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A series of amphiphilic conetworks of methacrylic acid (MAA) and methyl methacrylate (MMA) were synthesized using group transfer polymerization (GTP). The MAA units were introduced via the polymerization of tetrahydropyranyl methacrylate (THPMA), followed by the removal of the protecting tetrahydropyranyl group by acid hydrolysis after network formation. 1,4-Bis(methoxytrimethylsiloxymethylene)-cyclohexane (MTSCH) was used as a bifunctional GTP initiator, while ethylene glycol dimethacrylate (EGDMA) served as the cross-linker. Nine of the conetworks were model conetworks, comprising copolymer chains between the cross-links of precise molecular weight and composition. Eight of the model conetworks were based on ABA triblock copolymers, while the ninth was based on a statistical copolymer. The tenth conetwork was not model but randomly cross-linked. The molecular weight and the composition of the linear conetwork precursors were analyzed by gel permeation chromatography and 1H NMR, respectively, and were found to bear values close to the theoretically expected. FTIR spectroscopic analyses indicated complete polymerization of the EGDMA cross-linker vinyl units and complete hydrolysis of the THPMA units. The degrees of swelling (DS) of all the conetworks were measured in water and in THF as a function of the degree of ionization (DI) of the MAA units. The DSs in water increased with the DI of the MAA units (and the pH), while the DSs in THF presented the opposite trend. Finally, small-angle neutron scattering and atomic force microscopy confirmed nanophase separation in a triblock copolymer-based model conetwork and lack of it in its statistical copolymer counterpart. © 2007 American Chemical Society. 40 6 2192 2200 Cited By :67

The structure of two series of model amphiphilic polymer conetworks based on the hydrophilic anionic methacrylic acid was characterized by atomic force microscopy (AFM) and small-angle neutron scattering (SANS). In the first series, the hydrophobic component was the glassy poly(methyl methacrylate), while the rubbery poly(2-butyl-1-octyl methacrylate) constituted the hydrophobic segments in the second series. Each series comprised conetworks in which the hydrophile / hydrophobe ratio was systematically varied as well as conetworks with different architecture of the linear chain: ABA and BAB triblock and statistical. The AFM and SANS measurements indicated nanophase separation in the triblock copolymer-based conetworks and provided the spacing, size and shape of the formed nanodomains. © 2008 American Chemical Society. 996 286 302 Cited By :2

Seven amphiphilic conetworks of methacrylic acid (MAA) and a new hydrophobic monomer, 2-butyl-1-octyl-methacrylate (BOMA), were synthesized using group transfer polymerization. The MAA units were introduced via the polymerization of tetrahydropyranyl methacrylate (THPMA) followed by the removal of the protecting tetrahydropyranyl group by acid hydrolysis after network formation. Both THPMA and BOMA were in-house synthesized. Ethylene glycol dimethacrylate (EGDMA) was used as the cross-linker. Six of the conetworks were model conetworks, containing copolymer chains between cross-links of precise molecular weight and composition. The prepared conetwork series covered a wide range of compositions and architectures. In particular, the MAA content was varied from 67 to 94 mol %, and three different conetwork architectures were constructed: ABA triblock copolymer-based, statistical copolymer-based, and randomly cross-linked. The linear conetwork precursors were analyzed by gel permeation chromatography and 1H NMR spectroscopy in terms of their molecular weight and composition, both of which were found to be close to the theoretically calculated values. The degrees of swelling (DS) of all the amphiphilic conetworks were measured in water and in THF over the whole range of ionization of the MAA units. The DSs in water increased with the degree of ionization (DI) and the content of the hydrophilic MAA units in the conetwork, while the DSs in THF increased with the degree of polymerization of the chains between the cross-links and by reducing the DI of the MAA units. Finally, the nanophase behavior of the conetworks was probed using small-angle neutron scattering and atomic force microscopy. © 2007 American Chemical Society. 23 21 10746 10755 Cited By :65

Two series of model amphiphilic polymer conetworks were synthesized by group transfer polymerization (GTP). The first one contained methyl methacrylate (MMA) and the second one 2-butyl-l-octyl methacrylate (BOMA) as hydrophobic monomers. Methacrylic acid (MAA) was used as the hydrophilic monomer for both series. Network synthesis was performed by sequential monomer/cross-linker additions to form conetworks in a wide range of compositions and architectures. All conetwork precursors and the extractables were characterized in organic solvents by gel permeation chromatography and 1H NMR. The polymer conetworks were investigated in terms of their degree of swelling in aqueous media and in THF. The nanophase separated structure was proved by atomic force microscopy and small-angle neutron scattering measurements for the triblock copolymer model conetworks. 2 60 63

The use of spin-diffusion NMR for the measurement of domain sizes in multiphase materials is becoming increasingly popular, in particular for the study of heterogeneous polymers. Under conditions where T1 relaxation can be neglected, which is mostly the case at high field, analytical and approximate solutions to the evolution of spin diffusion are available. In order to extend the technique to more general conditions, we performed a comprehensive study of the diffusion of magnetization in a model copolymer at low field, where T1 tends to be of the same order of magnitude as the typical spin-diffusion time. In order to study the effects of T1 and to delineate the optimal T1 values for back correction prior to applying the initial-rate approximation, we developed a numerical simulation based on the diffusion equation and including longitudinal relaxation. We present and discuss the limits of simple correction strategies for initial-slope analysis based on apparent relaxation times from saturation-recovery experiments or the spin-diffusion experiments themselves. Our best strategy faithfully reproduces domain sizes obtained by both TEM investigations and full simultaneous fitting of spin-diffusion and saturation-recovery curves. Full fitting of such independent data sets not only yields correct domain sizes, but also the true longitudinal relaxation times, as well as spin-diffusion coefficients. Effects of interphases with distinct mobility on spin-diffusion curves, as well as practical hints concerning the reliable component decomposition of the detected low-resolution FID signal by help of different magnetization filters are also discussed in detail. © 2008 Elsevier Inc. All rights reserved.