Solid-State NMR Study of the Multiphase Behavior of Linear and Cross-Linked Poly(1,3-dioxolane)

Abstract

The multiphase behavior of poly(1,3-dioxolane) (polyDXL) in linear and network forms as a function of molecular weight and cross-link density of the samples was investigated by high-resolution solid-state 13C NMR. The ability to introduce two acrylate end groups and to control the molecular weight of the polymer provided a unique way to synthesize polyDXL networks with molecular weights varying from 4000 to 9000 between the cross-links. Besides an elastomeric phase and a crystalline phase, the existence of a third phase with intermediate molecular mobility could be shown for cross-linked polyDXL. This could be realized by making use of different techniques, such as T 1 ρ H studies at well-selected contact times and careful Lorentzian deconvolution of the acetal 13C CP/MAS resonance lines. In these OCH2O resonances, the peak of the interphase is situated around 96 ppm, at about the same chemical shift as that of the elastomeric phase, but it has a broader bandwidth due to increased spin diffusion. The crystalline component having the broadest bandwidth is positioned around 93.4 ppm. While the introduction of cross-links clearly is attributed to the development of an interphase, T 1 ρ H studies demonstrated that the limited molecular mobility of this phase is independent of the cross-link density of the samples. The presence of such a noncrystalline, immobile interphase between the crystalline and elastomeric regions could not be demonstrated for linear polyDXL with a molecular weight range of 4000−9000.

Comparative Morphological Study of Poly(dioxolane)/Poly(methyl methacrylate) Segmented Networks and Blends by 13C Solid-State NMR and Thermal Analysis

“…The presence of small crystalline PDXL domains in the PDXL phase, as already demonstrated by DSC, should also be reflected in the T 1 ρ H decay times of these blends. Indeed, the two PDXL decay times can be assigned in accordance with a previous study on linear PDXL and PDXL networks . In this study, a T 1 ρ H decay time of 5.7 and 1.1 ms was observed for the amorphous and crystalline PDXL domains, respectively.…”

“…Indeed, the two PDXL decay times can be assigned in accordance with a previous study on linear PDXL and PDXL networks. 28 In this study, a T 1FH decay time of 5.7 and 1.1 ms was observed for the amorphous and crystalline PDXL domains, respectively. Consequently, the T 1FH L (6.8 ms) and T 1FH S (1.6 ms) can be ascribed to the mobile, elastomeric and rigid crystalline PDXL domains, respectively.…”

Genotype evaluation of cowpea seeds (Vigna unguiculata) using 1H qNMR combined with exploratory tools and solid-state NMR

“…However, the 1 H T 1ρ values was different, which is the 13 C decay governed by the rate of the 1 H relaxation time during spin-lock at longer contact times. The 1 H T 1ρ are sensitive to the motion of the proton system in short distances (intermolecular interactions) reflecting the motion of the segments in the multiphase system (Du Prez, Goethals, Adriaensens, Gelan, & Vanderzande, 1996). Therefore, the value of the 1 H T 1ρ increases with the increase of the molecular mobility of the phases as observed in the study of tropical seeds starches (de Miranda Costa, Bruno Tavares, Bathista, da Silva, & Nogueira, 2007;Maciel & Tavares, 2010;Tavares, Bathista, Silva, Filho, & Nogueira, 2003).…”

Solid‐State 1H NMR Studies of Degradable Poly(ethylene oxide) Based Hydrogels

“…The method has been extended to numerous other systems including amphiphilic networks9 or PEO hydrogels with charged groups at the network junction points 10. Since poly(1,3‐dioxolane) (PDXL) [(CH 2 CH 2 OCH 2 O) n ] is another hydrophilic nonionic polymer well soluble in water, the same approach was extensively used for the preparation of segmented degradable PDXL hydrogels 11–14…”