Ebringerová, Anna

Heinze, Thomas

Koschella, Andreas

Sroková, Iva

Čížová, Alžběta

English

DSpace at VSB Technical University of Ostrava

, I ti"' b ,t!J prací Vysoké školy báňské- Technické univerzity Ostravačíslo I, rok 2008, ročník LI, řada hutnická článek č. 1396 SURFACE-ACTIVE AND FUNCTIONAL PROPERTIES OF CARBOXYMETHYL ST ARCH OCTENYL-SUCCINATES A. ČÍŽOVÁ 1 *, A. KOSCHELLA2, T. HEINZE2, A. EBRINGEROVÁ3, I. SROKOVÁ 1 1* Faculty of lndustria/ Technologies, Alexander Dubcek University o/ Trenčín, I. Krasku 491/30, 020 OJPúchov, Slovak Republic, cizova@fpt.tnuni.sk 1 Centre o/ Excellence for Polysaccharide Researc/1, Friedrich Schiller University o/ Jena, lnstitute o/ OrganicChemistry and Macromo/ecu/ar Chemistry, Humboldtstr. JO, D-07743 Jena, Germany 1 Centre o/ Excellence of the Slovak Academy of Sciences, Institute o/ Chemistry, Dúbravská cesta 9, 845 38Bratislava, S/ovak Republic ABSTRACT: Carboxymethyl starch octenyl-succinates (OS-CMS) were prepared in dimethylsulfoxide/p-toluenesulfonic acid (DMSO/pTSA) system under classical and microwave heating. Derivatives were characterised by FT-IR spectroscopy. The critical micelle concentration and corresponding maxima! lowering of surface tension of derivatives solutions in water and 0.5 M NaCl were assessed. Surface saturation, minimal area per molecule and further thermodynamic parameters were calculated making evidence, that addition of salt had positive effect on adsorption of molecules at the surface. Octenylsuccinylation leaded to enhanced emulsifying efficiency giving emulsions stable for several hours comparable with commercial standard Tween 20. KEY WORDS: octenylsl_lccinates of carboxymethyl starch, esterification, surface-active properties, m1crowaves l. INTRODUCTIONCarboxymehyl starch (CMS) as a commercially available polysaccharide provides a wide range of applications. It is commonly used in food, paper, textile and pharmaceutical industry [I]. Further modification introducing hydrophobic side groups into hydrophilic CMS backbone leads to water­soluble amphiphilic derivatives, which are able to absorb on the interface [2,3]. Octenyl-succinic anhydride (OSA) has been dealt in various research works [4-8] as an appropriate modification agent for preparation of amphiphilic derivatives due to its dual hydrophobic and hydrophilic character. Moreover, desirable changes in solution properties and viscosity have been observed [9]. The modification of starch with octenyl-succinic andydride was patented by Caldwell and Wurzburg (1953). The esterification was performed in aqueous slurry medium under mild alkaline conditions [IO]. Low OS starch succinates could be also obtained by refluxing in pyridine in the presence of succinic anhydride with or without prior gelatization of starch by heating in 60 % aqueous pyridine and subs'equent distilling the pyridine water azeotrope from the mixture and replacing it with I 00 % pyridine [11, 12]. Another method is based on esterification of starch in dimethylacetamide/LiCI system using pyridine as·a catalyst [13]. In present work, we have concemed with preparation of carboxymethyl starch octenyl-succinates (OS­CMS) in dimethylsulfoxide/p-toluenesulfonic acid (DMSO/pTSA) system according to Vogt et al. (1996) [14], which was presented as a non-derivating solvent system for carboxymethyl cellulose. Surface-active properties of prepared derivatives have been studied and comparison between classical and microwave heating applied was performed. 216 2. MA TERIALSThe carboxymethylated cold-water-soluble potato starch EMSIZE CMS 60 with 28 % amylose content, 11.2 % moisture content and degree of carboxymethylation (DScM) O. I was purchaseď from Emsland-Staerke GmbH (Emlichheim, Germany). Octenyl-succinic anhydride (OSA) of 97 % purity was purchased from Sigma-Aldrich Chemie GmbH (Munich, Germany). Ali solvents were of reagent grade and were used without further purification. 3. METHODS3.1 Esterification of CMS To a stirred suspension of 2 g ( 11.76 mmol) CMS in 25 ml of DMSO, 0.22 g pTSA (O. I mol per mol CMS) was added at 60 °C and stirring was continued for ca. 90 min. The gel-like solution obtained was used in chemical modification without any additional treatment. Then, appropriate amount of OSA was added slowly during I h and the reaction was allowed to proceed for total 24 h at 60 °C. The product was precipitated with acetone, filtered, washed three times with acetone, and vacuum-dried at 60 °C for 24 h before testing. Similarly. suspension of CMS in I O ml of DMSO was pre-heated during I min in modi fied domestic microwave oven Sencor SMW 2220 ať 140 W while stirring. Then, pTSA was added and another minute of microwave irradiation was applied. To a gel-like solution obtained, appropriate amount of OSA was added and the reaction was allowed to proceed for I, 3 or 5 min of microwave irradiation (5 min of stirring between each minute of irradiation). The product was precipitated with acetone, filtered, washed three times, purified for 8 h by Soxhlet extraction with acetone and air-dried before testing. 3.2 Characterization of prepared OS-CMS derivatives Prepared OS-CMS derivatives were characterized by means of FT-IR. Spectra were recorded on a Nicolet Magna 750 spectrometer using 128 scans at a resolution of 4 cm· 1 in KBr pellets. The surface tension of the polysaccharide solution in water and 0.5 M NaCl was determined in the concentration range between O.O 15 and 5 kg/m3 at 25 °C using the Du Noily ring method. OiI-in-water emulsions were prepared by mixing of 50 mg of sample dissolved in 9 ml of distilled water and I ml of paraffin oil dyed with Sudan IV. The laboratory mixer Heidolph DIAX 600 at 22 500 rpm was used. 4. RESUL TS AND DISCUSSIONIn order to find most appropriate way for preparation of OS-CMS water-soluble derivatives, the esterification of CMS with OSA was performed under various· reaction conditions (Tab. I). Tab. I: Results of esterification of carboxymethylstarch (CMS, DScM O. I) with octenylsuccinic anhydride (OSA) at various reaction conditions. Rl'llt'tion t'onclitions Heating Temp. (0C) Time AC'.-)0 I ·O 07 C'.H óO )4 h O R9 AC-3i2 1:0.07 MW 79-120 5 min 0.76 AC-3311 I :0.07 MW 80-100 3 min 0.83 AC-34 I :0.07 MW 90 I min 0.82 AC-35. l:0.07 MW 89-107 5 min 0.77 ·24 h swelling in DMSO withoutpTSA, CH - classical heating, MW - microwave heating217 

Surface-active and functional properties of carboxymethyl starch octenyl-succinates

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Surface-active and functional properties of carboxymethyl starch octenyl-succinates

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