Phase-Separation-Induced Anomalous Stiffening, Toughening, and Self-Healing of Polyacrylamide Gels

Graphene oxide microcapsules (GOMs) have been prepared through Pickering emulsion method by varying the disperse speed to study its effect on the GOM’s size. The GOMs were characterized through phase separation observation, polarized optical microscope (POM), and particle size analyser (PSA). Phase separation observation showed more viscous and cloudy emulsion was produced when the disperse speed was increased. After 24 hours, only 800 rpm emulsion did not show any phase separation. POM characterization depicted that increasing the emulsification energy led to the finer emulsion with the 1200 rpm sample showing the smallest microcapsule size of around 8 ?m. However, PSA analysis suggested that although the disperse speed controls the GOMs size, the amount of GO in the emulsion plays an important role for the microcapsule to maintain its stability. Emulsion produced at 800 rpm possesses satisfactory stability with GOMs diameter of 11.15 ?m. The result also suggested that graphene oxide encapsulated linseed oil may act as a promising candidate for healing microcapsules in a self-healing coating system. ABSTRAK: Mikrokapsul graphene oksida (GOMs) telah dihasilkan melalui kaedah emulsifikasi Pickering dengan memvariasikan tenaga pengemulsi untuk mengkaji kesannya terhadap saiz GOMs. GOMs dicirikan melalui pemerhatian pemisahan fasa, mikroskop optik polarisasi (POM) dan penganalisis saiz zarah (PSA). Pemerhatian pemisahan fasa menunjukkan emulsi yang lebih likat dan keruh dihasilkan apabila kelajuan pengemulsi meningkat. Selepas 24 jam, hanya emulsi 800 rpm tidak menunjukkan pemisahan fasa. Pencirian POM meunjukkan bahawa peningkatan tenaga pengemulsi menghasilkan emulsi yang lebih halus dengan sampel 1200 rpm menunjukkan saiz mikrokapsul terkecil, sekitar 8 ?m. Walau bagaimanapun, analisis PSA mencadangkan bahawa walaupun kelajuan pengemulsi mengawal saiz GOMs, jumlah GO dalam emulsi memainkan peranan penting untuk mengekalkan kestabilan mikrokapsul. Emulsi yang dihasilkan pada 800 rpm mempunyai kestabilan yang memuaskan dengan purata saiz GOMs sekitar 11.15 ?m. Berdasarkan dapatan kajian, graphene oksida yang terkandung minyak biji rami boleh menjadi salah satu mikrokapsul penyembuh dalam sistem cat auto-sembuh.

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Phase Separation Behavior in Tough and Self-Healing Polyampholyte Hydrogels

Macromolecules ◽

10.1021/acs.macromol.0c00577 ◽

2020 ◽

Vol 53 (13) ◽

pp. 5116-5126 ◽

Cited By ~ 3

Author(s):

Kunpeng Cui ◽

Ya Nan Ye ◽

Tao Lin Sun ◽

Chengtao Yu ◽

Xueyu Li ◽

...

Keyword(s):

Phase Separation ◽

Self Healing ◽

Phase Separation Behavior ◽

Separation Behavior

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Design Strategy for Self-Healing Epoxy Coatings

Coatings ◽

10.3390/coatings10010050 ◽

2020 ◽

Vol 10 (1) ◽

pp. 50 ◽

Cited By ~ 3

Author(s):

Dian Yuan ◽

Vahab Solouki Bonab ◽

Ammar Patel ◽

Talha Yilmaz ◽

Richard A. Gross ◽

...

Keyword(s):

Molecular Weight ◽

Phase Separation ◽

Thermoplastic Polyurethane ◽

Polymeric Materials ◽

Secondary Phase ◽

Diglycidyl Ether ◽

Self Healing ◽

Structure Property ◽

Chain Entanglement ◽

Epoxy Network

Self-healing strategies including intrinsic and extrinsic self-healing are commonly used for polymeric materials to restore their appearance and properties upon damage. Unlike intrinsic self-healing tactics where recovery is based on reversible chemical or physical bonds, extrinsic self-healing approaches rely on a secondary phase to acquire the self-healing functionality. Understanding the impacts of the secondary phase on both healing performance and matrix properties is important for rational system design. In this work, self-healing coating systems were prepared by blending a bio-based epoxy from diglycidyl ether of diphenolate esters (DGEDP) with thermoplastic polyurethane (TPU) prepolymers. Such systems exhibit polymerization induced phase separation morphology that controls coating mechanical and healing properties. Structure–property analysis indicates that the degree of phase separation is controlled by tuning the TPU prepolymer molecular weight. Increasing the TPU prepolymer molecular weight results in a highly phase separated morphology that is preferable for mechanical performances but undesirable for healing functionality. In this case, diffusion of TPU prepolymers during healing is restricted by the epoxy network rigidity and chain entanglement. Low molecular weight TPU prepolymers tend to phase mix with the epoxy matrix during curing, resulting in the formation of a flexible epoxy network that benefits TPU flow while decreasing Tg and mechanical properties. This work describes a rational strategy to develop self-healing coatings with controlled morphology to extend their functions and tailor their properties for specific applications.

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Low-Temperature-Meltable Elastomers Based on Linear Polydimethylsiloxane Chains Alpha, Omega-Terminated with Mesogenic Groups as Physical Crosslinker: A Passive Smart Material with Potential as Viscoelastic Coupling. Part II—Viscoelastic and Rheological Properties

Polymers ◽

10.3390/polym12122840 ◽

2020 ◽

Vol 12 (12) ◽

pp. 2840

Author(s):

Sabina Horodecka ◽

Adam Strachota ◽

Beata Mossety-Leszczak ◽

Maciej Kisiel ◽

Beata Strachota ◽

...

Keyword(s):

Phase Separation ◽

Low Temperature ◽

Smart Materials ◽

Volume Fraction ◽

Mechanical Strain ◽

Polymer Networks ◽

Building Blocks ◽

Self Healing ◽

Structure Property ◽

Mechanical Coupling

Rheological and viscoelastic properties of physically crosslinked low-temperature elastomers were studied. The supramolecularly assembling copolymers consist of linear polydimethylsiloxane (PDMS) elastic chains terminated on both ends with mesogenic building blocks (LC) of azobenzene type. They are generally and also structurally highly different from the well-studied LC polymer networks or LC elastomers: The LC units make up only a small volume fraction in our materials and act as fairly efficient physical crosslinkers with thermotropic properties. The aggregation (nano-phase separation) of the relatively rare, small and spatially separated terminal LC units generates temperature-switched viscoelasticity in the molten copolymers. Their rheological behavior was found to be controlled by an interplay of nano-phase separation of the LC units (growth and splitting of their aggregates) and of the thermotropic transitions in these aggregates (which change their stiffness). As a consequence, multiple gel points (up to three) are observed in temperature scans of the copolymers. The physical crosslinks also can be reversibly disconnected by large mechanical strain in the ‘warm’ rubbery state, as well as in melt (thixotropy). The kinetics of crosslink formation was found to be fast if induced by temperature and extremely fast in case of internal self-healing after strain damage. Thixotropic loop tests hence display only very small hysteresis in the LC-melt-state, although the melts show very distinct shear thinning. Our study evaluates structure-property relationships in three homologous systems with elastic PDMS segments of different length (8.6, 16.3 and 64.4 repeat units). The studied copolymers might be of interest as passive smart materials, especially as temperature-controlled elastic/viscoelastic mechanical coupling.

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Synthesis of self-healing waterborne polyurethanes containing sulphonate groups

RSC Advances ◽

10.1039/c6ra28416g ◽

2017 ◽

Vol 7 (33) ◽

pp. 20093-20100 ◽

Cited By ~ 25

Author(s):

Ye Xiao ◽

Huihua Huang ◽

Xiaohong Peng

Keyword(s):

Phase Separation ◽

Waterborne Polyurethane ◽

Chain Extender ◽

Self Healing ◽

Ionic Interaction ◽

Aliphatic Diamine ◽

Waterborne Polyurethanes

An self-healing waterborne polyurethane is synthesized using the aliphatic diamine sulphonate as a hydrophilic chain-extender. The ionic interaction between the sulphonate groups and the micro-phase separation morphology realize self-healing.

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Supramolecular hydrogels based on custom-made poly(ether urethane)s and cyclodextrins as potential drug delivery vehicles: design and characterization

Journal of Materials Chemistry B ◽

10.1039/d0tb01261k ◽

2020 ◽

Vol 8 (34) ◽

pp. 7696-7712

Author(s):

Alessandro Torchio ◽

Monica Boffito ◽

Andrea Gallina ◽

Mario Lavella ◽

Claudio Cassino ◽

...

Keyword(s):

Drug Delivery ◽

Phase Separation ◽

Self Healing ◽

Potential Drug ◽

Drug Delivery Vehicles ◽

Custom Made ◽

Delivery Vehicles

A library of poly(ether urethane)-based supramolecular hydrogels was designed, showing quick gelation, no phase separation, remarkable mechanical and self-healing properties.

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From Slow to Fast Self-Healing at Ambient Temperature of High-Modulus Reversible Poly(methacrylate) Networks. Single- and Dual-Dynamics and the Effect of Phase Separation

Macromolecules ◽

10.1021/acs.macromol.1c01440 ◽

2021 ◽

Author(s):

D. Ehrhardt ◽

J. Mangialetto ◽

K. Van Durme ◽

B. Van Mele ◽

N. Van den Brande

Keyword(s):

Phase Separation ◽

Ambient Temperature ◽

Self Healing ◽

High Modulus

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Dual Microcapsulation of an Environmentally‐Friendly‐Based Reactive Multifunctional Acrylated Epoxy Resin and Thiol by Internal Phase Separation Technique for Self‐healing Applications

Journal of Polymers and the Environment ◽

10.1007/s10924-021-02085-7 ◽

2021 ◽

Author(s):

Shahla Ataei ◽

Aziz Hassan ◽

Rosiyah Yahya

Keyword(s):

Phase Separation ◽

Epoxy Resin ◽

Environmentally Friendly ◽

Separation Technique ◽

Self Healing ◽

Internal Phase

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Bulk standards for low-temperature biological x-ray microanalysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100111525 ◽

1984 ◽

Vol 42 ◽

pp. 282-283

Author(s):

P. Echlin ◽

M. McKoon ◽

E.S. Taylor ◽

C.E. Thomas ◽

K.L. Maloney ◽

...

Keyword(s):

Phase Separation ◽

Low Temperature ◽

Analytical Method ◽

Salt Solutions ◽

Absolute Concentration ◽

Cooling Process ◽

X Ray ◽

The Absolute ◽

Analytical Procedures ◽

Electrical Conductors

Although sections of frozen salt solutions have been used as standards for x-ray microanalysis, such solutions are less useful when analysed in the bulk form. They are poor thermal and electrical conductors and severe phase separation occurs during the cooling process. Following a suggestion by Whitecross et al we have made up a series of salt solutions containing a small amount of graphite to improve the sample conductivity. In addition, we have incorporated a polymer to ensure the formation of microcrystalline ice and a consequent homogenity of salt dispersion within the frozen matrix. The mixtures have been used to standardize the analytical procedures applied to frozen hydrated bulk specimens based on the peak/background analytical method and to measure the absolute concentration of elements in developing roots.

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