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

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389013%3A_____%2F20%3A00535690" target="_blank" >RIV/61389013:_____/20:00535690 - isvavai.cz</a>

Alternative codes found

RIV/00216208:11310/20:10442367

Result on the web

<a href="https://www.mdpi.com/2073-4360/12/12/2840" target="_blank" >https://www.mdpi.com/2073-4360/12/12/2840</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3390/polym12122840" target="_blank" >10.3390/polym12122840</a>

Result language

angličtina

Original language name

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

Original language description

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.

Czech name

—

Czech description

—

Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10404 - Polymer science

Project

<a href="/en/project/GA19-04925S" target="_blank" >GA19-04925S: Advanced smart and self-healing nanocomposite hydrogels sensitive to external stimuli</a><br>

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2020

Confidentiality

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

Name of the periodical

Polymers

ISSN

2073-4360

e-ISSN

—

Volume of the periodical

12

Issue of the periodical within the volume

12

Country of publishing house

CH - SWITZERLAND

Number of pages

31

Pages from-to

1-31

UT code for WoS article

000602471700001

EID of the result in the Scopus database

2-s2.0-85094108439