Tunable damping of magnetorheological elastomers based on particles controllably grafted with polymer chains

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F70883521%3A28610%2F16%3A63522138" target="_blank" >RIV/70883521:28610/16:63522138 - isvavai.cz</a>

Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Tunable damping of magnetorheological elastomers based on particles controllably grafted with polymer chains

Popis výsledku v původním jazyce

Magnetorheological elastomers (MREs) are widely-known as intelligent systems comprising ferromagnetic particles embedded in an elastomeric matrix. Such materials exhibit rapid reversible and tunable changes of their viscoelastic moduli, which make these composites suitable for applications as vibration absorbers, adaptive dampers, stiffness tunable mounts etc.[1] To fabricate an efficient MRE several factors have to be considered including particle concentration, particle size, or matrix properties. Nevertheless, exceptionally important feature is the compatibility of the particles with the matrix, which is essential for reasonable stress transfer reflected in high damping. Recently it was found, that stress transfer can be modulated by an incorporation of the particles treated with various surfactants such as fatty acids, calcium and aluminum soaps, respectively.[2] However, the introduction of surfactants into MRE systems can initiate several issues related to their diffusion through the matrix as they are not covalently bonded onto the particle surface. Moreover, using surfactants it is not possible to protect the incorporated particles against acidic environment or high temperatures. In this work, the carbonyl iron (CI) particles were modified with (3-aminopropyl)triethoxysilane, followed by the immobilization of α-bromoisobutyryl bromide initiator. Finally, they were grafted with poly(trimethylsilyloxyethyl methacrylate) (PHEMATMS) using surface-initiated atom transfer radical polymerization (SI-ATRP). Two variants of the particles differing in chain lengths were prepared – with polymer grafts of 9 800 g·mol–1 (CI-g-PHEMATMS-1) and 17 900 g·mol–1 (CI-g-PHEMATMS-2). The particles were mixed with polydimethyl siloxane (PDMS) matrix and the isotropic MREs were fabricated. It was found, that the presence of PHEMATMS chains increased mobility of the CI particles within the PDMS matrix. This phenomenon was more pronounced in the sample based on CI-g-PHEMATMS-2 probably due to better polymer shell entanglements with PDMS chains. The increased particle mobility was reflected in considerably increased efficiency of magnetorheological (MR) effect. The MRE based on bare CI possessed the MR effect of 42.8 %, while their analogues based on CI-g-PHEMATMS-1 and CI-g-PHEMATMS-2 exhibited 66.0 % and 76.2 %, respectively. Using the SI-ATRP we were able to tailor mobility of the embedded particles and hence a friction represented by the increase of the damping factor. Finally, chemical resistance and thermo-oxidation stability of the particles was enhanced at the same time, which makes prepared MREs promising for practical applications.

Název v anglickém jazyce

Tunable damping of magnetorheological elastomers based on particles controllably grafted with polymer chains

Popis výsledku anglicky

Magnetorheological elastomers (MREs) are widely-known as intelligent systems comprising ferromagnetic particles embedded in an elastomeric matrix. Such materials exhibit rapid reversible and tunable changes of their viscoelastic moduli, which make these composites suitable for applications as vibration absorbers, adaptive dampers, stiffness tunable mounts etc.[1] To fabricate an efficient MRE several factors have to be considered including particle concentration, particle size, or matrix properties. Nevertheless, exceptionally important feature is the compatibility of the particles with the matrix, which is essential for reasonable stress transfer reflected in high damping. Recently it was found, that stress transfer can be modulated by an incorporation of the particles treated with various surfactants such as fatty acids, calcium and aluminum soaps, respectively.[2] However, the introduction of surfactants into MRE systems can initiate several issues related to their diffusion through the matrix as they are not covalently bonded onto the particle surface. Moreover, using surfactants it is not possible to protect the incorporated particles against acidic environment or high temperatures. In this work, the carbonyl iron (CI) particles were modified with (3-aminopropyl)triethoxysilane, followed by the immobilization of α-bromoisobutyryl bromide initiator. Finally, they were grafted with poly(trimethylsilyloxyethyl methacrylate) (PHEMATMS) using surface-initiated atom transfer radical polymerization (SI-ATRP). Two variants of the particles differing in chain lengths were prepared – with polymer grafts of 9 800 g·mol–1 (CI-g-PHEMATMS-1) and 17 900 g·mol–1 (CI-g-PHEMATMS-2). The particles were mixed with polydimethyl siloxane (PDMS) matrix and the isotropic MREs were fabricated. It was found, that the presence of PHEMATMS chains increased mobility of the CI particles within the PDMS matrix. This phenomenon was more pronounced in the sample based on CI-g-PHEMATMS-2 probably due to better polymer shell entanglements with PDMS chains. The increased particle mobility was reflected in considerably increased efficiency of magnetorheological (MR) effect. The MRE based on bare CI possessed the MR effect of 42.8 %, while their analogues based on CI-g-PHEMATMS-1 and CI-g-PHEMATMS-2 exhibited 66.0 % and 76.2 %, respectively. Using the SI-ATRP we were able to tailor mobility of the embedded particles and hence a friction represented by the increase of the damping factor. Finally, chemical resistance and thermo-oxidation stability of the particles was enhanced at the same time, which makes prepared MREs promising for practical applications.

Druh

O - Ostatní výsledky

CEP obor

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OECD FORD obor

10404 - Polymer science

Projekt

<a href="/cs/project/LO1504" target="_blank" >LO1504: Centrum polymerních systémů plus</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)<br>S - Specificky vyzkum na vysokych skolach

Rok uplatnění

2016

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů