Selectively Dendronized Cellulose: Synthesis and Characterization

Abstract

Selectively dendronized cellulose at C‐6 was synthesized homogeneously (in DMSO) and heterogeneously (in methanol) by the conversion of 6‐azido‐6‐deoxy cellulose (degree of substitution, DS 0.75) with polyamidoamine (PAMAM) dendrons possessing an ethynyl focal moiety via the copper‐catalyzed Huisgen reaction (click reaction) under mild conditions. First to third generation of PAMAM‐triazolo cellulose derivatives with DS values of up to 0.69 could be prepared, which are soluble in organic solvents (DMSO, DMF) and in water. The novel biopolymer derivatives were characterized by elemental analysis, FTIR, and NMR spectroscopic methods, showing no impurities and no conversion at the secondary positions.

Defined Chitosan-based networks by C-6-Azide–alkyne “click” reaction

“…In recent literature the interest has been shown in this cycloaddition for the modification of polysaccharides. It was used for the functionalization of curdlan [39][40][41], cellulose [42][43][44], dextran [45] and starch [46]. This was further used to prepare hydrogels from hyaluronic acid (HA) [47], for the functionalization of chitosan-grafted-PEG nanostructures [48], to obtain microparticles and block copolymers from dextran [49,50], and to synthesizes graft copolymers and crosslinked products from functionalized poly(ethylene glycol) (PEG) and guar gum [51].…”

Novel Biopolymer Structures Synthesized by Dendronization of 6‐Deoxy‐6‐aminopropargyl cellulose

“…In the frame of our studies to design novel polymeric structures based on cellulose, alternative synthesis paths including nucleophilic displacement (S N )‐ and 1,3‐dipolar cycloaddition reactions are studied 8, 9. Thus, 6‐deoxy‐6‐azido cellulose, obtained via S N reaction starting from toluenesulfonyl cellulose ester (cellulose tosylate), was modified with polyamido amine (PAMAM) dendrons possessing an ethynyl focal moiety via the copper‐catalyzed Huisgen reaction (1,3‐dipolar cycloaddition) both under homogeneous and heterogeneous conditions 10, 11. Another promising approach in this context may be the introduction of a carbon‐carbon triple bond into cellulose and subsequent dendronization.…”

“Click” reactions in polysaccharide modification

“…Encouraged by these results, derivatives with more diverse architectures including graft [36,44,46,59,67], block [61][62][63], and dendronized [37,68] copolymers have been synthesized via CuAAC. Copolymerization of two or more macromolecules may not only combine the properties of the polymers, but may also generate new properties.…”