Free-radical functionalized polysaccharides
Polysaccharides are functionalized using a source of free radicals which forms stable radicals on the polysaccharides structure and wherein the formed radicals reacts with a functionalized unsaturated compound. The method comprises two steps: a first step, wherein the free radical on the polysaccharides chain is formed, and a second step, wherein said radical reacts with the unsaturated compound in the absence of the radical source.
1. A process for the preparation of functionalized polysaccharides or polymer fibers comprising:
a) forming stable radicals on a polysaccharide from a chemical free radical source wherein the chemical source is Fenton's reagent;
b) washing the reaction mixture of step a) containing the polysaccharide chain having a free radical with water and recovering said polysaccharide; and
c) reacting, in the absence of the free radical source, an olefin containing a functional group with the stable radicals on the polysaccharide.
2. The method of claim 1 , wherein the olefin containing a functional group is selected from the group consisting of glycidylmethacrylate and allylglycidylether.
3. The method of claim 1 , further comprising filtering the washed reaction mixture.
4. A method for functionalizing polysacoharides using a chemical source of free radicals, which forms stable radicals on a polysaccharide structure wherein at least one of the formed radicals reacts with a functionalized olefin, comprising:
a first step, wherein a free radical on a polysaccharide chain is formed, washing the reaction mixture of the first step containing the polysaccharide chain having a free radical with water and recovering said polysaccharide, and
a second step, wherein said radical reacts with an the functionalized olefin in the absence of the chemical source of free radicals a radical source; wherein
the polysaccharide is in the form of a fiber;
the amount of functional groups introduced in the polysaccharide is between 10 −3 and 2 mol olefin/eq anhydrous glucose; and the chemical source is Fenton's reagent.
5. Method according to claim 1 , wherein the polysaccharide is selected from the group consisting of flax fibers, cellulose, viscose and cotton fibers.
6. Method according to claim 5 , wherein the polysaccharide is used together with one or more natural or synthetic fibers.
7. Method according to claim 6 , wherein the natural or synthetic fibers are selected from silk, polyamide, polyester, polyacrylate and polyolefin.
8. Method according to claim 1 , wherein the stable radicals have a half-life of about 1 day.
9. Method according to claim 1 , wherein the amount of functional groups introduced in the polysaccharide is between 10 −2 and 1 mol olefin/eq anhydrous glucose.
10. The method of claim 1 , wherein the functionalized olefin is selected from the group consisting of glycidylmethacrylate and allylglycidylether.
11. The method of claim 1 , further comprising filtering the washed reaction mixture.