Research Journal of Chemical Sciences ______________________________________________ISSN 2231-606XVol. 4(5), 65-71, May (2014) Res.J. Chem. Sci. International Science Congress Association 65 Gentian Violet Dye Uptake by Graft Copolymers of Vinyl Binary Monomers onto Silk FibreSunil Kumar Rajeev Kr. Sharma and Himanshu3 DIET, Shimla, Himachal Pradesh, INDIA Post Graduate Department of Chemistry, DAV College, Jalandhar, Punjab, INDIA National Institute of Technology, Hamirpur, Himachal Pradesh, INDIA Available online at: www.isca.in, www.isca.me Received 19thMarch2014, revised13thApril 2014, accepted 12thMay 2014Abstract Binary vinyl monomers were grafted onto mulberry silk fibre in aqueous medium by using ceric ammonium nitrate (CAN) as redox initiator. Grafting of binary monomer mixtures of methyl methacrylate (MMA) with butyl acrylate (BA), ethyl acrylate (EA) acrylamide (AAm) and vinyl acetate (VAc) were reported earlier. FTIR, TGA and SEM techniques were used to characterize the graft copolymers. Swelling studies of grafted and ungrafted fibres was done with DMF, water, methanol and n-butanol. Graft copolymers were investigated for dye uptake (gentian violet) photo-calorimetrically at 420 nm. Keywords:Silk fibre, graft copolymer, gentian violet dye. Introduction Some natural occurring as well as synthetic polymers have commercial application1-3. Chemical modification of natural fibres through graft copolymerization is an effective method to incorporate useful properties to the main polymer backbone, and these are useful in many applications in diverse fields4-8. The natural polymers are open to degradation by acids and bases, which limit their applications. The graft copolymerization technique improve the characteristics of polymeric backbones. Grafting of vinyl monomers improve their chemical resistance, thermal resistance and dye uptake behaviour9-17. Silk is one of the most omnipresent natural biopolymers. It finds applications in textile and in surgical applications. Literature survey reveals that various initiators like KMnO–oxalic acid redox initiator18,19, benzoyl peroxide20, CAN21 and potassium peroxydiphosphate-cysteine redox initiator22 were reported for grafting of methyl methacrylate (MMA) onto silk fibres. Grafting of binary vinyl monomer mixture (MMA-co-BA)23, (MMA-co-EA)23, (MMA-co-AAm)24 and (MMA-co-VAc)24. In our earlier work we have reported modification of mulberry silk fibre by grafting of binary vinyl monomer mixtures (MMA-co-BA)23, (MMA-co-EA)23, (MMA-co-AAm)24 and (MMA-co-VAc)24 by initiation with ceric ammonium nitrate. In the present study we have studied the swelling properties of graft copolymers in DMF, water, methanol and -butanol. The graft copolymers were also preliminarily investigated for Gentian violet dye uptake to explore their potential applications in separation technologies, textile industry and biomedical applications. Material and Methods Materials: Mulberry silk (origin Assam, India) was purchased from market. MMA (Merck) was purified by washing with 5% NaOH and subsequent drying over anhydrous NaSO followed by distillation. Butyl acrylate (BA), ethyl acrylate (EA) acrylamide (AAm) and vinyl acetate (VAc) (Merck, US) and ceric ammonium nitrate (CAN) and HNO (S.D. fine Chemicals, India), Gentian violet (Nice Co., India), were used as received. Graft Copolymerization: Graft copolymerization of binary monomer mixtures of MMA with BA, EA, AAm and VAc onto silk were reported in our earlier publications [23,24]. A standard procedure of grafting was adopted and homopolymers were removed from graft copolymer by soxhlet using acetone. The graft copolymers were dried at 50ºC till constant weight was obtained. Swelling and Dyeing behavior: Swelling studies of grafted and ungrafted silk fibres was done with water, methanol, Dimethyl formamide (DMF) and -butanol as per our earlier reported method. Distilled water is used for preparation of 0.1% gentian violet solution for dyeing experiments. Few drops of 10% common salt solution and of acetic acid were added. The fibre was immersed in resultant solution in 1:50 ratio. The adsorption of dye was studied at room temperature (35 ºC). The optical density of solutions were determined by using photo-colorimeter (model 313E, Environment & Scientific Instruments Co. India) at different time intervals of 1, 2, 3, 4 and 5hrs, respectively. The concentration of each solution after dye uptake by the fibre and percent transmittance (%T) was calculated as: Transmittance (T) = × 100 I Research Journal of Chemical Sciences ___________________________________________________________ISSN 2231-606XVol. 4(5), 65-71, May (2014) Res. J. Chem. Sci. International Science Congress Association 66 IConcentration of rejected dye solution = × conc. of standard solution IWhere, Iand I are optical density of rejected dye solution and standard solution, respectively. Results and Discussion Silk contains several functional groups. These groups act as active sites for the grafting of vinyl monomers. Grafting with suitable monomers can improve various physical and chemical properties of backbone polymers. Swelling of Graft Copolymers:The swelling behavior of the graft copolymers was studied to define their end-uses. Swelling of polymeric samples were studied as a function of the nature and P of the graft copolymers as well as nature of the swelling medium. Silk fibre is of hydrophilic nature, hence in different media the swelling of the native fibre was observed to follow the order: HO � MeOH �-BuOH � DMF. In this case the swelling order is explained by the presence of polar groups on the native silk fibre. These groups interact with the water molecules, hence maximum swelling was observed in water. Water can swell the native fibre by deep penetration into the polymer matrix. The same cannot be true for DMF, -Butanol and methanol, as these solvents do not have enough interactions with the functional groups present on the silk fibre. However, in the case of graft copolymers, the maximum swelling of graft copolymers was observed in DMF (figures 1-4). Such trend can be explained by the fact that the grafting of MMA or the comonomers consumed many functional groups on the backbone polymer that otherwise act as active sites for the water absorption. Further, the incorporation of hydrophobic polymers like poly(MMA) or poly(EA) or poly(BA) or poly(VAc) onto a hydrophilic (silk) backbone, also reduced water uptake or swelling. These grafted hydrophobic polymers are more solvated by DMF and to a lesser extent by the other solvents. Swelling behavior of the silk-g-poly(MMA-co-BA) and silk-g-poly(MMA-co-EA) as the function of P followed the order: DMF � n-BuOH � HO � MeOH (figure 1a and 1b). Where as in case of silk-gpoly(MMA-co-AAm) swelling behaviour is in order of DMF � O � MeOH � n-BuOH (figure-3) and in silk-g-poly(MMA-co-VAc) swelling behaviour in different solvent is in order of DMF � HO � n-BuOH � MeOH (figure-4). Dying Studies of Mulberry Silk and Its Graft Copolymers: The dying capability of mulberry silk fibre could also be improved by grafting. The absorption of Gentian violet by the un-grafted and mulberry silk fibres has been depicted in table 1. The dyeing property of silk fibre is declined in grafted hydrophobic binary monomer mixtures, but it increases with increase in Pg in case of silk-g-poly(MMA-co-AAm) and it showed the best result of dye uptake among all graft copolymers. Hence, it has been observed that grafting with the binary mixtures of different vinyl monomers improved swelling in non aqueous solvent, at the same time because of hydrophobic monomers the dying ability of silk fibre get reduced. Thus dye uptake behavior depends upon interactions between the dye and the grafted fibre. Figure-1 Swelling study of silk-g-poly(MMA-co-BA) 20 4060 80 100 120 101520253035404550 % Swelling Percent Grafting MeOH BuOH DMF Water Research Journal of Chemical Sciences ___________________________________________________________ISSN 2231-606XVol. 4(5), 65-71, May (2014) Res. J. Chem. Sci. International Science Congress Association 67 Figure-2 Swelling study of silk-g-poly(MMA-co-EA) Figure-3 Swelling study of silk-g-poly(MMA-co-AAm) 4550 55 606570 75801020304050 % Swelling Percent Grafting Water MeOH BuOH DMF80100120140160180200220 240 260 280300 5 101520253035404550556065 Percent Grafting Water DMF BuOH MeOH % Swelling Research Journal of Chemical Sciences ___________________________________________________________ISSN 2231-606XVol. 4(5), 65-71, May (2014) Res. J. Chem. Sci. International Science Congress Association 68 Figure-4 Swelling study of silk-g-poly(MMA-co-VAc) Table-1 Gentian Violet Dye uptake by the silk and its Graft Copolymers Un-grafted Silk Sr. No [Conc. of test solution (× 10-4 mol/L)] Transmittance (%) Ungrafted silk At different time intervals (min) At different time intervals (min) 60 120 180 240 300 60 120 180 240 300 1 0.0 0.17 [4.76] 0.15 [4.20] 0.15 [4.20] 0.15 [4.20] 0.15 [4.20] 80.95 71.43 71.43 71.43 71.43 Silk--poly (MMA-co-BA)Sr. No [Conc. of test solution (× 10-4 mol/L)] Transmittance (%) At different time intervals (min) At different time intervals (min) 60 120 180 240 300 60 120 180 240 300 1 34.67 0.19 [5.04] 0.18 [5.04] 0.18 [5.04] 0.18 [5.04] 0.18 [5.04] 90.48 85.71 85.71 85.71 85.71 2 41.33 0.17 [4.76] 0.16 [4.48] 0.16 [4.48] 0.16 [4.48] 0.16 [4.48] 80.95 76.19 76.19 76.19 76.19 3 55.03 0. 20 [5.60] 0.18 [5.04] 0.18 [5.04] 0.18 [5.04] 0.18 [5.04] 95.24 85.71 85.71 85.71 85.71 4 98.53 0. 20 [5.60] 0.18 [5.04] 0.18 [5.04] 0.18 [5.04] 0.18 [5.04] 95.24 85.71 85.71 85.71 85.71 5 113.43 0. 20 [5.60] 0.18 [5.04] 0.18 [5.04] 0.18 [5.04] 0.18 [5.04] 95.24 85.71 85.71 85.71 85.71 5060708090100110 102030405060 Percent Grafting MeOH BuOH DMF Water % Swelling Research Journal of Chemical Sciences ___________________________________________________________ISSN 2231-606XVol. 4(5), 65-71, May (2014) Res. J. Chem. Sci. International Science Congress Association 69 Silk--poly (MMA-co-EA)Sr. No [Conc. of test solution (× 10-4 mol/L)] Transmittance (%) At different time intervals (min) At different time intervals (min) 60 120 180 240 300 60 120 180 240 300 1 100.00 0. 20 [5.60] 0.19 [5.32] 0.19 [5.32] 0.19 [5.32] 0.19 [5.32] 95.24 90.48 90.48 90.48 90.48 2 119.03 0. 20 [5.60] 0.18 [5.32] 0.18 [5.32] 0.18 [5.32] 0.18 [5.32] 95.24 85.71 85.71 85.71 85.71 3 133.87 0. 20 [5.60] 0.19 [5.32] 0.19 [5.32] 0.19 [5.32] 0.19 [5.32] 95.24 90.48 90.48 90.48 90.48 4 181.10 0.19 [5.32] 0.18 [5.32] 0.18 [5.32] 0.18 [5.32] 0.18 [5.32] 90.48 85.71 85.71 85.71 85.71 5 231.00 0. 20 [5.60] 0. 18 [5.32] 0. 18 [5.32] 0. 18 [5.32] 0. 18 [5.32] 95.24 85.71 85.71 85.71 85.71 6 241.77 0. 20 [5.60] 0. 18 [5.32] 0. 18 [5.32] 0. 18 [5.32] 0. 18 [5.32] 95.24 85.71 85.71 85.71 85.71 7. 279.96 0. 20 [5.60] 0. 18 [5.32] 0. 18 [5.32] 0. 18 [5.32] 0. 18 [5.32] 95.24 85.71 85.71 85.71 85.71 Silk--poly (MMA-co-AAm)Sr. No [Conc. of test solution (× 10-4 mol/L)] Transmittance (%) At different time intervals (min) At different time intervals (min) 60 120 180 240 300 60 120 180 240 300 1 46.17 0.16 [5.04] 0.15 [4.20] 0.15 [4.20] 0.15 [4.20] 0.15 [4.20] 76.19 71.43 71.43 71.43 71.43 2 50.17 0.16 [5.04] 0.15 [4.20] 0.15 [4.20] 0.15 [4.20] 0.15 [4.20] 76.19 71.43 71.43 71.43 71.43 3 53.03 0.15 [4.20] 0.15 [4.20] 0.14 [3.92] 0.14 [3.92] 0.14 [3.92] 71.43 71.43 66.67 66.67 66.67 4 73.93 0.14 [3.92] 0.14 [3.92] 0.13 [3.64] 0.13 [3.64] 0.13 [3.64] 66.67 66.67 61.90 61.90 61.90 5 78.37 0.14 [3.92] 0.14 [3.92] 0.13 [3.64] 0.13 [3.64] 0.13 [3.64] 66.67 66.67 61.90 61.90 61.90 Silk--poly (MMA-co-VAc)Sr. No [Conc. of test solution (× 10-4 mol/L)] Transmittance (%) At different time intervals (min) At different time intervals (min) 60 120 180 240 300 60 120 180 240 300 1 52.90 0.19 [5.32] 0.18 [5.04] 0.18 [5.04] 0.18 [5.04] 0.18 [5.04] 90.48 85.71 85.71 85.71 85.71 2 66.17 0.19 [5.32] 0.18 [5.04] 0.18 [5.04] 0. 18 [5.04] 0. 18 [5.04] 90.48 85.71 85.71 85.71 85.71 3 76.47 0.19 [5.32] 0. 18 [5.04] 0. 18 [5.04] 0. 18 [5.04] 0. 18 [5.04] 90.48 85.71 85.71 85.71 85.71 4 77.80 0.19 [5.32] 0. 18 [5.04] 0. 18 [5.04] 0. 18 [5.04] 0. 18 [5.04] 90.48 85.71 85.71 85.71 85.71 5 102.67 0.19 [5.32] 0. 18 [5.04] 0. 18 [5.04] 0. 18 [5.04] 0. 18 [5.04] 90.48 85.71 85.71 85.71 85.71 Initial concentration = 5.88 × 10-4 mol/L; wavelength = 420 nm; I = 0.21 Research Journal of Chemical Sciences ____ _ Vol. 4(5), 65-71, May (2014) International Science Congress Association Conclusion The graft copolymerization of the binary mixture of four vinyl monomers separately with methyl methacrylate on to mulberry silk fibre was studied at the pre- determined optimum conditions obtained for the maximum grafting for methyl methacrylate alone. It follows from the results obtained that the nature of the monomers acts as determinant of dying ability as the hydrophobic monomers (BA, EA and VAc) exhibi efficiency than the other monomer i.e. AAm. The dye uptake behavior was also explained by the interaction occurring between the dye and the grafted fibre. Thus, the present study was a successful attempt to understand the role of type of monomers to improve the properties of the native silk fibre those are useful in widening its use- spectrum in textile as well as biomedical applications. Acknowledgement Authors are thankful to Department of Science & Technology (DST), New Delhi for providing instr umentation facility to Department of Chemistry of DAV College, Jalandhar under DST-FIST scheme. References 1. Ghosh Pranab, Das Tapan and Das Moumita, Evaluation of Poly (acrylates) and their copolymer as viscosity modifiers, Res. J. Chem. Sci., 1(3), 18 (2011) 2. Deepshikha and Basu T., The Role of Structure Directing Agents on Chemical Switching Properties of nanostructured conducting polyaniline (NSPANI), Res.J.Chem.Sci., 1(6), 20-29 (2011)3. Manimaran N., Rajendran S, Manivannan M and John Mary S, Corrosion inhibition of carbon steel by polyacrylamide, Res.J.Chem.Sci., 2(3) , 52 4. Kaur, I., Barsola, R., Gupta, A. and Misra, B. N., copolymerization of acrylonitrile and methacrylonitrile onto gelatin by mutual irradiation method Sci.,54, 1131-1139 (1994)5.Kubota, G. and Ujita, S. Reactivity of glycidyl methacrylate- grafted cellulose prepared by means of photografting,J. Appl. Polym. Sci.,56 , 25 6. Chauhan, G. S., Misra, B. N., Kaur, I., Singha, A. S. and Kaith, B. S., Modification of Natural Polymers: Part I Ceric ion initiated graft co- polymerization of methylmthacrylate onto Cannabis fibre, Fibre & Textile Research.,24, 269-275 7. Chauhan, G. S., Bhatt, S. S., Kaur, I., Singha, A. S. and Kaith, B. S., A study in the evaluation of grafting parameters, swelling and thermal behaviour of Rayon and its methylmethacryalate graft co- polymer initiated by ceric ions,J. Polym. Mater., 17, 363- 370 _ _____________________________________________ _ International Science Congress Association The graft copolymerization of the binary mixture of four vinyl monomers separately with methyl methacrylate on to mulberry determined optimum conditions obtained for the maximum grafting for methyl methacrylate alone. It follows from the results obtained that the nature of the monomers acts as determinant of dying ability as the hydrophobic monomers (BA, EA and VAc) exhibi ted less efficiency than the other monomer i.e. AAm. The dye uptake behavior was also explained by the interaction occurring between the dye and the grafted fibre. Thus, the present study was a successful attempt to understand the role of type of to improve the properties of the native silk fibre those spectrum in textile as well as Authors are thankful to Department of Science & Technology umentation facility to Department of Chemistry of DAV College, Jalandhar under Ghosh Pranab, Das Tapan and Das Moumita, Evaluation of Poly (acrylates) and their copolymer as viscosity (2011) Deepshikha and Basu T., The Role of Structure Directing Agents on Chemical Switching Properties of nanostructured conducting polyaniline (NSPANI), Manimaran N., Rajendran S, Manivannan M and John inhibition of carbon steel by , 52 -57 (2012) Kaur, I., Barsola, R., Gupta, A. and Misra, B. N., Graft copolymerization of acrylonitrile and methacrylonitrile onto gelatin by mutual irradiation method J. Appl. Polym. Reactivity of glycidyl - grafted cellulose prepared by means of , 25 -31 (1995) Chauhan, G. S., Misra, B. N., Kaur, I., Singha, A. S. and Kaith, B. 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