| People | Locations | Statistics |
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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Torkelson, John M.
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (14/14 displayed)
- 2022Functional enzyme–polymer complexescitations
- 2011Effect of gradient sequencing on copolymer order-disorder transitionscitations
- 2009Melt rheology and x-ray analysis of gradient copolymers
- 2009Glass transition breadths and composition profiles of weakly, moderately, and strongly segregating gradient copolymerscitations
- 2008Microphase separation and shear alignment of gradient copolymerscitations
- 2006Confinement, composition, and spin-coating effects on the glass transition and stress relaxation of thin films of polystyrene and styrene-containing random copolymerscitations
- 2005Impacts of polystyrene molecular weight and modification to the repeat unit structure on the glass transition-nanoconfinement effect and the cooperativity length scalecitations
- 2005On the glass transition and physical aging in nanoconfined polymers
- 2004Erratumcitations
- 2004Effects of free-surface and interfacial layers and plasticizer content on the distribution of glass transition temperatures in nanoconfined polymers
- 2004Dramatic reduction of the effect of nanoconfinement on the glass transition of polymer films via addition of small-molecule diluentcitations
- 2004In situ monitoring of sorption and drying of polymer films and coatingscitations
- 2003The distribution of glass-transition temperatures in nanoscopically confined glass formerscitations
- 2002Sensing the glass transition in thin and ultrathin polymer films via fluorescence probes and labelscitations
Places of action
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article
Glass transition breadths and composition profiles of weakly, moderately, and strongly segregating gradient copolymers
Abstract
<p>Gradient copolymers are prepared from comonomer systems with a range of segregation strengths and homopolymer glass transition temperature (T <sub>g</sub>) differences to explore the breadths that can be achieved by their single, continuous glass transition regions compared to random and block copolymers. A variety of chain architectures are synthesized using semibatch nitroxide-mediated controlled radical polymerization, including linear gradients, sigmoidal gradients, blocky gradients, and blocky random cases. The derivative of the differential scanning calorimetry heat curve is used to extract T <sub>g</sub> breadths (ΔT <sub>g</sub>s). For the first time, these T <sub>g</sub> breadths are compared against values derived from nanophase separation levels predicted by self-consistent mean-field theory and found to be in good accord. In moderately segregating systems (styrene (S)/n-butyl acrylate and S/tert-butyl acrylate), ΔT <sub>g</sub> may be tuned dramatically via gradient structure and molecular weight; e.g., a T <sub>g</sub> breadth exceeding 100 °C, or >65% of the homopolymer T <sub>g</sub> difference, is obtained with a sigmoidal gradient copolymer of S/n-butyl acrylate. In the very weakly segregating system (S/n-butyl methacrylate), ΔT <sub>g</sub> remains narrow (<40% of the homopolymer T <sub>g</sub> difference), regardless of gradient design. In strongly segregating systems (S/4-vinylpyridine and S/4-acetoxystyrene (AS)), ΔT <sub>g</sub>s are observed spanning 70-80% of the homopolymer T <sub>g</sub> difference. Smallangle X-ray scattering applied to S/AS materials demonstrates a range of temperature-sensitive scattering intensities consistent with the level of segregation observed through their ΔT <sub>g</sub>s.</p>