Dextran-grafted acrylamide copolymer

Acrylamide graft copolymers such as those with starch (qv)(131), dextran (132), and lignin (qv) (133), have been studied to try to reduce copolymer costs. A general disadvantage of acrylamide copolymers is greater cost compared to partially hydroly2ed polyacrylamides. 

Polyelectrolyte and non-polyelectrolyte acrylamide random copolymers and graft copolymers of dextran with acrylamide were synthesized to evaluate the effects of polymer composition and structure on viscosity modification and solution behavior in water and brine. Polymer solution rheological behavior and precipitation properties were measured. 

The dextran-g-acrylamide sample PA-2 (Table 4) exhibited an intrinsic viscosity of 3.4 in water as compared to 0.3 for the unreacted dextran. Micro Kjeldahl analysis indicated 65% grafting (defined as weight of chain/total weight of graft copolymer x 100). 

Kutsevol, N. Bezugla, T. Bezuglyi, M. Rawiso, M. Branched Dextran-graft-Poly-acrylamide Copolymers as Perspective Materials for Nanotechnology. Macromol. Symp. 2012, 82. 317. 

Poly(amino acid)s (PAAs) have also been used in drug delivery PEO-(l-aspartic acid) block copolymer nano-associates , formed by dialysis from a dimethyl acetamide solution against water, could be loaded with vasopressin. PLA-(L-lysine) block copolymer microcapsules loaded with fluorescently labelled (FITC) dextran showed release profiles dependent on amino acid content. In a nice study, poly(glutamate(OMe)-sarcosine) block copolymer particles were surface-grafted with poly(A-isopropyl acrylamide) (PNIPAAm) to produce a thermally responsive delivery system FITC-dextran release was faster below the lower critical solution temperature (LCST) than above it. PAAs are prepared by ring-opening polymerisation of A-carboxyanhydride amino acid derivatives, as shown in Scheme 1. 

It may be of interest, that dextran-acrylamide, graft copolymers, prepared in a very similar way to starch-acrylamide, graft copolymers, donot show this aging effect, see page 28 in 3 in 6 ... 

McCormik, C.L. Park, L.S. (1981).Water-soluble copolymers. III. Dextran-g-poly(acrylamides) control of grafting sites and molecular weight by Ce(IV)-induced initiation in homogeneous solutions, J.Polym.Sci.Polym.Chem.Ed., 9,2229-22A. ... 

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