Inorganic-Organic Hybrid Materials

Transcript

Inorganic-Organic
Hybrid Materials
Bressanone Sept. 2006
Hybrid Materials
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Hybrid Materials
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1
Composites – Hybrid Materials
cm
µm
nm
CLASSICAL COMPOSITES
Property Improvement:
• mechanical stability
• thermal stability
• photochemical stability
Hybrid Materials
From Molecules to Nanobuilding Blocks
Various properties possible depending on precursors and processing
Hybrid Materials
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Hybrid Materials
Composite Material
Compound 1
Macroscopic
phases
Compound 2
Hybrid Material
Molecular or
nanoscale
building blocks
The goal is to create materials with specific combinations of properties by
combining different molecular building blocks in various ratios and by controlling
their mutual arrangement
Control at the nanolevel
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2
Homogeneity
vs.
Problems: scatters light,
mechanical properties, etc…
Control over homogeneity:
• precursor selection (functional group)
• reaction conditions: kinetics, solvent, etc.
• interactions between the components
Hybrid Materials
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Typical Properties of Organic and Inorganic Materials
Properties
Organic materials
(polymers)
Inorganic materials
(glass, ceramics)
Nature of bonds
covalent [C–C], van der
Waals, H-bonding
low
low (except polyimides)
low
low
elastic
flexible
rubbery (depending on Tg)
hydrophilic or hydrophobic
ionic or covalent
high
high
high
high
hard
strong
brittle
hydrophilic
insulating to conductive
non-magnetic
at low temperatures and
pressures (molding, casting,
etc.)
insulating to semiconductors
magnetic
at high temperatures and/or
pressures (sintering, glass
forming)
Tg
Thermal stability
Density
Refractive index
Mechanical properties
Hydrophobicity
Electronic and
magnetic properties
Processability
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3
Nanolego
Form
Function
Geometry of the linkage
Connectivity
Kind of linkage
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Nanolego: Building Blocks
Inorganic Building Blocks
O
O
O
O
Si
O
O
Ti
O
Mechanical, optical, electrical,
magnetical properties
O
O
O
Connecting Blocks
O
H2C
O
Si
O
O
O
X
Ti
O
Y
O
Reduction of the crosslinking density,
coupling sites between inorganic /
organic components
Organic Building Blocks
Functional groups, crosslinking,
polymerizability
A
Flexibility, elasticity, processability
H2
C
H2
C
C
H2
C
H2
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4
Nanolego: Linking the Building Blocks
Polymerization / Polycondensation
CH3
COOR
CH3
COOR
CH3
COOR
O
HO
OR
O
+
O
H2N
HN
O
O
HN
O
NH2
OH
NH
Sol-Gel-Process
RO
Si
OR
OR
HO
+ H2O
Si
OH
OH
OH
OR
HO
- H2O
+ H+
HO
Si
OH
OH
O
OH
Na4SiO4
Si
HO
Si
OH
OH
OH
OH
Self-Organization
Zn(NO3)2 +
HO
O
Zn4O(terephthalate)6
O
OH
Hybrid Materials
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Nanolego: Critical Issues
¾ Homogeneous distribution of the building blocks in the material
¾ Stable distribution: no microphase separation
¾ Interaction between the two components
¾ Structure-property relationships
¾ Inclusion of functionalities
¾ Tailoring of
molecular structure ↔ nanostructure ↔ microstructure
(= hierarchical structure design)
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5
Precursors
Molecular precursors
Clusters (nano-building blocks, NBB)
Alkoxysilyl-substituted organic polymers
Pre-formed nanostructures
Classes of sol-gel hybrid materials
Physically entrapped components
Functionalized inorganic networks
Interpenetrating networks
Dual networks
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Molecular Precursors
Network Modifiers (non-reactive organic groups)
(RO)3Si CH3
(RO)3Si
(RO)3Si
Precursors with Functional Organic Groups
(RO)3Si
(RO)3Si
O
O
+ HS-Si(OR)3
(RO)3Si
(RO)3Si
O
O
RO
(EtO)3Si
O
Ti
N
H
N
O
O
N
N
R
OR
OR
(RO)3TiSO3(Co-phthalocyanine)
polymerizable organic groups
⇒ inorganic-organic hybrid polymers
NO2
O
O
NH2
N
H
groups with other organic functions
Hybrid Materials
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6
Nano Building Blocks: Polyhedral Oligomeric Silsesquioxanes (POSS)
Hybrid Materials
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Nano Building Blocks: Functionalized Metal Oxide Clusters
Ti16O16(OEt)24(OPr)8
(same with
OCH2CH2OC(O)C(Me)=CH2)
Zr6O4(OH)4(methacrylate)12
covalent interaction
[(BuSn)12O14(OH)6]2+·2 methacrylate[SiW11O39(OSi2(C6H4CH=CH2)2)]4-
Hybrid Materials
electrostatic interaction
14
7
Bridged Alkoxysilanes
(RO)3Si
(RO)3Si-(CH2)n-Si(OR)3
Si(OR)3
H
N
(RO)3Si-(CH2)m
H
(CH2)n N
H
N (CH2)n
C
H
N
H
N (CH2)m-Si(OR)3
O
O
(EtO)3Si
C
O
O
N
N
N
H
(EtO)3Si
H
N
SO2(CH2)2O
N
O
O
Si(OEt)3
O
2+
NH
(RO)3Si
H2N
NH2
Ni
NH
Si(OR)3
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Alkoxysilyl-Substituted Organic Polymers
CH3
(EtO)3SiO
Si
O
Si(OEt)3
n
CH3
(EtO)3Si-(CH2)3 O
CH3
H2
C
n
C
O
(CH2)4-O
n
O
Si(OMe)3
(CH2)3-Si(OEt)3
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8
Pre-formed Nanostructures
(Nano)Particles
Preformed Oligomers
and Polymers
Clays / Layered Materials
Porous Materials
(Nano)Fibres, Nanotubes
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Consequences of Introducing Organic Substituents
¾ Reduced degree of crosslinking of the inorganic network
¾ Polarity changes (changes in hydrogen bonding)
¾ Reactivity change of the remaining alkoxide groups
(electronic and steric effect of the organic substituents)
These effects are an inevitable consequence
of the organic modification
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9
Degree of Crosslinking
Si(OR)4-nRn
n = 1-3
Si(OR)2R2
Si(OR)3R
R
R
R
Si
Si
Si
O
O
O
R
R
Si
Si
O
O
O
O
O
O
O
O
Si
Si
Si
Si
R
R
R
Silsesquioxanes
R
R
O Si O
Si
O
O
R
R
O
n
O
R
Si(OR)R3
R
Si O
Si R
R
R
R'
Oligo- and Polysiloxanes
Dimers
R
Si
O
O
R
O
Si
Si
OR
Si
O
O
Si
Si O
O
R
R
R
Polyhedral Oligomeric
Silsesquioxanes
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Influence on Reaction Rates
Example:
(RO)3Si
Si(OR)3
0.6 M in methanol, 25°C
The dashed line is pH vs. gel time for
Si(OMe)4 (2.0 M in methanol, 60°C).
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10
Influence on Reaction Rates
(acac = acetylacetonate, ftac =trifluoroacetylacetonate, dbzm = dibenzoylmethanide)
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Precursors
Interpenetrating structures
Dual networks
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11
Types of Inorganic-Organic Hybrid Materials by Sol-Gel Processing
Physically entrapped
molecules, particles, etc.
Interpenetrating inorganic
and organic networks
Class I materials:
weak interactions
R R
RR
R
Class II materials:
strong interactions
RR
R R
R R
RR
RR
R R
RR
R
R
R R
R
R RR
RR
R
R
R
R
RRR
R
R
Modification of the gel
network by organic groups
Dual inorganic and organic networks
connected by covalent bonds
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Entrapped Biomolecules
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Entrapped Biomolecules: Glucose Sensor
NO-releasing glucose biosensor
(cleaved NO suppresses degradation by bacteria)
O
Glucose oxidase in MeSi(OEt)3 Gel
SiO2
Si
CH3
OH
N NO
H
O Si (CH2)3 N (CH2)6 N
H
in polyurethan
M.H.Schoenfisch et al., 2004
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Entrapped Inorganic Particles: Dental Filling
abrasion 9 µm
shrinkage 1,97 vol%
adhesion 25,8 / 27,6 MPa
pyrogenic
silica
(≈ 40 nm)
+
standard
dental glass
particles
(≈ 0,7 µm)
Hybrid Materials
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13
Entrapped Inorganic Particles: Controlled Release
in SiO2
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Precursors
Dual networks
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14
Heterogenization of Homogeneous Catalysts
Classical approach
RO
RO
RO
Si
RO
Sol-gel approach
+ MLn
A
RO
Si
A
RO
MLn
+ MLn
A
O
Si
A
Si
O
MLn
A
MLn
O
O
+ MLn
+ MLn
Si
O
+
A
RO
A
Si
Si
O
E(OR) n
A
RO
O
RO
O
RO
O
RO
Si
MLn
+ E(OR) n
O
RO
A
RO
+
O
Si
RO
RO
RO
RO
RO
Si
A
O
+
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Heterogenization of Catalysts by Sol-Gel Processing
RO
Si
RO
A
MLn
Examples:
+ Si(OR)4
RO
Si
O
A
Ph
C
O
Ph
P
Si(OR)3
Ph
MLn
O
(EtO)3Si
Poren
pores
(EtO)3Si
sol-gel
Sol-GelProzeß
processing
Ph Cl
P
Ru
P
Ph Cl
Ph
P
P
Ph
Si(OEt)3
Si(OEt)3
Synthesis of N,N-diethylformamide from CO2, H2
and diethylamine
A. Baiker et al., 1999
K
K
Cl
Rh
P
More active in the hydrosilation of 1-hexene than
Rh(CO)Cl(PR3)2
U. Schubert et al., 1989
O
SiO2 /
Ph
(RO)3Si
K
K
K
O
K
K
(RO)3Si
K
K
aktive
Spezies
= katalytisch
catalytically
active
species
N
H
NH2 N
Cu2+
NH
2
Catalyst for the oxidation of 3,5-di-tert.butylcatechol
to the quinone
M. Louloudi et al., 1998
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15
Coatings with Optical Properties
Photochromism: fast for optical switches, for eye protection, privacy shields
slow for optical data storage, energy conserving coatings, etc...
Example: Spirooxazine derivative
hν1
N
N
O
Δ or hν2
N
N
O
Embedding in sol-gel coatings:
For sufficient photochromism: dye concentration > 25 wt% → mechanical stability of
sol-gel film is deteriorated.
Grafting of the dye to the
sol-gel matrix → higher chromophore
concentrations can be achieved
without affecting the mechanical integrity
of the sol-gel matrix
Si(OEt)3
HN
O
N
N
O
O
Photochromic coating on paper
Hybrid Materials
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Precursors
Dual networks
Hybrid Materials
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16
Interpenetrating Networks
Sequential
Sequentialtwo-step
two-stepprocess:
process:
Second
Secondnetwork
networkis
is
formed
formedin
inthe
thefirst
first
IPN
Examples:
¾ Generation of the organic polymer in the pores of an inorganic porous material
(in channels of zeolites or mesoporous materials, between sheets of a layered
lattice, such as a clay mineral) ⇒ rigid inorganic moiety with a regular pore or
channel structure in the nanoscale
¾ Inorganic structures form and interpenetrate an organic polymer (difficulties:
incompatibility between the moieties ⇒ phase separation)
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Interaction via hydrogen bonds to silanol groups of the forming silica
Organic polymers with hydrogen bonding ability:
n
n
NMe2
O
OH
n
n
n
O
O
OMe
n
O
O
O
N
OH
poly(VP)
poly(DMAA)
poly(VA)
poly(VAc)
poly(MMA)
poly(HEMA)
Si(OR)4 and/or RSi(OR)3
H2O, [Kat]
No macro phase separation
Resulting materials: high degree of homogeneity
and optical transparency
Important reaction parameter: pH
Change of crosslinking density and interaction with polymer using RSi(OR)3/Si(OR)4 mixtures
Hybrid Materials
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17
+
Sol from GLYMO and Al(OsBu)3 (H2O/HCl)
Poly(isopren-block-ethylenoxide)
swollen in THF/CH3Cl
(RO)3Si
O
O
Nanostructured hybrid polymer
U.Wiesner et al., 2004
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Organic
Monomer
Inorganic Monomer
Catalyst
Solvent
AIBN
TEOS
HF
Water
O
OH
C. L. Jackson et al. Chem. Mater. 1996, 8, 727
O
Initiator
Addition of tetrakis(2-(acryloxy)ethoxy)silane
improves homogenity
TEM images of the nanocomposites:
Increasing Sol-Gel Catalyst Concentration => Faster Reaction
Hybrid Materials
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18
Nanocomposites: Polymer-Clay
Layered solid
Layered solid
+ Monomer
(Polymerization)
Exfoliated layers
+ Polymer
+ Monomer
(Polymerization)
or
+ Polymer
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Hybrid Materials
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19
15 μm glass fibre in polyolefin
1 nm thick montmorillonite
sheet in epoxy resin
Hybrid Materials
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Nanocomposites: Intercalation of Polymers in Pores
Direct Intercalation
+
Polymer
Porous Host
Problems:
¾ Pore diameter ↔ size of Polymer
¾ Diffusion of polymer
⇒ Usually only end of polymer sits in pore but not the whole chain
Hybrid Materials
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20
Nanocomposites: Polymerization in Pores
Monomer
Intercalation
+
Monomer
Polymerization
Porous Host
Monomer is interacalated into the pores
(vapor, liquid), then polymerization
T. Aida et al. 2000
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Nanocomposites: Polymerization in Pores
T. Aida et al. 2000
T. Bein et al. 1992
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21
Precursors
Dual networks
Hybrid Materials
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Dual Network Structures
Preparation strategies
Concomitant formation of the inorganic and organic structures
Stepwise formation of the organic and inorganic networks
¾ from pre-formed organic structures
¾ from pre-formed inorganic structures
Options

Chemical composition of the inorganic component(s)
Chemical composition of the organic component(s)
Proportion of the inorganic/organic components
Curing method (thermal / photochemical)
Dimension of the inorganic / organic components (molecular, nanometer,
extended)
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22
Concomitant Formation of Inorganic and Organic Network
Typical procedure
Metal Alkoxides
Metal Salts
+ water (ev. catalyst or additives)
- alcohol
Precursors
Hydrolysis
Condensation
Sol
Gelation
formation of inorganic network
Gel
formation of organic network
Hardening
(thermal or uv)
Many Examples:
Coatings Section
Hybrid Polymer
Hybrid Materials
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Often used precursors
O
(RO)3Si
(RO)3Si
O
(RO)3Si
O
O
O
O
or
O
OH
O
O
+ Zr(OR)4
O
+ Si(OR)4, Zr(OR)4, Al(OR)3,
etc.
+ acrylate, epoxide
monomers, etc.
increase of “inorganic /
organic ratio”
decrease of “inorganic /
organic ratio”
Hybrid Materials
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23
O
O
O
O
O
O
O
O
O
O
O
O
O
Sequential
formation of
the organic
network
UV-polymerization
of methacryl groups
photo-initiator, hν
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
thermal polymerization
of epoxy groups
ΔT
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
Hybrid Materials
O
47
*) SBU: Sequentially Built-up
O
H2O / NaF
Si
CH2O
SiO2
4
O
CH2OH n
H2O / NaF
O(CH2)2O Si
4
aq. ROMP
O
+
Free Radical
Polymerization
SiO2 +
Hybrid Materials
O
O(CH2)2OH 4
48
24
Photochemical Crosslinking (3D Laser Lithography)
Coating or forming of
ORMOCER®
(with chromophor as UV initiator)
Direct 3D-laser writing
(2-photon polymerisation with
femtosecond laser pulses)
Requirements for hardening:
Development of the structure
(removal of uncured
ORMOCER®)
•
precise focussing
•
2-photon process
•
polymerisation in Ormocer® layer
(O2 protection)
•
chromophor as initiator
Ormocer® = Organically modified Ceramics
Hybrid Materials
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CAD File
Layer model
‚Venus of Milo‘ in
ORMOCER® (REM)
I am made
from
ORMOCER®!
Hybrid Materials
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25
Hybrid Materials
51
Hybrid Polymers from Pre-Formed Organic Polymers
CH3
Low shrinkage by the use of
prepolymerized materials
CH3
x
acrylic component
silane component
(MeO)3Si(H2C)3O
O
y
MeO
O
1. inorganic condensation
2. organic polymerization
acrylic monomer + polymer
(incomplete polymerization)
inorganic condensation
between fully
polymerized polyacrylate
Hybrid Materials
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26
Hybrid Polymers from Pre-Formed Organic Polymers
A.-M. Caminade, J.-P. Majoral, J. Mater. Chem., 2005, 15, 3643-3649
Hybrid Materials applying Dendrimers
Porous Materials using Dendrimers as Templates
Hybrid Materials
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Hybrid Polymers from Pre-Formed Inorganic Structures
Hybrid Materials
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27
Improved Properties through Controlled
Reinforcement of Polymer Chains at the Molecular Level
R
O
Si
R
Si
R
Si
O
Si
O
O R
Si
O
Si
R'
O
O
O
O
RO
O
Si
R
Si O
R
www.hybridplastics.com
Property enhancements via POSS
observed in POSS-copolymers and blends
• Increased Tdec
• Increased Tg
• Reduced Flammability
• Reduced Heat Evolution
• Lower Density
• Disposal as Silica
• Extended Temperature Range
• Increased Oxygen Permeability
• Lower Thermal Conductivity
• Thermoplastic or Curable
• Enhanced Blend Miscibility
• Oxidation Resistance
• Altered Mechanicals
• Reduced Viscosity
Hybrid Materials
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POSS for fire retardant materials
Hybrid Materials
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28
Polymerizable Metal Oxo Clusters
X
X
X
X
X
X
X
X
X
Polymerizable groups X
Zr6O4(OH)4(methacrylate)12
for free radical polymerization
Zr6O4(OH)4(5-norbornene-2-carboxylate)12 for ROMP
Hybrid Materials
57
Metal Oxo Clusters as Initiators for ATRP
multifunctional initiator + monomer
X
X
+
catalyst
X
X
X
X
X
X
+ solvent
= PMMA, PS, PtBuA
X
catalyst = pmdeta / CuBr or CuCl
e.g. Ti6O4(OOCCBrMe2)(OiPr)8
0.9
100
0.7
ln (M0/M)
G.Kickelbick et al.
80
Y=0,0058*X
R=0,997
70
60
0.5
50
0.4
40
0.3
Polydispersities <1.5. 0.2
90% of the chain ends 0.1
still active after isolation 0.0 0
Hybrid Materials
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Conversion [%]
0.6
90
ln (M 0/M)
linear Fit for ln (M 0/M)
0.8
20
10
0
20
40
60
80
100 120 140 160
Time [min]
58
29
Combination of polyoxometallates (electrochromism, photochromism,
conductivity, redox activitities) + conjugated molecules and polymers
⇒ electrically active organic materials (light emitting diodes, field-effect
transistors, solid-state lasers)
Monofunctionalization of Mo6O192-
Examples:
Z. Peng et al. 2004
Hybrid Materials
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Z. Peng et al. 2004
Hybrid Materials
60
30
Magnetic Polymers
Mn12O12(OOC-CH=CH2)16
Radical polymerization
+ CH2=CMe-COOMe
PMMA crosslinked by Mn12
„Mn12“
total cluster spin S = 10
(4 MnIV, S = 3/2 + 8 MnIII, S = 2)
Superparamagnetic
Hybrid Materials
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Preparation of nanoparticles
„Stöber-Process“
Si(OEt)4 + NH4OH
FG
Surface modification
O
N
NC
CH3
N
CH3
CH3
CN
SiO
FG
Si
Si
FG
O O O OO O
O
Si
O
O
O
O
O
O
Si O
2
O
O
O Si
O
O
FG
O
O O OO
Si
FG
FG
Si
Initiators at the surface, e.g.
(EtO)3Si(H2C)3O
HO HO OH OH
HO
OH
HO
HO
OH
HO
OH
2
HO
OH
HO
OH
HO
OH
HO
HO HO OHOH
FG
O
CH3
(EtO)3Si(H2C)3O
Br
CH3
SiO
(RO) 3 Si
FG
FG
Polymerization from the functionalised surface
AFM
G.Kickelbick et al.
Hybrid Materials
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Inorganic-Organic Hybrid Materials

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