title: Concentration selective hydration and phase states of hydroxyethyl cellulose (HEC) in aqueous solutions.
abstract: Solution behaviour of hydroxyethyl cellulose (HEC) is reported in the polymer concentration range spanning over two decades (c=0.002-5% (w/v)). The results conclude the following: (i) dilute solution regime prevailed for c<0.2% (w/v), flexible HEC fibres of typical length ≈ 1 μm and persistence length ≈ 10 nm were found here, (ii) for 0.2<c<1% (w/v), a semidilute phase comprising soluble aggregates of hydrated HEC fibrils were observed with the material exhibiting viscoelastic behaviour and (iii) when 1<c<5% (w/v) the solution behaved with melt-like attributes with substantial embedded heterogeneity; viscous to elastic transition was observed in this region. Raman spectral, and DSC data indicated distinctive hydration of HEC fibres in the aforesaid concentration regimes. Cole-Cole plots revealed phase homogeneity and miscibility was limited to concentrations less than ~2% (w/v). For higher polymer concentrations, strong fibre-fibre interactions prevailed and samples became heterogeneous.
authors.affiliation: Polymer and Biophysics Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
authors.forename: Najmul
authors.initials: N
authors.lastname: Arfin
authors.forename: H B
authors.initials: HB
authors.lastname: Bohidar
mesh_terms: D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D004548:Elasticity; D012996:Solutions; D014783:Viscosity; D014867:Water / Q000737:chemistry*
chemical_list: D012996:Solutions; D014867:Water; D002482:Cellulose; C002283:hydroxyethylcellulose