title: Internal structure and thermo-viscoelastic properties of agar ionogels.
abstract: Ionic liquids (IL) can alter the physical properties of agar hydrogels. Rheology studies show that gels with wide range of storage moduli (gel strength) G0 values ranging from 1 to 20 KPa could be made in imidazolium based IL solutions where the IL concentration may not exceed 5% (w/v). Gelation and gel melting temperatures (tgel and Tm) could be altered by as much as ≈ 10 °C. Small angle neutron scattering studies revealed the presence of fibre bundles of agar double helices having typical length of 120 nm that increased to ≈ 180 nm under favorable conditions. These structures gain flexibility from the cladding of the agar bundles by IL molecules which in turn caused partial charge neutralization of its surface. Raman spectroscopy revealed differential hydration of these bundles. It was found that IL molecules with longer alkyl chain (more hydrophobic) altered the gel homogeneity, and changed its thermal and mechanical properties significantly. Therefore, customization of agar hydrogels in green solvent medium (IL solutions) widens the scope of its application potential that may include sensing.
authors.affiliation: School of Physical Sciences, Jawaharlal Nehru University, New Delhi, India; Special Centre for Nanosciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Anshu
authors.initials: A
authors.lastname: Sharma
authors.affiliation: Special Centre for Nanosciences, Jawaharlal Nehru University, New Delhi, India; Inter University Accelerator Centre (IUAC), New Delhi 110067, India. Electronic address: kamla.jnu@gmail.com.
authors.forename: Kamla
authors.initials: K
authors.lastname: Rawat
authors.affiliation: Special Centre for Nanosciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Pratima R
authors.initials: PR
authors.lastname: Solanki
authors.affiliation: Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai, India.
authors.forename: V K
authors.initials: VK
authors.lastname: Aswal
authors.affiliation: Laboratory for Neutron Scattering, Paul Scherrer Institute, Villigen, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Kohlbrecher
authors.affiliation: School of Physical Sciences, Jawaharlal Nehru University, New Delhi, India; Special Centre for Nanosciences, Jawaharlal Nehru University, New Delhi, India. Electronic address: bohi0700@mail.jnu.ac.in.
authors.forename: H B
authors.initials: HB
authors.lastname: Bohidar
mesh_terms: D000362:Agar / Q000737:chemistry*; D004548:Elasticity; D005782:Gels; D052578:Ionic Liquids / Q000737:chemistry*; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation; D012212:Rheology; D044366:Transition Temperature; D014783:Viscosity
chemical_list: D005782:Gels; D052578:Ionic Liquids; D000362:Agar
keywords: Agar ionogels; Hydration layer; Ionic liquid; Neutron scattering; Raman spectra; Rheology