title: Biomimetic stimulus-responsive star diblock gelators.
abstract: Novel biomimetic gelators with star diblock copolymer architectures have been synthesized by atom-transfer radical polymerization (ATRP). Two types of trifunctional ATRP initiator were used to polymerize 2-(methacryloyloxy)ethyl phosphorylcholine [MPC] at 20 degrees C, followed by sequential monomer addition of various tertiary amine methacrylates or mixtures thereof. Poor living character was achieved using an amide-based trifunctional initiator, but the analogous triester initiator gave reasonably well-defined thermo-responsive and pH-responsive star diblock copolymers. The most effective thermo-responsive gelators were obtained by the statistical terpolymerization of 2-(dimethylamino)ethyl methacrylate [DMA], 2-(diethylamino)ethyl methacrylate [DEA], and a monomethoxy-capped poly(propylene oxide) methacrylate [PPOMA], whereas pH-responsive gelators were prepared using 2-(diisopropylamino)ethyl methacrylate [DPA] as the second monomer. Star diblock copolymer gelators that were both thermo-responsive and pH-responsive were obtained by the statistical copolymerization of DMA with DPA. Copolymer compositions were assessed by 1H NMR spectroscopy, and the molecular weight distributions of the three-arm star MPC homopolymer precursors were assessed by aqueous gel permeation chromatography. Static light scattering was used to obtain weight-average molecular weights of selected star diblock copolymers and rheological measurements and variable-temperature 1H NMR were used to probe the onset of gelation.
authors.affiliation: Department of Chemistry, Dainton Building, University of Sheffield, Brook Hill, Sheffield S3 7HF, UK.
authors.forename: Yuting
authors.initials: Y
authors.lastname: Li
authors.forename: Yiqing
authors.initials: Y
authors.lastname: Tang
authors.forename: Ravin
authors.initials: R
authors.lastname: Narain
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Lewis
authors.forename: Steven P
authors.initials: SP
authors.lastname: Armes
mesh_terms: D032701:Biomimetics; D002384:Catalysis; D002845:Chromatography; D005782:Gels / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008027:Light; D009682:Magnetic Resonance Spectroscopy; D008689:Methacrylates / Q000737:chemistry*; D009757:Nylons / Q000737:chemistry; D010767:Phosphorylcholine / Q000031:analogs & derivatives / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D012212:Rheology; D013997:Time Factors
chemical_list: D005782:Gels; D008689:Methacrylates; D009757:Nylons; D011108:Polymers; D011109:Polymethacrylic Acids; C519975:monomethoxy-capped poly(propylene oxide) methacrylate; C109846:poly(2-(diethylamino)ethyl methacrylate); C511861:poly(2-(diisopropylamino)ethyl methacrylate); D010767:Phosphorylcholine; C070638:2-methacryloyloxyethyl phosphorylcholine; C049840:2-(dimethylamino)ethyl methacrylate