hybrid Complex ◽  
Strength Gradient ◽  
Oppositely Charged

Underwater adhesion represents a huge technological challenge as the presence of water compromises the performance of most commercially available adhesives. Inspired by natural organisms, we have designed an adhesive based on complex coacervation, a liquid–liquid phase separation phenomenon. A complex coacervate adhesive is formed by mixing oppositely charged polyelectrolytes bearing pendant thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) chains. The material fully sets underwater due to a change in the environmental conditions, namely temperature and ionic strength. In this work, we incorporate silica nanoparticles forming a hybrid complex coacervate and investigate the resulting mechanical properties. An enhancement of the mechanical properties is observed below the PNIPAM lower critical solution temperature (LCST): this is due to the formation of PNIPAM–silica junctions, which, after setting, contribute to a moderate increase in the moduli and in the adhesive properties only when applying an ionic strength gradient. By contrast, when raising the temperature above the LCST, the mechanical properties are dominated by the association of PNIPAM chains and the nanofiller incorporation leads to an increased heterogeneity with the formation of fracture planes at the interface between areas of different concentrations of nanoparticles, promoting earlier failure of the network—an unexpected and noteworthy consequence of this hybrid system.

scholarly journals Tuning the Interactions in Multiresponsive Complex Coacervate-Based Underwater Adhesives

2019 ◽  
Vol 21 (1) ◽  
pp. 100 ◽  
Author(s):  
Marco Dompé ◽  
Francisco J. Cedano-Serrano ◽  
Mehdi Vahdati ◽  
Ugo Sidoli ◽  
Olaf Heckert ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Adhesive System ◽  
Systematic Investigation ◽  
High Ionic Strength ◽  
Work Of Adhesion ◽  
Polymer Composition ◽  
Adhesive Properties ◽  
Preparation Conditions ◽  
Complex Coacervate ◽  
Non Covalent Interactions

In this work, we report the systematic investigation of a multiresponsive complex coacervate-based underwater adhesive, obtained by combining polyelectrolyte domains and thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) units. This material exhibits a transition from liquid to solid but, differently from most reactive glues, is completely held together by non-covalent interactions, i.e., electrostatic and hydrophobic. Because the solidification results in a kinetically trapped morphology, the final mechanical properties strongly depend on the preparation conditions and on the surrounding environment. A systematic study is performed to assess the effect of ionic strength and of PNIPAM content on the thermal, rheological and adhesive properties. This study enables the optimization of polymer composition and environmental conditions for this underwater adhesive system. The best performance with a work of adhesion of 6.5 J/m2 was found for the complex coacervates prepared at high ionic strength (0.75 M NaCl) and at an optimal PNIPAM content around 30% mol/mol. The high ionic strength enables injectability, while the hydrated PNIPAM domains provide additional dissipation, without softening the material so much that it becomes too weak to resist detaching stress.

scholarly journals Complexation and coacervation of like-charged polyelectrolytes inspired by mussels

2016 ◽  
Vol 113 (7) ◽  
pp. E847-E853 ◽  
Author(s):  
Sangsik Kim ◽  
Jun Huang ◽  
Yongjin Lee ◽  
Sandipan Dutta ◽  
Hee Young Yoo ◽  
...  
Keyword(s):  
Electrostatic Interactions ◽  
Short Range ◽  
Self Healing ◽  
New Paradigm ◽  
Polyelectrolyte Complexes ◽  
Underwater Adhesion ◽  
Complex Coacervate ◽  
Low Interfacial Tension ◽  
Oppositely Charged ◽  
Positively Charged

It is well known that polyelectrolyte complexes and coacervates can form on mixing oppositely charged polyelectrolytes in aqueous solutions, due to mainly electrostatic attraction between the oppositely charged polymers. Here, we report the first (to the best of our knowledge) complexation and coacervation of two positively charged polyelectrolytes, which provides a new paradigm for engineering strong, self-healing interactions between polyelectrolytes underwater and a new marine mussel-inspired underwater adhesion mechanism. Unlike the conventional complex coacervate, the like-charged coacervate is aggregated by strong short-range cation–π interactions by overcoming repulsive electrostatic interactions. The resultant phase of the like-charged coacervate comprises a thin and fragile polyelectrolyte framework and round and regular pores, implying a strong electrostatic correlation among the polyelectrolyte frameworks. The like-charged coacervate possesses a very low interfacial tension, which enables this highly positively charged coacervate to be applied to capture, carry, or encapsulate anionic biomolecules and particles with a broad range of applications.

scholarly journals Effects of Different Solid Solution Temperatures on Microstructure and Mechanical Properties of the AA7075 Alloy After T6 Heat Treatment

2019 ◽  
Vol 38 (2019) ◽  
pp. 892-896 ◽  
Author(s):  
Süleyman Tekeli ◽  
Ijlal Simsek ◽  
Dogan Simsek ◽  
Dursun Ozyurek
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Solid Solution ◽  
Tensile Strength ◽  
Tensile Tests ◽  
Solution Temperature ◽  
T6 Heat Treatment ◽  
Microstructure And Mechanical Properties ◽  
Different Temperatures

AbstractIn this study, the effect of solid solution temperature on microstructure and mechanical properties of the AA7075 alloy after T6 heat treatment was investigated. Following solid solution at five different temperatures for 2 hours, the AA7075 alloy was quenched and then artificially aged at 120∘C for 24 hours. Hardness measurements, microstructure examinations (SEM+EDS, XRD) and tensile tests were carried out for the alloys. The results showed that the increased solid solution temperature led to formation of precipitates in the microstructures and thus caused higher hardness and tensile strength.

Mechanical Properties of Epoxy Adhesive Under Thermal Aging and Their Chemical Degradation Behavior

2021 ◽  
Vol 21 (8) ◽  
pp. 4444-4449
Author(s):  
Bongjin Chung ◽  
Shin Sungchul ◽  
Jaeho Shim ◽  
Seongwoo Ryu
Keyword(s):  
Mechanical Properties ◽  
Thermal Aging ◽  
Photoelectron Spectroscopy ◽  
Thermal Exposure ◽  
Chain Scission ◽  
Epoxy Adhesive ◽  
Chemical Degradation ◽  
Adhesive Properties ◽  
Noticeable Reduction

Epoxy adhesive was analyzed under long term thermal aging and mechanical properties and chemical degradation were observed by X-ray photoelectron spectroscopy (XPS). Long term thermal exposure of epoxy causes a noticeable reduction in adhesive properties. We developed a predictive model of temperature and time dependent aging. The temperature dependent aging behavior of epoxy adhesive shows good agreement with conventional Arrhenius equations. Using XPS analysis, we also discovered a correlation between chemical degradation and the adhesive properties. Decay of C–C bonding ratio induced chain-scission of epoxy adhesive; increase of total numbers of C–O and C═O induced oxidation of epoxy adhesive during thermal exposure.

scholarly journals The Effect of Heat Treatment on the Microstructure and Mechanical Properties of the Novel Low-Cost Ti-3Al-5Mo-4Cr-2Zr-1Fe Alloy

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3798
Author(s):  
Meng Sun ◽  
Dong Li ◽  
Yanhua Guo ◽  
Ying Wang ◽  
Yuecheng Dong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aging Time ◽  
Volume Fraction ◽  
Low Cost ◽  
Solution Treatment ◽  
Solution Temperature ◽  
The Novel ◽  
Α Phase ◽  
The Cost

In order to reduce the cost of titanium alloys, a novel low-cost Ti-3Al-5Mo-4Cr-2Zr-1Fe (Ti-35421) titanium alloy was developed. The influence of heat treatment on the microstructure characteristics and mechanical properties of the new alloy was investigated. The results showed that the microstructure of Ti-35421 alloy consists of a lamina primary α phase and a β phase after the solution treatment at the α + β region. After aging treatment, the secondary α phase precipitates in the β matrix. The precipitation of the secondary α phase is closely related to heat treatment parameters—the volume fraction and size of the secondary α phase increase when increasing the solution temperature or aging time. At the same solution temperature and aging time, the secondary α phase became coarser, and the fraction decreased with increasing aging temperature. When Ti-35421 alloy was solution-treated at the α + β region for 1 h with aging surpassing 8 h, the tensile strength, yield strength, elongation and reduction of the area were achieved in a range of 1172.7–1459.0 MPa, 1135.1–1355.5 MPa, 5.2–11.8%, and 7.5–32.5%, respectively. The novel low-cost Ti-35421 alloy maintains mechanical properties and reduces the cost of materials compared with Ti-3Al-5Mo-5V-4Cr-2Zr (Ti-B19) alloy.

Development of breathable Janus superhydrophobic polyester fabrics using alkaline hydrolysis and blade coating

2018 ◽  
Vol 89 (6) ◽  
pp. 959-974 ◽  
Author(s):  
Seonyoung Youn ◽  
Chung Hee Park
Keyword(s):  
Mechanical Properties ◽  
Alkaline Hydrolysis ◽  
Structural Changes ◽  
Treatment Time ◽  
Volume Ratio ◽  
Alkaline Treatment ◽  
The Other ◽  
Solution Temperature ◽  
Optimal Conditions ◽  
Wetting Properties

Alkaline hydrolysis is a common finishing method that is used to give polyester (polyethylene terephthalate, PET) a more natural touch and improved luster via chemical or physical changes in the fibers. However, its potential as a tool for surface modification in the development of single-sided superhydrophobic materials has not been studied yet. In this research, Janus superhydrophobic PET fabrics with asymmetric wetting properties (one side of the PET surface was rendered superhydrophobic while the other side was simply hydrophobic) were fabricated in two steps. Fine roughness was first achieved on the surface of PET fabrics by alkaline hydrolysis. Subsequently, optimized foam-coating emulsions were applied on only one surface of the alkaline-hydrolyzed PET. Alkaline treatment time, solution temperature, and viscosity of the foam-coating emulsions were varied to find optimal conditions in terms of structural changes, mechanical properties, superhydrophobicity, and absorption ability. The specimen treated with an aqueous solution of 8% sodium hydroxide at 70℃ for 60 min and coated with the mixture of the fluoro-emulsion and thickener in the volume ratio of 40:2 was determined to be the optimal conditions for the Janus superhydrophobic property. This sample showed a contact angle of 162.8° and a shedding angle of 5.6° on one side, whereas it completely permitted the percolation of water drops on the other side within 109 s. The mechanical properties of the developed Janus PET under the optimal conditions did not decrease significantly; its weight and tensile strength were found to have decreased by 3.3% and 19.2%, respectively. Furthermore, the single-sided superhydrophobic specimen demonstrated higher moisture transmissibility than the double-sided coated PET under the same alkaline treatment conditions. The method developed herein eliminates the requirement for an additional process to deliver nanoscale surface roughness and has the potential to produce waterproof–breathable PET fabrics for outdoor clothing.

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