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Synthesis and Characterization of Cellulose Derivatives for Water Repellent Properties

Cotton Chemistry & Utilization Research. Southern Regional Research Center. Synthesis and Characterization of Cellulose Derivatives for Water Repellent Properties. SeChin Chang and Brian Condon Cotton Chemistry and Utilization Research Unit

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Synthesis and Characterization of Cellulose Derivatives for Water Repellent Properties

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  1. Cotton Chemistry & Utilization Research Southern Regional Research Center Synthesis and Characterization of Cellulose Derivatives for Water Repellent Properties SeChin Chang and Brian Condon Cotton Chemistry and Utilization Research Unit USDA-ARS-Southern Regional Research Center, New Orleans, LA Beltwide Cotton Conference, January 11, 2007, New Orleans

  2. Mission of CRIS 6435-41000-094-00DCRIS (Current Research Information Service) Our CRIS is on Value Added Products and Processes from Cotton involves increasing cotton’s consumption by inventing products and processes that demonstrate preferred use of cotton over competing fibers in needed and emerging applications

  3. Talk Outline • Design Criteria • Synthesis • Nitro-benzylated (NB) cotton and cellulose • Amino-benzylated (AB) cotton and cellulose • Characterization • Nitro-benzylated cotton and cellulose • FT-IR spectroscopy • TGA • CP-MAS carbon-13 NMR • Amino-benzylated cotton and cellulose • FT-IR spectroscopy • TGA • CP-MAS carbon-13 NMR • Curing properties with Bis-phenol-A-di-glycidyl-ether (BADGE) • Conclusions

  4. Design criteria • Water repellency, reactivity with epoxide and isocyanates, and the ability to complex main group and transition metals; • Potential uses: adhesives, powder coatings, and composites • Method of cellulose modification: • Synthesis nitro-benzylcellulose (cotton or microcrystalline); • Reduced nitro-group to amine [heterogeneous reduction in ethanol]; or • Substitute nitro-group on aryl ring to H, S-, C-, P- and other groups

  5. Synthesis of nitro-benzyl (NB) cotton & cellulose • Cellulose was subjected to a solvent exchange. • Prepared solution of 2.5g Cellulose, 7g LiCl, and ~100ml DMAc • Added 1.88g DMAP and 10.6g of 4-nitrobenzyl chloride • Heated to 80ºC for 6h under Nitrogen • Work up included: cooling, washing with water • Obtained a brown powder in 70-78% yield • Modified Lit. Method of: N. Joly, R. Granet and P. Krausz, Journal of Carbohydrate Chemistry, Vol. 22, No.1, 47, 2003

  6. FT-IR of cellulose and NB cellulose

  7. Synthesis of amino-benzyl (AB) cotton & cellulose • Suspended 1.0g of Nitro-benzyl cotton or cellulose treated with • 50ml EtOH, 2g Indium metal and saturated ammonium chloride solution 5.0 ml • Heated to 90ºC, overnight, under nitrogen • Work up included: cooling, dilution with water, decanting, washing with water and ether, and drying in vacuo at 40ºC • Obtained a light brown powder in 90-95% yields. • Modified Lit. Method of: Pitts, M.R., Harrison, J.R., and Moody, C.J. J. Chem. Soc., Perkin Trans, 1, 2001, 955-977

  8. FT-IR data of NB & AB cellulose

  9. IR Spectral Interpretation • In the IR spectrum of nitro-benzylcellulose, some peaks for acetone addition oligomers may be present. However, upon reduction of aryl-nitro to amine-group, the other side products were removed.

  10. 13C CP/MAS NMR of NB cotton & NB cellulose 6 4 5 2 1 3 C3, C2, C5 C6 C1 C4 cotton ~106 ~89 80~70 ~64, 62ppm Overlap NB-cotton ~147 134~120 ~114 ~105 ~89,84 80~70 ~62ppm ~54ppm NB-cellulose ~147 ~130 ~124 ~105 ~89,84 80~70 ~62, 54ppm

  11. 13C CP/MAS NMR of NB & AB cotton 6 4 5 2 1 3 NB-cotton ~147 134~120 ~114 ~105 ~89,84 80~70 ~62ppm AB-cotton ~148 140~125 ~116 ~105 ~89,84 80~70 ~62ppm

  12. 13C CP/MAS NMR of NB & AB cellulose 6 4 5 2 1 3 NB-cellulose ~147 ~130 ~124 ~105 ~89,84 80~70 ~62, 54ppm AB-cellulose ~147 140 ~124 117 ~105 ~89,84 80~70 ~62ppm

  13. DSC data for AB cotton & cellulose Cooling Heating AB cellulose AB cotton • Endotherms in first runs: Polymer relaxation and loss of water • NB cotton and cellulose: broad endotherm peak at 30~80C

  14. TGA data for NB & AB cotton cotton NB-cotton AB-cotton

  15. TGA data for NB &AB cellulose NB-cellulose cellulose AB-cellulose

  16. Thermal Degradation Mechanism

  17. Curing reaction of the NB & AB cotton with Bisphenol-A diglycidyl ether (BADGE) + DSC cure The second NH does not react see: Sachinvala et al. J. Polym. Sci.1998, 36, 2397-2413

  18. DSC data for NB & AB cotton with BADGE AB cotton w/BADGE NB cotton w/BADGE • -30 ºC ~ 300 ºC, 20 ºC/min, 3 cycles • Water and/or methanol are known to accelerate decomposition and cure • near 280-300 ºC. Hence, the exothermic spike in the first run. • So why no changes in the second and third heating and cooling runs?

  19. DSC data for NB & AB cellulose with BADGE NB cellulose w/ BADGE AB cellulose w/ BADGE • -30 ºC ~ 300 ºC, 20 ºC/min, 3 cycles • Same spike and no changes in the heating and cooling runs in DSC

  20. Proposed Explanation for Curing without Observable Enthalpy Changes • Aryl Amino groups react with epoxies beyond 280 deg. C; • Hydroxyl group mediated curing does not show heat changes because the enthalpies of bonds made and bonds broken are about the same. That is, delta-H of bonds broken minus bonds formed ~ zero; • DSC is not sensitive to show enthalpy changes in ring strain energy as the epoxy ring opens; • Therefore, changes in enthalpies in DSC heating and cooling runs are not readily seen. • Mechanism and curing of epoxy groups by aryl double bonds is not known, and is under investigation.

  21. AB-cellulose + BADGE TGA of the AB cotton & cellulose with Bis-phenol-A diglycidyl ether (BADGE) AB-cotton + BADGE Char at 500deg.C: AB-cellulose-BADGE > AB-cotton-BADGE because of greater substitution of AB groups in cellulose

  22. Synthesis of Pentafluoro-benzyl cellulose • Cellulose was subjected to a solvent exchange • Prepared solution of 3.0g Cellulose, 6.7g LiCl, and ~100ml DMAc • Added 0.23g DMAP and 1.93g of pentafluorobenzyl bromide • Heated to 80ºC for overnight under nitrogen • Work up and obtained a brown gel solution in high yield • Obtained film, fiber and powder

  23. Conclusions and Future Work • New nitro benzyl (NB) and amino benzyl (AB) cotton and cellulose derivatives were prepared and characterized by FT-IR, 13C CP/MAS NMR, DSC and TGA • Benzylation occurred better in cellulose than in cotton because of ease of swelling the lower MW cellulose 100-1000 DP over cotton > 10,000 DP • Nitro- and amino-benzylated cellulose and cotton cured Bis-phenol A diglycidyl ether (BADGE). No examples of these composites exist in the literature. • TGA studies show high thermal stability cured AB-cellulose-BADGE composites • 1H, 13C NMR, swelling studies, contact angle, and mass characterizations in addition to applications development are on going • Pentafluorobenzyl cellulose will be continue study about physical properties Acknowledgements • Funding from USDA-ARS, CRIS:6435-41000-081-00D • Funding from USDA-ARS, CRIS:6435-41000-094-00D

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