Izvorni znanstveni članak
Jelena ČULIN
orcid.org/0000-0002-1074-9336
; Institut Ruđer Bošković, Zagreb
Mladen ANDREIS
; Institut Ruđer Bošković, Zagreb
Zorica VEKSLI
orcid.org/0000-0003-4527-629X
; Institut Ruđer Bošković, Zagreb
Alojz ANŽLOVAR
; Kemijski Inštitut, Ljubljana, Slovenija
Majda ŽIGON
; Kemijski Inštitut, Ljubljana, Slovenija
Sažetak
The electron spin resonance, ESR-spin probe method was applied to study semi-interpenetrating polymer networks, SIPNs and mixtures on the basis of polyester polyurethanes, PU, with carboxylic groups and methacrylic copolymers, PM, with tertiary amine groups. The concentration of functional groups in prepolymers varied from 0 to 0.45 mmol g-1. From the temperature dependent composite ESR spectra motional heterogeneity and phase separation depending on the functional group concentration were deduced. The spin probes embedded within domains with larger free volume or soft domains correspond to the fast motional component, while the slow motion describes spin probes in the regions of smaller free volume characteristic for the glassy polymers. According to the ratio of fast and slow components, free volume decreases with an increase of functional groups concentration in both polymer mixtures and networks. Restriction of spin probe motion or decreased available free volume in polymer networks in comparison with polymer mixtures of the same composition is a consequence of additional crosslinking in the networks. The differences in spin probe motion due to the available free volume are related to the diffusion of small molecules in polymer matrices.
Ključne riječi
electron spin resonance; functional groups; molecular dynamics; polymer mixtures; polymethacrylates; polyurethanes; semi-interpenetrating polymer networks; spin probe
Hrčak ID:
12941
URI
Datum izdavanja:
4.3.2005.
Posjeta: 1.756 *