Carbohydrate Research

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Crohydrte Reserch 344 (2009) 851 855 Contents lists ville t ScienceDirect Crohydrte Reserch journl homepge: www.elsevier.

Chngchun Institute of Applied Chemistry Polymer Engineering Lortory, Chngchun 130022, Chin Chngchun University of Technology, School of iologicl Engineering, Chngchun 130022, Chin rticle info strct

1 Crohydrte Reserch 344 (2009) Contents lists ville t ScienceDirect Crohydrte Reserch journl homepge: Preprtion nd chrcteriztion of ctionic corn strch with high degree of sustitution in dioxne THF wter medi Pi-xin Wng, *, Xiu-li Wu, Xue Dong-hu, Xu Kun, Tn Ying, Du Xi-ing, Li Wen-o Chngchun Institute of Applied Chemistry Polymer Engineering Lortory, Chngchun , Chin Chngchun University of Technology, School of iologicl Engineering, Chngchun , Chin rticle info strct Article history: Received 16 Decemer 2008 Received in revised form 12 Ferury 2009 Accepted 18 Ferury 2009 Aville online 28 Ferury 2009 Keywords: Ctionic corn strch High DS Rection medium Structure chrcteriztion Ctionic corn strch derivtives with high degree of sustitution re prepred in lkline solution or in mixed medi of orgnic solvent nd wter with different levels of the ctionic regent, 2,3-epoxypropyltrimethylmmonium chloride. The strch ctioniztion yield is investigted, nd the results indicte tht the degree of sustitution (DS) of the smples depends on the rection conditions nd rection medi. The mximum DS vlues re up to 1.37 in 1,4-dioxne lkline queous solution. Menwhile, the structures of the ctionic strch derivtives re chrcterized y elementl nlyses, FTIR spectroscopy, X-ry diffrction, nd 13 C NMR spectroscopy, s well s y SEM techniques. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction The industril utiliztion of ntive strches is limited ecuse of their inherit nture, such s wter insoluility nd their tendncy to form unstle pstes nd gels. Therefore, strch is usully modified physiclly or chemiclly to chieve prticulr property nd cter to the requirements for tilor-mde products. 1 Etherifiction is very importnt spect of chemicl modifiction. Ctionic strch is ny strch whose free hydroxyls hve een commonly ltered y using the ctionic monomer 2,3-epoxypropyltrimethylmmonium chloride (ETA) or 3-chloro-2-hydroxypropyltrimethyl mmonium chloride (CTA) under wet or dry processes. 2,3 Such modified strches generlly hve physicochemicl properties tht re significntly different from those of the prent strches, such s good soluility nd more functionl groups, therey incresing their usefulness in the pper, textile, oilfield drilling, wstewter tretment, or cosmetic industries. 4 7 Comprehensive investigtions show tht ctionic strch derivtives of low degree of sustitution (DS ) re ville in mny commercil res High-DS ctionic strches hve received much more ttention in recent yers owing to their preferle properties nd potentil pplictions * Corresponding uthor. E-mil ddress: pxwng@cic.jl.cn (P. Wng). Usully, the high-ds ctionic strch is prepred y n queous procedure, s wter fvors the diffusing of the ctionic gent into the strch grnule. However, hydrolysis or other side rections my compete for the etherifiction of strch in the presence of wter. Thus, it is necessry to choose pproprite medi in which wter is prtilly replced in the rection mixture y n ctive solvent. Hn nd Sosulski 14 reported tht the strch ws effectively ctionized in n queous lcoholic solvent. Ayou nd coworkers 15,16 descried series of ctionic strches with low DS (0.05) nd high rection efficiency tht were prepred y rective extrusion process with ETA s the ctioniztion regent nd sodium hydroxide s the ctlyst. Kweon et l. 17 oserved tht the ddition of wter-miscile orgnic solvents to the lkline queous medi could chieve high-ds ctionic strches, nd ethnol ws more effective solvent thn methnol or 2-propnol. A further investigtion y Heinze et l. 18 descried high-ds ctionic derivtives tht were prepred in queous lkline solutions, homogeneously with dimethyl sulfoxide (DMSO), nd heterogeneously with ethnol wter. The results indicted tht the rectivity depended on the rection medi, ut compred with the other process, the modifiction of strch in heterogeneous ethnol wter ws lest effective. In this work, the influence of vried solvent medi on the DS of ctionic strch ws evluted, nd then the ctionic strches with high DS were prepred in dioxne THF wter medium y onestep method. Bsed on these works, the structures of strch derivtives thus otined were chrcterized y elementl nlysis, FTIR spectroscopy, X-ry crystllogrphy, nd 13 C NMR spectroscopy s well s y SEM /$ - see front mtter Ó 2009 Elsevier Ltd. All rights reserved. doi: /j.crres

2 852 P. Wng et l. / Crohydrte Reserch 344 (2009) Results nd discussion 2.1. Effect of sodium hydroxide concentrtion on the DS in queous lkline solutions In this pper, the degree of sustitution of modified strch is cler function of the vrying levels of NOH (Fig. 1). As oserved, the initil increse in the mount of NOH fvorly incresed the DS of the prepred ctionic strches nd rection efficiency (RE). However, further increse in NOH leds to decrese in oth DS nd RE. The DS of smples nd RE re optimum when the concentrtion of NOH is 1 wt %. This phenomenon cn e explined in tht under sic conditions the hydroxy functionl groups of the nhydroglucose units of strch my rect in nucleophilic rection with the etherifiction gent, 19 s in the wellknown Willimson ether synthesis. But t high lkli concentrtion, the ctioniztion gent undergoes hydrolysis rection, which effects n epoxide ring-opening to form the diol product. Oviously, the hydrolysis of the regent should e s low s possile to minimize these side rections. A similr trend ws lso reported y Lwl et l. 20 on croxymethyl cocoym strch Effect of rection temperture nd durtion of rection on the DS in queous lkline solutions Ctionic strch is synthesized y rection of corn strch with ETA t different tempertures nd t vrious durtions of time in queous lkline solutions (Fig. 2). Results clerly indicte tht rection time of 6 h is the optimum for ll smples, nd the highest DS otined is 0.89 t 60 C. It cn e concluded tht the formtion of ctioniztion products previls over the secondry rections within the studied rnge. The DS of smples ws nerly constnt with increse in rection time when the rection temperture ws low (50 C). However, upon exceeding this temperture (60 nd 70 C), there ws n increse in the deetherifiction rection tht cused the DS to decrese Comprison of different orgnic medi The influences of different solvents on the DS of ctionic strches prepred in orgnic solvent sodium hydroxide wter re investigted in our work, nd the results re summrized in Tle 1. Compred to the results in queous medi, the smples DS Concentrtion of NOH in wter [%] Figure 1. DS of ctionic corn strch depending on the mount of NOH (ETA/ AGU = 2:1 mol/mol, 60 C, 6 h) RE (%) DS Figure 2. DS of ctionic strches prepred t different rection tempertures nd durtion of rection (NOH concentrtion 1.0%; ETA/AGU = 2:1 mol/mol). prepred in orgnic medi hve not shown ny evidence of geltiniztion when smples re gin dissolved. The dt in Tle 1 show n ovious reltionship etween the DS nd the kind of orgnic solvent. When the molr rtio of ETA/ AGU is 4, the highest DS vlues re 1.26, 1.19, nd 0.65 for the rection in dioxne, THF, nd ethnol, respectively. It is evident tht dioxne nd THF pper to enhnce good selectivity for the rection tht fvors strch ctioniztion. In comprison with other works, Jie et l. 21 reported tht orgnic solvents oviously hd n effect on rection efficiency, nd 2-propnol nd tert-utnol were etter solvents thn methnol nd ethnol for the croxymethyltion process of cssv strch. However, the rection efficiency in this prt of work cnnot e mesured ecuse the level of ETA is fr more thn the norml level (when the molr rtio of ETA/AGU exceeds 3, the rection efficiency cnnot e mesured). Generlly, good orgnic solvent for the rection should e one hving high misciility with wter to void phse seprtion, s well s the ility to dissolve the etherifying gents nd offer stiliztion to the process. In ddition, wter lso plys significnt role in iding the diffusion nd dsorption of etherifying gents s well s fcilitting the swelling of the strch during the ctioniztion process. At the sme time, wter lso cn ffect the distriution of the vrious components etween the ulk liquid phse nd the strch prticles. A prior investigtion 22 hs shown tht NOH precipittes in mixture of ETA nd NOH tht hs shortge of wter. Thus, it is necessry tht prticulr quntity of wter e used for NOH hydrtion in the rection mixture. Typiclly, in our work the rtio of wter to orgnic solvent is 1:1 (v/v). T/h Tle 1 The effect of the rection of strch with ETA in different medi on the DS Smple no. Medi ETA/AGU molr rtio DS 1 Ethnol/wter Ethnol/wter Ethnol/wter Dioxne/wter Dioxne/wter Dioxne/wter Dioxne/wter THF/wter THF/wter

3 P. Wng et l. / Crohydrte Reserch 344 (2009) Asornce (%) d c Wvenumer (cm -1 ) 2.4. FTIR spectroscopy of ctionic strches 3017 Figure 3. () FTIR spectr of ntive strch () ETA nd ctionic strch with DS of (c) 0.89, nd (d) To determine the structure of ctionic strches, FTIR spectr re mesured. Spectr of ntive strch, ETA, nd ctionic strches re shown in Figure 3. In the spectrum of ntive strch (Fig. 3), the chrcteristic sorptions tht pper t 1154, 1121, nd 1017 cm 1 re ttriuted to the C O ond-stretching virtion of the nhydroglucose units. 23 The nd t 2926 cm 1 is chrcteristic of the C H stretching virtion. Menwhile, n extremely rod nd resulting from virtion of the hydroxyl groups (O H) ppers t 3414 cm 1. In the cse of ETA (Fig. 3), the rod nd t 3392 cm 1 is for the O H stretching virtion of wter molecules tht remin fter drying. The nds t 3016 nd 1481 cm 1 re ssigned to the C H nd C N stretching virtions, respectively. A strong nd t 1265 cm 1 is due to the epoxy ether. Figure 3c nd d shows the FTIR spectr of ctionic strches of different DS vlues. Ctionic strch nd ntive strch hve similr profiles. Besides the chrcteristic strch ckone peks, dditionl dsorption nds for the quternry mmonium groups pper t 2932 cm 1 (C H) nd 1493 cm 1 (C N). In ddition, with n incresing DS (Fig. 3c nd d), the intensity of peks t 1493 cm 1 is grdully strengthened, which is cler evidence for the incorportion of ctionic moiety onto the ckone of the strch. These results re similr to those reported erlier C NMR spectroscopy of ctionic strch The 13 C NMR spectrum of ntive strch in Figure 4 shows the correltion pek of ech cron of the nhydroglucose unit. Gong et l. reported the ssignment of the 13 C shifts of the glycopyrnn units of the ntive strch. 24 In ctionic strch (Fig. 4), the prominent pek for C-10 t 53.9 ppm is ttriuted to the CH 3 cron of the ctionic group. The peks t 99.1 nd 96.0 ppm re ssigned to C-1. As oserved, two peks pper here ecuse of the ctioniztion sttus of C-2. In this sense, two different environments could occur for C-1, depending on whether or not there is ctioniztion sustitution t C-2. The result here suggests tht ctioniztion sustitution t C-2 cuses split of C-1. Unsustituted nd sustituted C-2, C-3, nd C-5 pper etween 70.6 nd 76.0 ppm. The signl t 79.9 ppm is ssigned to C-4, while C-6 ppers t 60.0 ppm. The signls t 72.4, 67.6, nd 64.8 ppm re elieved to elong to the crons of C-7, C-9, nd C-8, respectively. The pek ssignments for the CH 2 groups t C-6, C-7, nd C-9 hve negtive intensities nd cn e esily distinguished from the CH groups y DEPT-135 experiment, fct tht hs een verified y Heinze et l Morphology of ntive strch nd ctionic strch Scnning electron microscopy (SEM) is used to study the chnges in morphology of the ntive nd modified strch grnules. The ntive corn strch grnules (Fig. 5) re round nd polygonl in shpe with well-defined integrity, wheres the ctioniztion process considerly chnges the strch grnule morphology. When the DS of ctionic strch is low, the ctionic regent penetrtes the interior of the strch molecule, nd the strch grnules re mrkedly enlrged nd egin to disintegrte (Fig. 5). With further increse in DS, the surfces of the strch grnules completely disintegrte, nd their edges drsticlly lose C 3 C 2,5 C 6 C 1 C 4 C 2,3,5,7 C 9 C 8 C6 C 10 6 OR 4 5 O RO O O CH N CH 3 Cl OH CH 3 10 C ' C 4 C 1 1 Ä (ppm) Figure C NMR spectr of () ntive strch nd () ctionic strch of DS 0.89 (R = H or ctionic group ccording to DS).

854 P. Wng et l. / Crohydrte Reserch 344 (2009) 851 855 Figure 5. SEM pictures of strch grnules: () ntive strch 1000; () DS 0.54 ctionic strch 200; (c) DS 1.35 ctionic strch 200. definition (Fig. 4c).

4 854 P. Wng et l. / Crohydrte Reserch 344 (2009) Figure 5. SEM pictures of strch grnules: () ntive strch 1000; () DS 0.54 ctionic strch 200; (c) DS 1.35 ctionic strch 200. definition (Fig. 4c). Apprently, ctioniztion destroys the structure of the corn grnule nd reduces hydrogen onding. Comined, these fctors fcilitte rpid wter uptke to the point tht even the higher DS ctionic strch will dissolve in cold wter X-ry diffrction studies X-ry diffrction mesurements re performed to investigte the chnge of the crystllinity of strch, nd the results re presented in Figure 6. Ntive corn strch exhiits n A-type crystllinity pttern. 25,26 The strong reflections (2h) re pproximte to 15 nd 23, nd n unresolved doulet ppers t 17 nd 18 (Fig. 6). It is noted tht the crystllinity pttern of the strches cn e dmged due to geltion, nd these chrcteristic ptterns cn e prtly recovered during the precipittion nd drying of smples. However, the dmge to the crystllinity pttern of the strches due to ctioniztion cn hrdly e recovered. In our investigtion, fter ctioniztion, the A-type crystllinity pttern of the strches is slightly wekened with DS of 0.27 in ethnol wter (Fig. 6). This result suggests tht the crystllinity pttern of strch is prtly dmged. With n increse in DS, the smll peks dispper nd merge into single, rod, rounded pek tht indictes the disppernce of the crystllinity pttern (Fig. 6c nd d). This loss in crystllinity cn e ttriuted to the effect of the lkline environment nd wter during the modifiction. This opens up potentil utiliztion of ctionic strches s flocculnts, ecuse morphous grnules would enhnce their ility to form colloidl or true solution in cold wter. These soluility chrcteristics re very importnt from prcticl point of view, ecuse in wstewter tretment plnts flocculnts re often dissolved in cold wter. Intensity d c θ ( ) Figure 6. X-ry diffrction ptterns of () ntive strch nd ctionic strch with DS of () 0.27, (c) 0.54, nd (d) Conclusions The synthesis nd chrcteriztion of ctionic derivtives of corn strch re presented in this pper. A ctionic strch with high DS cn e prepred with ETA in suspension of strch in wter or in mixture of n orgnic solvent in n queous lkline solution. Moreover, vrious rection prmeters nd synthesis conditions were investigted, nd the results indicte tht the procedure using 1,4-dioxne with n lkline queous solution s co-solvent is preferred. The highest DS otined ws out 1.37, in which rection temperture of 60 C nd rection time of 6 h re employed. From the ove-mentioned experiment, it cn e concluded tht on the ckone of strch ctionic group is incorported, s confirmed y FTIR nd 13 C NMR spectroscopy. SEM nd X-ry diffrction ptterns oviously show tht ctioniztion dmges the strch grnules nd the mount of morphism increses during the process. 4. Experimentl 4.1. Mterils Corn strch ws otined from Chngchun Dcheng Industril Group Co., Ltd (Chin) nd ws dried t 100 C under vcuum. 2,3-Epoxypropyltrimethylmmonium chloride (ETA) ws purchsed from Shndong Guofeng Fine Chemicl Co., Ltd (Chin). Sodium hydroxide, ethnol, 1,4-dioxne, nd tetrhydrofurn (THF) used in the study were of nlyticl grde Preprtion of ctionic strch Ctioniztion of strch in queous lkline solutions Strch (10.0 g) ws suspended in 50 ml of vrious concentrtions of q NOH solution with gittion t 60 C for 1 h. Then, the ctioniztion regent ETA (70 wt % q solution) ws dded dropwise. The rtio of ETA to nhydroglucose unit (AGU) ws vried from 1 to 4 (mol/mol) in order to otin strch derivtives with different DS vlues. After stirring for 4 8 h t given temperture, the solution ws cooled to room temperture, nd the ph ws djusted to 7 using 0.1 M HOAc. The product ws isolted y precipittion into EtOH nd purified y dilysis ginst wter, followed y freeze drying Ctioniztion of strch in n orgnic solvent NOH wter mixture Strch (10.0 g) ws suspended in 50 ml of 1:1 (v/v) orgnic solvent nd q NOH solution contining 0.5 g NOH t 60 C for 1 h. Susequently, the ctioniztion gent ETA (ETA/AGU = 1 8 mol/ mol) ws dded dropwise to the suspension, nd the mixture ws stirred for 6 h t 60 C. Agin, the smples were neutrlized, precipitted, purified, nd freeze-dried s for the queous lkline procedure in Section

5 P. Wng et l. / Crohydrte Reserch 344 (2009) Mesurements FTIR nlysis ws performed using Bruker Vertex 70 FTIR spectrometer (Germny). The smples were mixed with KBr. FTIR spectr were recorded with resolution of 4 cm 1 nd 32 scns nd wve numer rnge of cm 1. The 13 C NMR spectr were cquired y Bruker AV 400 MHz Fourier-trnsform spectrometer (Germny). Smples were dissolved in D 2 Ot80 C, nd the nlysis ws crried out t 25 C. X-ry diffrction ws otined from Philips PW1710 sed diffrctometer, conventionl copper trget X-ry tue set to 40 kv nd 30 ma. The X-ry source ws Cu K filtered rdition. Dt were collected in the 2h rnge of (h eing the ngle of diffrction) with step width of 0.1. Surfce morphologies of grnulr chrcteristics of strch nd derivtive prticles were nlyzed using scnning electronic microscopy (SEM) with JMS-5600 Electron Microscope (JEOL). The freeze-dried strch nd derivtive powders were used for SEM nlysis. SEM imges were collected from gold-sputtered sustrte surfces. The nitrogen elements of ctionic strches were estimted y elementl nlysis (Vrio EL III, Germny). DS ws clculted ccording to the nitrogen content (N%) using the following eqution: 162N% DS ¼ :5N% : 4.4. Sttistics All mesurements were mde in triplicte. Anlysis of vrince (ANOVA) ws performed using the Duncn s multiple rnge tests to compre tretments mens. Significnce ws defined t P < Acknowledgment The finncil support from the Ntionl Nturl Science Foundtion of Chin (Grnt No ) is grtefully cknowledged. References 1. Fleche, G. Chemicl Modifiction nd Degrdtion of Strch. In Strch Conversion Technology; Vn Beynum, G. M., Roels, J. A., Eds.; Mrcel Dekker: New York, Hellvig, G.; Bischoff, D.; Ruo, A. Strch/Stärke 1992, 44, Khlil, M. I.; Frg, S.; Hshem, A. Strch/Stärke 1993, 45, Tnk, H.; Swerin, A. Tppi J. 1993, 76, Peiffer. U.S. Ptent , Pl, S.; Ml, D.; Singh, R. P. Crohydr. Polym. 2005, 59, Wurzurg, O. B. Introduction. In Modified Strches: Properties nd Uses; Wurzurg, O. B., Ed.; CRC Press: Boc Rton, Rdost, S.; Vorwerg, W.; Eert, A. Strch/Stärke 2004, 56, Jouko, K. U.S. APP , Khlil, M. I.; Frg, S. Strch/Stärke 1998, 50, Mert, J.; Stenius, P.; Pirttinen, E. J. Disp. Sci. Technol. 1999, 20, Mert, J.; Stenius, P. Colloids Surf. A 1999, 149, Zhng, M.; Ju, B. Z.; Zhng, S. F.; M, W.; Yng, J. Z. Crohydr. Polym. 2007, 69, Hn, H. L.; Sosulski, F. W. Strch/Stärke 1998, 50, Ayou, A.; Berzin, F.; Tighzert, L.; Blird, C. Strch/Stärke 2004, 56, Ayou, A.; Blird, C. Strch/Stärke 2003, 55, Kweon, M. R.; Sosulski, F. W.; Bhirud, P. R. Strch/Stärke 1997, 49, Heinze, T.; Hck, V.; Rensing, S. Strch/Stärke 2004, 56, Wu, X. L.; Xue, D. H.; Xu, K.; Du, X. B.; Zhng, W. D.; Song, C. L.; Wng, P. X. Fine Chemicls 2007, 24, Lwl, O. S.; Lechner, M. D.; Hrtmnn, B.; Kulicke, W. M. Strch/Stärke 2007, 59, Jie, Y.; Chen, W.-r.; Mnurung, R. M.; Gnzerld, K. J.; Heeres, H. J. Strch/Stärke 2004, 56, Bendoritiene, J.; Kvliuskite, R.; Klimviciute, R.; Zemititis, A. Strch/ Stärke 2006, 58, Fng, J. M.; Fowler, P. A.; Syers, C.; Willims, A. P. Crohydr. Polym. 2004, 55, Gong, Q.; Wng, L.-Q.; Tu, K. Crohydr. Polym. 2006, 64, Puchongkvrin, H.; Bergthller, W. Strch/Stärke 2003, 55, Shrgren, R. L.; Viswnthn, A. Strch/Stärke 2000, 52,

Colorimetric detection and separation of chiral tyrosine. based on N-acetyl-L-cysteine modified gold. nanoparticles

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