A High-Field EPR Study of the Accelerated Dynamics of the Amorphous Fraction of Semicrystalline Poly(dimethylsiloxane) at the Melting Point

• Published in: Applied magnetic resonance Vol. 45; no. 7; pp. 693 - 706
• Main Authors: Massa, Carlo Andrea, Pizzanelli, Silvia, Bercu, Vasile, Pardi, Luca, Bertoldo, Monica, Leporini, Dino
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.07.2014; Springer Nature B.V
• Subjects: Atoms and Molecules in Strong Fields; Crystallites; Crystallization; Electron paramagnetic resonance; Glass transition; Laser Matter Interaction; Magnetic fields; Melting points; Organic Chemistry; Physical Chemistry; Physics; Physics and Astronomy; Polydimethylsiloxane; Solid State Physics; Spectroscopy/Spectrometry; Spectrum analysis; Temperature; Viscoelasticity; Correlation Time; Tempo; Electron Paramagnetic Resonance; Structural Relaxation; PDMS
• ISSN: 0937-9347; 1613-7507
• DOI: 10.1007/s00723-014-0547-1

The reorientation of a small paramagnetic tracer in poly(dimethylsiloxane) (PDMS) has been investigated by high-field electron paramagnetic resonance spectroscopy at a Larmor frequency of 285 GHz. The tracer is confined in the disordered phase of the semicrystalline PDMS. A sudden change of the rotational dynamics is observed close to the melting point (213 K) of the crystallites. This points to strong coupling between the crystalline and the disordered fractions of PDMS. Below the glass transition ( T g ∼ 150 K ), the tracer reorientation occurs via small angle jumps, with no apparent distribution of the correlation times. Above T g , a power-law distribution of correlation times is evidenced.