Facile, Contolled, Room-Temperature RAFT Polymerization of N-Isopropylacrylamide

• Published in: Biomacromolecules
• Main Authors: Convertine, Anthony J., Ayres, Neil, Scales, Charles W., Lowe, Andrew B., McCormick, Charles L.
• Format: Text
• Language: unknown
• Published: Scholars' Mine 2004
• Subjects: Drug dosage; Homopolymerization; Macromolecules; Size exclusion chromatography; Thermal effects; Chain transfer agents (CTA); Drug delivery; Organic polymers; 2,2' azobis(2,4 dimethylvaleronitrile); carbonic acid derivative; dodecyl sulfate; n,n dimethylformamide; poly(n isopropylacrylamide); thiol derivative; acrylamide derivative; azo compound; n isopropylacrylamide; N-isopropylacrylamide; propionic acid derivative; article; chemical analysis; chemical reaction; chromatography; controlled study; drug delivery system; fragmentation reaction; high temperature procedures; molecular size; polymerization; priority journal; reaction analysis; room temperature; scientific literature; chemical structure; chemistry; synthesis; temperature; Acrylamides; Azo Compounds; Dimethylformamide; Molecular Structure; Propionic Acids; Materials Science and Engineering; Carbonic acid
• Online Access: https://scholarsmine.mst.edu/matsci_eng_facwork/2271; https://doi.org/10.1021/bm049825h

Poly (N-isopropyl acrylamide) is a thermoresponsive polymer that has been widely investigated for drug delivery. Herein, we report conditions facilitating the controlled, room-temperature RAFT polymerization of N-isopropylacrylamide (NIPAM). The key to success is the appropriate choice of both a suitable RAFT chain transfer agent (CTA) and initiating species. We show that the use of 2-dodecylsulfanylthiocarbonyl-sulfanyl-2-methyl propionic acid, a trithiocarbonate RAFT CTA, in conjunction with the room-temperature azo initiator 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile), in DMF, at 25 °C, yields conditions leading to NIPAM homopolymerizations which bear all of the characteristics of a controlled/"living" polymerization. We also demonstrate facile size exclusion chromatographic analysis of PNIPAM samples in DMF at 60 °C, directly on aliquots withdrawn during the polymerizations, which avoids the problems previously reported in the literature.