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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/2425

Title: Solid state NMR study of segmented polymer networks: fine-tuning of phase morphology via their molecular design
Authors: Lequieu, W
Van de Velde, P
Du Prez, FE
STORME, Liesbet
Issue Date: 2004
Citation: POLYMER, 45(23). p. 7943-7951
Abstract: Segmented polymer networks (SPNs) based on thermo-sensitive poly(N-isopropyl acryl amide) (PNIPAA) and poly(tetrahydrofuran) (PTHF) have been synthesized by free radical copolymerization of PTHF bis-macromonomers with N-isopropyl acrylamide. The nature of the polymerizable end group on the bis-macromonomer has been varied, respectively from acrylate to acrylamide end groups. The multiphase behaviour of the corresponding SPNs has been examined as a function of the nature of the end group by making use of solid-state C-13 CP/MAS NMR relaxometry, H-1 wideline NMR relaxometry and dynamic mechanical analysis (DMA). When PTHF with acrylate end groups was used during the SPN formation, analysis of proton spin-lattice relaxation times (T-1H) and proton spin-lattice relaxation times in the rotating frame (T-1pH) revealed phase separation with domain sizes larger than 5 nm when the PTHF fraction exceeds 10 wt%. Only for lower PTHF-amounts, the SPNs were homogeneous on the nanometer scale. On the other hand, when PTHF with acrylamide end groups was used as macromolecular cross-linker, the NMR results showed the absence of any domain formation for SPNs with PTHF fractions up to 50 wt%. The major impact of the molecular design on the ultimate phase morphology of bicomponent polymer networks has been confirmed in all cases by DMA-analysis.
Notes: State Univ Ghent, Dept Organ Chem, Polymer Chem Res Grp, B-9000 Ghent, Belgium. Limburgs Univ Ctr, Div Chem, Mat Res Inst, IMO, B-3590 Diepenbeek, Belgium.Du Prez, FE, State Univ Ghent, Dept Organ Chem, Polymer Chem Res Grp, Krigslaan 281 S4bis, B-9000 Ghent, Belgium.filip.duprez@ugent.be
URI: http://hdl.handle.net/1942/2425
DOI: 10.1016/j.polymer.2004.09.024
ISI #: 000224813900017
ISSN: 0032-3861
Category: A1
Type: Journal Contribution
Validation: ecoom, 2005
Appears in Collections: Research publications

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