| 1. |
- Carlmark, Anna, et al.
(author)
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New methodologies in the construction of dendritic materials
- 2009
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In: Chemical Society Reviews. - : Royal Society of Chemistry (RSC). - 0306-0012 .- 1460-4744. ; 38:2, s. 352-362
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Research review (peer-reviewed)abstract
- Dendritic polymers are highly branched polymer structures, with complex, secondary architectures and well-defined spatial location of functional groups. Due to their unique physical and chemical features, applications in areas such as targeted drug-delivery, macromolecular carriers, catalysis, sensors, light harvesting, surface engineering and biomimetic materials have been proposed. However, only a few dendritic materials have been exploited commercially due to time consuming syntheses and the generation of significant waste/presence of unreacted starting materials. This tutorial review describes traditional synthesis of dendritic materials as well as recent advances in synthetic strategies, for example the use of Click chemistry, as a tool to efficiently obtain complex, functional dendritic structures.
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| 2. |
- Hansson, Susanne, et al.
(author)
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ARGET ATRP for Versatile Grafting of Cellulose Using Various Monomers
- 2009
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In: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 1:11, s. 2651-2659
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Journal article (peer-reviewed)abstract
- In recent years, cellulose-based materials have attracted significant attention. To broaden the application areas for cellulose, polymers are often grafted to/from the surface to modify its properties. This study applies ARGET (activators regenerated by electron transfer) ATRP (atom transfer radical polymerization) when straightforwardly grafting methyl methacrylate (MMA), styrene (St), and glycidyl methacrylate (GMA) from cellulose in the form of conventional filter paper In the presence of a sacrificial initiator. The free polymer, formed from the free initiator in parallel to the grafting, was characterized by H-1 NMR and SEC, showing that sufficient control is achieved. However, the analyses also indicated that the propagation from the surface cannot be neglected compared to the propagation of the free polymer at higher targeted molecular weights, which is an assumption often made. The grafted filter papers were evaluated with FT-IR, suggesting that the amount of polymer on the surface increased with increasing monomer conversion, which the FE-SEM micrographs of the substrates also demonstrated. Water contact angle (CA) measurements implied that covering layers of PMMA and PS were formed on the cellulose substrate, making the surface hydrophobic, in spite of low DPs. The CA of the PGMA-grafted filter papers revealed that, by utilizing either aprotic or protic solvents when washing the substrates, it was possible to either preserve or hydrolyze the epoxy groups. Independent of the solvent used, all grafted filter papers were essentially colorless after the washing procedure because of the low amount of copper required when performing ARGET ATRP. Nevertheless, surface modification of cellulose via ARGET ATRP truly facilitates the manufacturing since no thorough freeze-thaw degassing procedures are required.
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| 3. |
- Lindqvist, Josefina, et al.
(author)
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Intelligent Dual-Responsive Cellulose Surfaces via Surface-Initiated ATRP
- 2008
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In: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 9:8, s. 2139-2145
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Journal article (peer-reviewed)abstract
- Novel thermo-responsive cellulose (filter paper) surfaces of N-isopropylacrylamide (NIPAAm) and pH-responsive cellulose surfaces of 4-vinylpyridine (4VP) have been achieved via surface-initiated ATRP. Dual-responsive (pH and temperature) cellulose surfaces were also obtained through the synthesis of block-copolymer brushes of PNIPAAm and P4VP. With changes in pH and temperature, these "intelligent" surfaces showed a reversible response to both individual triggers, as indicated by the changes in wettability from highly hydrophilic to highly hydrophobic observed by water contact angle measurements. Adjusting the composition of the grafted block-copolymer brushes allowed for further tuning of the wettability of these "intelligent" cellulose surfaces.
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| 6. |
- Westlund, Robert, et al.
(author)
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Grafting liquid crystalline polymers from cellulose substrates using atom transfer radical polymerization
- 2007
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In: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-683X .- 1744-6848. ; 3:7, s. 866-871
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Journal article (peer-reviewed)abstract
- Immobilizing liquid crystalline polymers on cellulose generates new possibilities of accomplishing addressable/ responsive bio-based substrates. In this paper we report on our first steps to combine the electro-optic properties of liquid crystals with the versatility of paper as a displaying substrate. Electric current or magnetic fields can be used to manipulate the orientation of liquid crystals and thereby change the appearance and the properties of the material. Atom transfer radical polymerization ( ATRP) can be used successfully to graft polymers from solid substrates in a controlled manner. In this study it is shown that the grafting of a liquid crystalline monomer, 11-(4'-cyanophenyl-4 ''-phenoxy) undecyl acrylate, onto cellulose by ATRP is possible, and that thicker films can be obtained by using PMA as a spacer in between the cellulose and the liquid crystalline block. The cellulose fibers become highly hydrophobic subsequent to grafting and the liquid crystalline polymer possesses mesophases accessible for further processing.
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