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Im Kleinen liegt Großes
Nanostrukturierte funktionelle Materialien aus
Holzkomponenten
Jr.-Prof. Dr.
Kai Zhang
JP Holztechnologie & Holzchemie
Georg-August-Universität Göttingen
NHN Tagung, Jun. 2017
1
Kai Zhang, Uni Göttingen

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http://www.nature.com/news/the-wooden-skyscrapers-that-could-help-to-cool-the-planet-1.21992
53-metre dormitory at the University of British
Columbia in Vancouver
Kai Zhang, Uni Göttingen

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3
paper
textile
Construction
materials
Many others
energy
Wood
Kai Zhang, Uni Göttingen

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

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Nanocellulose
5
Kai Zhang, Uni Göttingen

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Holzchemie und
Cellulosechemie
6
Kai Zhang, Uni Göttingen

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Surface coating (e.g. super/hydrophobization)
nanoparticles / microparticles
Responsive, self-standing films
(1)
The Journal of Physical Chemistry C
2014,
118
, 2408-2417. (2) Angewandte Chemie Int Edition, 2014, 12618-12623. (3) Chemistry
– A European Journal 2015, 21,
1-8 (4)
Physical Chemistry Chemical Physics,
2014, 26322-26329. (5) Advanced Functional Materials,
2015,
, 25, 1434-1441. (6) Nanoscale, 2016,
7
8, 648.
gels
Funktionelle Materialien
Kai Zhang, Uni Göttingen

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

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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
Kai Zhang, Uni Göttingen

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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
, 12618-12623.
Cellulose nanocrystals (CNC) as substrate for biomacromolecules, e.g enzymes.
Kai Zhang, Uni Göttingen

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Example:
CNC with immobilized galactose oxidase with maintained activity
Kai Zhang, Uni Göttingen

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Responsive CNC via surface-immobilization of stimuli-responsive groups
e.g. with stimuli-responsive
rhodamine spiroamide
Potentially for biomedical imaging and detection
L. Zhao, W. Li, A. Plog, Y. Xu, G. Buntkowsky, T. Gutmann,*
K. Zhang
*
Physical Chemistry Chemical Physics,
2014, 26322-26329.
Low amount of RhB spiroamide: 0.2±0.01 mmol/g
Functional materials based on crystalline nanocellulose
Kai Zhang, Uni Göttingen

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Pre-organized
cellulose nanocrystal crosslinker for robust hydrogel
Huang, Wang, Rehfeldt,
Zhang. Macromolecular Rapid
Communication, 2017, 38,
1600810
Kai Zhang, Uni Göttingen

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1% CNC as prepared, tensile trial
Kai Zhang, Uni Göttingen

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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, 1434-1441.
Spheric crystalline cellulose nanoparticles
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Kai Zhang, Uni Göttingen

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

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Gelation behaviour of suspensions
Elastic G ad viscous G odulus as a fuctio of
oscillatory shear frequency
Changing concentration: gelation at RT
5 mg/ml in THF
Changing temperature: thermo-reversible gelation
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Kai Zhang, Uni Göttingen

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

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Solvent-responsive shape memory
Good shape fixation by heating or solvent treatment;
One-way solvent responsive shape-memory behavior;
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Kai Zhang, Uni Göttingen

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Proposed mechanism
SS-CNPs film
Core
Contact Surface
Core
Core
Contact Surface
Core
Core
Contact Surface
Core
Stearoyl
Crystalline
group
regions formed by stearoyl groups
Cellulose chain
Tetrahydrofuran (THF)
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Kai Zhang, Uni Göttingen

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Nanoscale, 2016, 8, 648
R=COCH
2
(CH
2
)
7
CH=CH
2
500 nm
pH=7
500 nm
pH=4
N
S
O
O
O
R
3
O
O
R
3
O
O
R
3
O
R
3
R
3
O
On
O
8
HCl
CH
3
CH
3
N
S
O
O
O
R
4
O
O
R
4
O
O
R
4
O
R
4
R
4
O
On
O
8
CH
3
H
3
C
HCl
Thiol-ene reaction
Thiol-ene reaction
R
3
=COCH
2
(CH
2
)
8
CH
2
SCH
2
CH
2
N(CH
2
CH
3
)
2
R
4
=COCH
2
(CH
2
)
8
CH
2
SCH
2
CH
2
N(CH3)
2
·HCl
N
R'
R'''
R''
H
N
R'
R'''
R''
O
O
O
R
O
O
R
O
O
R
O
R
R
O
O
n
8
O
Cellulose 10-undecenoyl ester
pH responsive NPs
Kai Zhang, Uni Göttingen

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Nanoprecipitation
Kai Zhang, Uni Göttingen

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Flower-like Particles via crystallization of cellulose stearoyl esters
23
55
°
C
RT
Kai Zhang, Uni Göttingen

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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: 0.934 Pa.s, 25°C)
Kai Zhang, Uni Göttingen

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Thank you for your attention!
25
Kai Zhang, Uni Göttingen