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Functional modification of cellulose for controlled release systems

Functional modification of cellulose for controlled release systems. Alena Šišková, Anita Eckstein Andicsová Polymer Institute, Slovak Academy of Sciences, Dúbravská cesta 9, 845 41 Bratislava, Slovakia. COST Action FP1205 Meeting, 13.-14. April 2016, Boras, Sweden. Outline. Motivation

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Functional modification of cellulose for controlled release systems

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  1. Functional modification of cellulose for controlled release systems Alena Šišková, Anita Eckstein Andicsová Polymer Institute, Slovak Academy of Sciences, Dúbravská cesta 9, 845 41 Bratislava, Slovakia COST Action FP1205 Meeting, 13.-14. April 2016, Boras, Sweden.

  2. Outline • Motivation • Objectives • Materials • Chemical Modifications – „click“ reaction • Results • Processes to reach the objectives • Summary

  3. Motivation Due to the increasing contamination of water and soil by pesticides/herbicides there is a growing requirement for systems of controlled release of agrochemicals. The pesticides are immobilized on the carrier, this reduces their mobility and its leaching into the water and the soil. The use of pesticides in traditional forms such as granules, powders, emulsions - ineffective! Films / fibrous materials formulation seem to be good choice: Advantages: – prolonged duration of action of the active substance – reduction of the loss of substancerelated to weather conditions – reduction environmental pollution - reduction of the handling cost

  4. Objectives • The main objective of this study is to design, prepare and characterizethe material suitable for controlled release systems for potential use in agriculture. • This study isinvolving • the preparation of films/ fibrous mats as suitable polymer carrier for plantprotectionchemiclas. • immobilization of that plant protection chemicals. (Clickreaction) • Tests of effectivity of suchmaterials by hydrolysis and in therealconditions – in thesoil. • Characterization of prepared material.

  5. Materials From natural polymers the cellulose is the most abundant material on the earth and also in the intended processes the secondary raw cellulosic material from the waste can be used. Cellulose used in this study: Microcrystalline cellulose from Alfa Aesar with degree of polymerization < 350

  6. Herbicides used in agriculture

  7. Herbicide - Metribuzine ALKYLATION of Metribuzin: Metribuzin Alkylated Metribuzin K2CO3, DMF 24 h, 45oC Br

  8. Chemical Modification I. • Tosylation to improvethe –OH groupactivity, by TosCl in thepresent of 1% pyridine • Functionalgroups are substituted by azid (NaN3 in water) • Specific „click“ reaction – Cu (I) – catalyzedazide – alkynecycloaddition. (coppersulfate and ascorbicacid are present as activators)

  9. Chemical modification of cellulose II. 1. 3. Cellulose films 2. Cellulose solution Cellulose fibers

  10. Experiment I.- Preparation of cellulose film Preparation of solutions: 3 wt.% of microcrystalline cellulose in ionic liquid - 1-Buthyl-3-methylimidazolium chloride, BMIM Cl - Stirring at 80oC aprox. during 8 hours Preparation of films: - Casting to coagulation bath: water/MeOH - multiple washing of material Drying in the at 50oC aprox. 2 hours XRD: X-Ray diffraction (XRD) studies were carried out using a Xpert Pro. The XRD patterns were recorded in the 2Θ range of 10-60o with step width 0,03o and step time 19,99 sec using Cu radiation (λ = 1,5406 Å) Coagulation: water/MeOH, drying in ambient temperature

  11. Experiment II. - Preparation of cellulose fibers mats Electrospinning • Preparation of 10 wt.% cellulosic solution • Cellulose dissolved in 1-Butyl-3-methylimidazolium Chloride, [BMIM] Cl • Concentration: 20 wt.% • Temperature: 120oC • Time of stirring:aprox. 3 hs. • DMF wasadded to obtain 10wt.% solution High Voltage, Power Supply Stock solution Spinneret Pump Liquid grounded collector Experimental Equipment Electrospinning conditions: Flow rate: 0,30 mL/h Voltage: 20 kV Working distance: 3 cm Ambient temperature: 24,5± 0,5o C Average diameter: 4,04 ± 2,43 μm The morphology and the diameters of fiber samples were observed by the scanning electron microscopy (SEM/FIB ZEISS AURIGA Compact)

  12. Results – Characterization of modified substrate FTIR-ATR - monitoring of absorption bandschanges of functional groups 1640 cm-1 During cycloaddition the 1,2,3 – triazoles are forming, which are susceptible for enzymatic degradation FTIR: NaN3, cellulose with NaN3, Metribuzin, Modifcated cellulose

  13. Summary • We preparedcellulose substrate by castingfrom IL into the coagulation bath and alsothefibrousmats by electrospinning. • Substratesweremodified by chemicalmodification by specific „clickreaction“ on surface of substrate. • Informationaboutchemical modification effectivity was obtained by FTIR. • Chemicalmodificationwassuccessful – change in absorptionbands of presentfunctionalities – FTIR-ATR

  14. Thank you for your kind attention Acknowledgement: Thisresearchwassupportedby the projects: VEGA 2-0142-14 and MVTS/COST FP1205 project. I wouldlike to thank my co-worker: Anita Eckstein and Piotr Rychter. COST Action FP1205 Meeting, 13.-14. April 2016, Boras, Sweden.

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