| 1. |
- Leppänen, Ann-Sofie, et al.
(författare)
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Anionic Polysaccharides as Templates for the Synthesis of Conducting Polyaniline and as Structural Matrix for Conducting Biocomposites
- 2013
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Ingår i: Macromolecular rapid communications. - : Wiley. - 1022-1336 .- 1521-3927. ; 34:13, s. 1056-1061
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Tidskriftsartikel (refereegranskat)abstract
- A green chemoenzymatic pathway for the synthesis of conducting polyaniline (PANI) composites is presented. Laccase-catalyzed polymerization in combination with anionic polysaccharides is used to produce polysaccharide/PANI composites, which can be processed into flexible films or coated onto cellulose surfaces. Different polysaccharide templates are assessed, including -carrageenan, native spruce O-acetyl galactoglucomannan (GGM), and TEMPO-oxidized cellulose and GGM. The resulted conducting biocomposites derived from natural materials provide a broad range of potential applications, such as in biosensors, electronic devices, and tissue engineering.
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| 2. |
- Leppänen, Ann-Sofie, et al.
(författare)
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Targeted allylation and propargylation of galactose-containing polysaccharides in water
- 2014
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 100, s. 46-54
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Tidskriftsartikel (refereegranskat)abstract
- Galactose units of spruce galactoglucomannan (GGM), guar galactomannan (GM), and tamarind (galacto)xyloglucan (XG) were selectively allylated. Firstly aldehyde functionalities were formed at the C-6 position via enzymatic oxidation by galactose oxidase. The formed aldehydes were further derivatized by an indium mediated Barbier-Grignard type reaction, resulting in the formation of homoallylic alcohols. In addition to allylic halides, the same reaction procedure was also applicable for GGM, when using propargyl bromide as halide. All reaction steps were done in water, thus the polysaccharides were modified in a one-pot reaction. The formation of the allylated, or propargylated, product was identified by MALDI-TOF-MS. All polysaccharide products were isolated and further characterized by GC-MS or NMR spectroscopy. By this chemo-enzymatic process, we have demonstrated a novel method for derivatization of GGM and other galactose-containing polysaccharides. The derivatized polysaccharides are potential platforms for further functionalizations.
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| 3. |
- Leppänen, Ann-Sofie, et al.
(författare)
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Targeted functionalization of spruce O-acetyl galactoglucomannans-2,2,6,6-tetramethylpiperidin-1-oxyl-oxidation and carbodiimide-mediated amidation
- 2013
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 0021-8995 .- 1097-4628. ; 130:5, s. 3122-3129
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Tidskriftsartikel (refereegranskat)abstract
- Modified spruce O-acetyl galactoglucomannans (GGMs) can be used as molecular anchors to alter the surface properties or to activate the surface of cellulose. To selectively introduce functionalities, GGMs were oxidized on C-6 of hexoses by 2,2,6,6-tetramethylpiperidin-1-oxyl-mediated oxidation. Different degrees of oxidation were successfully obtained by varying the reaction parameters. Low degrees could be obtained by performing the oxidations in bromide-free conditions. The formed uronic acids were further modified by a carbodiimide-mediated amidation reaction, which opens a window for introducing various functionalities selectively on hexoses. The adsorption of the modified GGMs to various cellulose samples was investigated. Indirect bulk sorption to fibers was compared to direct adsorption to nanofibrillated cellulose ultrathin films. GGMs with low degrees of oxidation showed high affinity to cellulose surfaces and could be sorbed onto cellulose in pure water. Moderate amounts of GGMs with high degree of oxidation could be sorbed onto cellulose in the presence of salts.
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