title: Surface and Aggregation Behavior of Pentablock Copolymer PNIPAM7-F127-PNIPAM7 in Aqueous Solutions.
abstract: The triblock Pluronic F127 was modified by introducing poly(N-isopropylacrylamide) (PNIPAM) at both the poly(ethylene oxide) ends, and the pentablock copolymer so-prepared was characterized by gel permeation chromatography and (1)H NMR. The degree of polymerization of NIPAM blocks at the two ends was 7. The solution behavior and microstructure of copolymer aggregates in water and aqueous salt solution were examined and compared with F127 by UV-visible absorption spectroscopy, microdifferential scanning calorimetry, dynamic light scattering (DLS), and small-angle neutron scattering (SANS). The behavior of the pentablock copolymer at the air/water interface was determined by Langmuir film balance. Two lower critical solution temperatures were observed for pentablock copolymer, corresponding to poly(propylene oxide) and PNIPAM blocks, respectively. DLS studies show that micelle size increased with increase in temperature and in the presence of salt. SANS measurements provided temperature-dependent structural evolution of copolymer micelles in water and salt solution. The copolymer displays an isotherm with four classical regions (pancake, mushroom, brush, and condensed state). The study has potential applications in controlled drug delivery due to the tunable phase behavior and biocompatibility of the copolymer.
authors.affiliation: Chemistry Department, V.N.S.G. University , Surat 395007, India.
authors.forename: P
authors.initials: P
authors.lastname: Parekh
authors.affiliation: Graduate School of Engineering, University of Hyogo , 2167 Shosha, Himeji, Hyogo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Ohno
authors.affiliation: Graduate School of Engineering, University of Hyogo , 2167 Shosha, Himeji, Hyogo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Yusa
authors.affiliation: Departamento de Química Física, Facultade de Farmacia, Universidade de Santiago de Compostela , 15782 Santiago de Compostela, Spain.
authors.forename: Emílio V
authors.initials: EV
authors.lastname: Lage
authors.affiliation: Departamento de Química Física, Facultade de Farmacia, Universidade de Santiago de Compostela , 15782 Santiago de Compostela, Spain.
authors.forename: Matilde
authors.initials: M
authors.lastname: Casas
authors.affiliation: Departamento de Química Física, Facultade de Farmacia, Universidade de Santiago de Compostela , 15782 Santiago de Compostela, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Sández-Macho
authors.affiliation: Solid State Physics Division, Bhabha Atomic Research Centre , Mumbai 400085, India.
authors.forename: V K
authors.initials: VK
authors.lastname: Aswal
authors.affiliation: Chemistry Department, V.N.S.G. University , Surat 395007, India.
authors.forename: P
authors.initials: P
authors.lastname: Bahadur