Kai Zhang, Uni Göttingen

Transcription

1 Im Kleinen liegt Großes Nanostrukturierte funktionelle Materialien aus Holzkomponenten Jr.-Prof. Dr. Kai Zhang JP Holztechnologie & Holzchemie Georg-August-Universität Göttingen NHN Tagung, Jun

2 53-metre dormitory at the University of British Columbia in Vancouver

3 paper energy Construction materials Wood textile Many others 3

4 Hierarchical structure in plant cell wall Taiz and Ziegler 1993 Scheller 2010 Annu Rec Plant Biol Pea primary cell wall Talbott and Ray, 1992 Plant Physioll Secondary cell wall Bidlack et al., 1992 Proc Okla Acad Sci 4

5 Nanocellulose 5

6 Holzchemie und Cellulosechemie 6

7 Funktionelle Materialien Surface coating (e.g. super/hydrophobization) Responsive, self-standing films gels nanoparticles / microparticles (1) The Journal of Physical Chemistry C 2014, 118, (2) Angewandte Chemie Int Edition, 2014, (3) Chemistry A European Journal 2015, 21, 1-8 (4) Physical Chemistry Chemical Physics, 2014, (5) Advanced Functional Materials, 2015,, 25, (6) Nanoscale, 2016, 78, 648.

8 Synthesis of crystalline nanocellulose Native Cellulose Cellulose at nanoscale and molecular level Moon et al., 2011 Chem Soc Rev chemically / mechanically Taiz and Ziegler 1993 Microfluidizer (microfluidics incorp.) Nano/Microfibrillated cellulose (NFC) Cellulose nanocrystals (CNC) Cellulose nanowhiskers (CNW) etc.

9 Heterogeneous catalysis: Dirhodium (II) complex on CNC Synthesis: immbolization of dirhodium complex onto CNC surface Liu, Plog, Groszewicz, Zhao, Xu, Breitzke, Stark, Hoffmann, Gutmann,* Zhang,* Buntkowsky.* Chemistry A European Journal 2015, 21, 1-8

10 Cellulose nanocrystals (CNC) as substrate for biomacromolecules, e.g enzymes. Potential carrier systems Accessible surface The amount of potential guest compounds at µmol level Christina Uth, Stefan Zielonka, Sebastian Hörner, Nicolas Rasche, Andreas Plog, Hannes Orelma, Olga Avrutina, Kai Zhang,* and Harald Kolmar* Angewandte Chemie Int Edition, 2014,

11 Example: CNC with immobilized galactose oxidase with maintained activity

12 Functional materials based on crystalline nanocellulose Responsive CNC via surface-immobilization of stimuli-responsive groups e.g. with stimuli-responsive rhodamine spiroamide Potentially for biomedical imaging and detection Low amount of RhB spiroamide: 0.2±0.01 mmol/g L. Zhao, W. Li, A. Plog, Y. Xu, G. Buntkowsky, T. Gutmann,* K. Zhang* Physical Chemistry Chemical Physics, 2014,

13 Pre-organized cellulose nanocrystal crosslinker for robust hydrogel Huang, Wang, Rehfeldt, Zhang. Macromolecular Rapid Communication, 2017, 38,

14 1% CNC as prepared, tensile trial

15 Spheric crystalline cellulose nanoparticles Heterogeneous esterification using intermediate amount of stearoyl chloride Synthesis of surface-stearoylated cellulose nanoparticles (SS-CNPs) 3 mol stearoyl chloride per mol AGU of cellulose Removal of soluble product and bigger fragments by centrifugation Y. Wang, L. Heim, Y. Xu, G. Buntkowsky, K. Zhang* Advanced Functional Materials, 2015,, 25,

16 Properties Dynamic light scattering particle size The suspensions of SS-CNPs in organic solvents Stable and (semi)transparent Re-suspendable after drying! 5 mg/ml

17 Gelation behaviour of suspensions Changing temperature: thermo-reversible gelation 5 mg/ml in THF Changing concentration: gelation at RT Elastic G a d viscous G odulus as a fu ctio of oscillatory shear frequency 17

18 Application of crystalline cellulose nanoparticles: Self-standing films - Solvent casting Self-standing, flexible, transparent film - Solvent-switchable surface wettability of SS-CNPs film 18

19 Solvent-responsive shape memory Good shape fixation by heating or solvent treatment; One-way solvent responsive shape-memory behavior; 19

20 Proposed mechanism Core Contact Surface Core Core Contact Surface Core Core Contact Surface Core SS-CNPs film Stearoyl group Crystalline regions formed by stearoyl groups Cellulose chain Tetrahydrofuran (THF) 20

21 ph responsive NPs Thiol-ene reaction O RO O 8 O OR RO O R=COCH 2 (CH 2 ) 7 CH=CH 2 OR OR O O n Thiol-ene reaction O 8 O O R 3 O R O 3 O OR 3 CH 3 N CH 3 S HCl OR 3 O n O OR 3 R 3 =COCH 2 (CH 2 ) 8 CH 2 SCH 2 CH 2 N(CH 2 CH 3 ) 2 Cellulose 10-undecenoyl ester R'' ph=7 R'' N R' NH R''' ph=4 R' R''' 500 nm 500 nm R 4 O O 8 O O R 4 O O OR 4 H 3 C N CH 3 S HCl OR 4 O n O OR 4 R 4 =COCH 2 (CH 2 ) 8 CH 2 SCH 2 CH 2 N(CH3) 2 HCl Nanoscale, 2016, 8, 648

22 Nanoprecipitation

23 Flower-like Particles via crystallization of cellulose stearoyl esters 55 C RT 23

24 Non-wetting surfaces Excellent superhydrophobicity against diverse liquids Aqueous solutions of salts & different ph values Protein solutions, BSA: aqueous bovine serum albumin Different viscosities (water: ~0.01 Pa s, Glycerol: Pa s, 25 C)

25 Thank you for your attention! 25