Temperature responsive cellulose-graft-copolymers via cellulose functionalization in an ionic liquid and RAFT polymerization.
Well-defined cellulose-graft-polyacrylamide copolymers were synthesized in a grafting-from approach by reversible addition-fragmentation chain transfer polymerization (RAFT). A chlorine moiety (degree of substitution DS(Cl) ≈ 1.0) was introduced into the cellulose using 1-butyl-3-methylimidazolium chloride (BMIMCl) as solvent before being substituted by a trithiocarbonate moiety resulting in cellulose macro-chain transfer agents (cellulose-CTA) with DS(RAFT) of 0.26 and 0.41. Poly(N,N-diethylacrylamide) (PDEAAm) and poly(N-isopropylacrylamide) (PNIPAM) were subsequently grafted from these cellulose-CTAs and the polymerization kinetics, the molecular weight characteristics and the product composition were studied by nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and size exclusion chromatography of the polyacrylamides after cleavage from the cellulose chains. The number-average molecular weights, Mn, of the cleaved polymers ranged from 1100 to 1600 g mol(-1) for PDEAAm (dispersity Đ = 1.4-1.8) and from 1200 to 2600 g mol (-1) for PNIPAM (Đ = 1.7-2.1). The LCST behavior of the cellulose-graft-copolymers was studied via the determination of cloud point temperatures, evidencing that the thermoresponsive properties of the hybrid materials could be finely tuned between 18 and 26 °C for PDEAAm and between 22 and 26 °C for PNIPAM side chains.
Preparative Macromolecular Chemistry, Institut für Technische Chemie und Polymerchemie, Karlsruhe Institute of Technology (KIT) , Engesserstr. 18, 76128 Karlsruhe, Germany.
Andrea
A
Hufendiek
Vanessa
V
Trouillet
Michael A R
MA
Meier
Christopher
C
Barner-Kowollik
D000178:Acrylamides / Q000737:chemistry; D000180:Acrylic Resins / Q000737:chemistry; D002482:Cellulose / Q000031:analogs & derivatives* / Q000138:chemical synthesis*; D007093:Imidazoles / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry; D007700:Kinetics; D058105:Polymerization; D011108:Polymers / Q000737:chemistry; D013696:Temperature
D000178:Acrylamides; D000180:Acrylic Resins; D007093:Imidazoles; D052578:Ionic Liquids; D011108:Polymers; C428028:poly(N,N-diethylacrylamide); C052970:poly-N-isopropylacrylamide; C502841:1-butyl-3-methylimidazolium chloride; D002482:Cellulose