Materials Science and Engineering B 182 (2014) 6–13 Contents lists available at ScienceDirect Materials Science and Engineering B jou rn al h om epa ge: www.elsevier.com/locate/mseb Electrical transport study of potato starch-based electrolyte system-II Tuhina Tiwari a , Manindra Kumar a , Neelam Srivastava a,∗ , P.C. Srivastava b a Department of Physics (Mahila Mahavidyalay), Banaras Hindu University, Varanasi, India b Department of Physics, Banaras Hindu University, Varanasi, India a r t i c l e i n f o Article history: Received 20 June 2013 Received in revised form 23 October 2013 Accepted 13 November 2013 Available online 28 November 2013 Keywords: Polymers Dielectric properties Electrical conductivity Electrical properties a b s t r a c t Glutaraldehyde (GA) crosslinked potato starch, after mixing with sodium iodide (NaI), resulted in elec- trolyte film having conductivity () ∼ 10 -3 S/cm and ionic transference number (t ion ) ≥ 0.99. Out of two preparation mediums, namely methanol and acetone, methanol based electrolyte system seems to be better. Super-linear power law (SLPL) phenomenon is observed in MHz frequency range and both lat- tice site potential and coulomb cage potential due to neighboring mobile charge carriers seems to be responsible for existence of SLPL, and variation of power law exponent ‘n’ with salt concentration. These ion dynamics results are supported by dielectric data also. Estimated number of charge carriers ‘N’ and mobility ‘’ are discussed with reference to different variants (medium of preparation, plasticizer, and salt content). Material’s conductivity strongly depends on humidity. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Liquid electrolytes stands ahead of their solid counterpart from conductivity point of view but mechanical problem comes in package, which forced the scientist to look for alternative electrolyte systems having physique of solids but conductivity comparable to liquids. Polymer electrolytes fit to these require- ments. Hence solid polymer electrolytes emerged as important class of materials and now they are significantly contributing in development of electrochemical devices [1–5]. Though synthetic polymers are being used in many commercial devices but increas- ing environment awareness has compelled scientists to search for possible biodegradable alternates to reduce chemical junk. Natural polymers are being successfully tried for the purpose, especially starch, chitin, cellulose, chitosan, gelatin, etc. [6–10]. Starch came out as most popular, renewable and biodegradable polymer host, for polymer salt complex electrolytes, due to its rich variety and abundance in nature [11–15]. Starch modified by crosslinking, plasticization and gelatinization has shown better properties in comparison to native starch [16]. Commonly used starches, for electrochemical applications, are potato [17,18], corn [11,12], cassava [19], etc. Since all the starches are made up of amylose & amylopectin, many electrochemists preferred not to specify the name of starch [20–22] but carbohydrate related lit- erature indicates that they do differ, depending upon their origin. Potato starch is reported to have minimum ghost microstruc- ture [23], adding to its popularity. Potato starch based, many ∗ Corresponding author. Tel.: +91 05426701066; mob.: +91 9415424782. E-mail address: neelamsrivastava bhu@yahoo.co.in (N. Srivastava). electrochemical application (including patents) reports can be found in literature [17,18,24]. Because of its promising electro- chemical characteristics it demands special attention and detailed analysis. In our previous study, fungal free, good conducting electrolyte films were obtained by crosslinking potato starch with GA [25], hence in present study also GA crosslinked starch is used as host material. We started with water as preparation medium but a strong retrogradation effect was observed; hence other mediums are investigated. Present paper comprehensively reports system- atic analysis, to understand the effect of medium (of preparation) and addition of polyethylene glycol, on electrical properties of ‘GA crosslinked potato starch + NaI electrolyte’, along with salt concen- tration effect (with methanol as preparation medium). Anticipating the effect of protic/aprotic nature of medium on electrolytic behav- ior, Starch salt complexes using different polar mediums, namely protic (methanol) & aprotic (acetone), were prepared and charac- terized. 2. Experimental 2.1. Sample preparation Potato starch (PS) (C 6 H 10 O 5 ) n [Loba Chemie], Sodium Iodide (NaI) [Gr Loba Chemie], Glutaraldehyde (GA) (C 5 H 8 O 2 ) [Loba Chemie], Polyethylene glycol 300 (PEG) [Loba Chemie], Methanol (M) [RFCL Limited], Acetone (A) [Fisher Scientific] were used for study. Samples having different mediums (methanol/acetone) had been prepared using solution cast techniques at 30 ◦ C. 10 ml methanol/10 ml acetone with 1 g of starch was used for mate- rial preparation. For 1 g of starch, ∼20% of PEG (0.17 g), 0.2 g NaI 0921-5107/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.mseb.2013.11.010