Hi Greg,
What I find worthwhile mentioning for sure that the FTIR technique still seems to be used in Pratsinis’ group for determining flame temperatures. This technique was developed and established by Phil.
Hope this helps, Best regards Hendrik
Dr. Hendrik Kammler
TRD Head of Operations and Global TRD CI Network Lead Novartis Pharma AG
Postfach CH-4002 Basel Switzerland
Phone +41 61 324 0591 Mobile +41 79 592 9157
hendrik.kammler@novartis.com www.novartis.com
January 15, 2016 Fort Washington Chili
Cincinnati
Nanoparticle Formation
Solution Route
-Separation
-Surface Tension
(Pore/Particle Collapse) -Solvent Disposal
-Reaction Rate is Slow -Transport is Slow -Batch Process
Aerosol Route
-Particles are Pre-Separated -No Surface Tension Issues -No Solvent Disposal
-Reaction Rate is Fast -Continuous Process
-Rapid Supersaturation & Dilution
Kelvin Laplace
Nano-particles form far from equilibrium.
T ~ 2500°K
Time ~ 100 ms
φ
~ 1 x 10
-6d
p~ 5 to 50 nm
Kammler HK, Beaucage G, Kohls DJ, Agashe N. Ilavsky J J Appl. Phys. 97(2005) (Article 054309).
What is SAXS?
X-ray, λ θ
d = λ/(2 sin θ) = 2π/q
Branched Aggregates
What is SAXS?
Guinier’s Law
X-ray, λ θ
d = λ/(2 sin θ) = 2π/q
What is SAXS?
Guinier and
Porod Scattering
X-ray, λ θ
d = λ/(2 sin θ) = 2π/q
What is SAXS?
Polydispersity
Particle size distributions from small-angle scattering using global scattering functions, Beaucage, Kammler, Pratsinis J. Appl.
Cryst. 37 523-535 (2004).
X-ray, λ θ
d = λ/(2 sin θ) = 2π/q
What is SAXS?
Linear Aggregates
Beaucage G, Small-angle Scattering from Polymeric Mass Fractals of Arbitrary Mass- Fractal Dimension, J. Appl. Cryst. 29 134-146 (1996).
X-ray, λ θ
d = λ/(2 sin θ) = 2π/q
What is SAXS?
Branched Aggregates
Beaucage G, Determination of branch fraction and minimum dimension of fractal aggregates Phys. Rev. E 70 031401 (2004).
X-ray, λ θ
d = λ/(2 sin θ) = 2π/q
5mm LAT 16mm HAB Typical Branched Aggregate
dp = 5.7 nm z = 350
c = 1.5, dmin = 1.4, df = 2.1
br = 0.8
Branched Aggregates
Beaucage G, Determination of branch fraction and minimum dimension of fractal aggregates Phys. Rev. E 70 031401 (2004).
APS UNICAT
Silica Premixed Flames J. Appl. Phys 97 054309 Feb 2005
* same for all flames!
TiCl
4Diffusion Flame Nucleation and Growth
( )
kT E
d d R
z
p f
D -
÷÷ ø ö çç
è æ
~
ln 2
~ ln
Activated growth for z
Titania Diffusion Flame from TiCl4
Beaucage G, Agashe N, Kohls D, Londono D, Diemer B
Silica Diffusion Flame
Axial Particle Growth follows
Classic Diffusion Limited
Surface Growth, d ~ t
1/2Kammler HK, Beaucage G, Kohls DJ, Agashe N. Ilavsky J J Appl. Phys. 97(2005) (Article 054309).
Summary:
1) SAXS as a tool for in situ observation of structure 2) Homogeneous nucleation
appears to be a common feature of flame growth.
3) A wide range of particle growth mechanisms can be involved
4) Branching can be monitored in terms of the mass fractal dimension but
5) A much richer description of
aggregate growth is give by
inclusion of new model for
branched structure.
Number Density and Primary Particle Size versus Height Above the Burner
Silica Premixed Flame
(Data agree with Choi Cho Lee and Kim 1999 Fig. 9.)
. . Nucleation, Issues:
“Chemical” Nucleation Homogeneous Nucleation Gibbs-Thompson (Kelvin)
r = 2gv RTln p pæ s
è ö
ø
r is the critical size for stability. For high-T & low ps (solid) in a typical flame r < 0.1 nm
Chemical reaction leads directly to solid particles of molecular scale that grow by coalescence continuously from about
r ~ 0.5 nm No Spontaneous Nucleation Event
. .
. . . .
Silica Volume Fraction (Conversion)
Height Above Burner Homogeneous
Nucleation
Surface Nucleation
Higher = Smaller
Narrower = Lower Polydispersity
c
(c )surface
Girshick/Giesen Model May Explain This Behavior
In Flames and Other Aerosols
Growth
r ~ t
12
r ~ t
Axial Particle Size
and Growth for Titania Diffusion Flame
r = 2gv RTln p pæ s
è ö
ø
Gibbs- Thompson
(Kelvin)
dp ~ t Reaction limited growth.
Aggregation
Mass Fractal dimension,
d
f, and degree of aggregation, z.
Nano-titania from Spray Flame df
d
pz R ÷ ÷ ø ö ç ç
è
= a æ 2
Problem: Disk d
f= 2; Gaussian Walk d
f=2;
Random aggregation (right) d
f~ 1.8;
Randomly Branched Gaussian d
f~ 2.5;
Self-Avoiding Walk d
f= 5/3
2R/dp = 10, a ~ 1, z ~ 220 df = ln(220)/ln(10) = 2.3Tc
1.8 ms 1.25 ms
0.55 ms Zirconia Spray Flame
Fractal dimensions: d
f, d
min, c, the degree of
aggregation (z), and the molar branch fraction,
Br-F F
-F F
R d
pdf
d
pz R ÷ ÷ ø ö ç ç
è
~ æ
min
min
~
d
d
pz R
p ÷ ÷
ø ö ç ç
è
= æ
~ p
cp
df dminz =
d
minshould effect perturbations & dynamics.
Beaucage G, Determination of branch fraction and minimum dimension of fractal aggregates Phys. Rev. E 70 031401 (2004).
Six Arm Polyurethane Star Polymers
Kulkarni A, Beaucage G using Data of Jeng, Lin et al App. Phys. A (2002)
5mm LAT 16mm HAB Typical Branched Aggregate
dp = 5.7 nm z = 350
c = 1.5, dmin = 1.4, df = 2.1
br = 0.8
Branched Aggregates
Beaucage G, Determination of branch fraction and minimum dimension of fractal aggregates Phys. Rev. E 70 031401 (2004).
APS UNICAT
Silica Premixed Flames J. Appl. Phys 97 054309 Feb 2005
Signatures of Possible Mechanisms for Structural Change
Premixed Silica Flame,
Hexamethyldisiloxane precursor
5mm LAT 16mm HAB
Typical Branched Aggregate dv/s = 9.5 nm, z = 223, c = 1.10, dmin = 2.07, df = 2.28 br = 0.38
Premixed Silica Flame
5 mm lateral 16 mm lateral
Silica Premixed Flame
Primary Particle Growth and Entrainment
Complicate the Situation
Surface Nucleation Homogeneous Nucleation
G = DHr3 + 6
g
r2
G = DHr3 + 4
g
r2 Lower Energy Barrier for Surface Nucleation (Lower Supersaturation is Needed)High particle density can be accommodated
by:
Structure Depends on Temperature & Concentration
T em pe ra tu re , C on ce nt ra ti on , N um be r
Height Above Burner Nucleation
Coalescence
Surface Nucleation
Aggregation Agglomeration (Hard)
(Soft)
1) coalescence and sintering 2) aggregation hard agglom.
3) agglomeration
soft agglom.
Particle Size Distribution Curves From SAXS:
(Persistence effects not observed) Unified Method
i) Global fit for B
Pand G.
ii) Calculate PDI (no assumptions &
unique “solution”)
iii) Assume log-normal distribution for
gand distribution curve (or other models)
iv) Data to unique solution Solution to distribution
Advantages
Generic PDI (asymmetry also) Global fit (mass fractal etc.) Direct link (data => dispersion) Use only available terms
Simple to implement
G R PDI B
P g62 . 1
4
=
( ) ( )
1212
ln ln úûù
êëé
=
= PDI
g
2 1 14
2
3
25
ú ú û ù ê ê
ë
= é
e
m R
gParticle size distributions from small-angle scattering using global scattering functions, Beaucage, Kammler, Pratsinis J. Appl. Cryst.
37 523-535 (2004).
Particle Size Distribution Curves from SAXS
PDI/Maximum Entropy/TEM Counting
Outline:
1) Fractal dimensions and degree of aggregation 2) Persistence length and substructural scaling
3) Minimum number of features 4) Small-angle scattering for branched structures
5) Ceramic aggregates
6) Polymer chains in dilute conditions 7) Networks
8) Unfolded proteins 9) Summary
http://www.eng.uc.edu/~gbeaucag/Classes/IntrotoPolySci/PicturesDNA.html
Chain persistence
PHB = polyhydroxybutyrate (side chain = -CH3) PHV = polyhydroxyvalerate (side chain = -CH2CH3) These are short chain branching similar to branching in polyolefins
Persistence length of isotactic poly(hydroxyl butyrate) Beaucage G, Rane S, Sukumaran S, Satkowski MM, Schechtman LA, Doi Y Macromolecules 30 4158-4162 (1997).
Rheology and persistenc in polyhydroxy alkonates. Ramachrichnan R, Beaucage G, Satkowski M, Melik D in preparation J. Rheology.
Persistence length of isotactic poly(hydroxyl butyrate) Beaucage G, Rane S, Sukumaran S, Satkowski MM, Schechtman LA, Doi Y Macromolecules 30 4158-4162 (1997).
Rheology and persistenc in polyhydroxy alkonates. Ramachrichnan R, Beaucage G, Satkowski M, Melik D in preparation J. Rheology.
Chain persistence
Intrinsic and Topological Stiffness in branched polymers. Connolly R, Bellesia G, Timoshenko EG, Kuznetsov YA, Elli S, Ganazzoli G Macromolecules 38 5288-5299 (2005).
N = Length of Side Chain
S = Number of Flexible Spacers Longer Side Chain Causes
Stiffer Chain
(no helical structure)
Chain persistence
Determination of d
min, c and d
f.
Beaucage G, Determination of branch fraction and minimum dimension of fractal aggregates Phys. Rev. E 70 031401 (2004).
( )q Bfqdf
I = -
( ) ÷÷
ø ö çç
è
= æ - exp 3
2 2
Rg
G q q I
There appears to be a quantifiable difference in scattering for different dmin and
the same df.
Determination of d
min, c and d
f.
Beaucage G, Determination of branch fraction and minimum dimension of fractal aggregates Phys. Rev. E 70 031401 (2004).
( )q Bfqdf
I = -
( ) ÷÷
ø ö çç
è
= æ - exp 3
2 2
Rg
G q q
I
df c dmin
Gaussian
Chain 2 1 2 Disk 2 2 1
Static scattering can be used to obtain dmin.
Branched polystyrene in a good solvent
d
minshould be 5/3 (1.67) for self-avoiding walk
Mw/Mn ~ 2 Good Solvent Scaling for c = 1 and c > 1
Hyperbranched polyesteramides
Sample Rg,2 df dmin c Description Mn* Mw*
1 17.2 (15.5) 1.3 1 1.3 Regular 1.5 3.6
2 22.2 (21.6) 1.64 1.67 1 Linear 1.8 5.9 3 26.8 (30.5) 1.60 (1.63) 1.09 1.47 Close to Regular 2.4 11.0 4 57.5 1.74 (1.68) 1.59 1.09 Close to Linear 2.4 59.0 5 288.3 1.63 (1.63) 1.34 1.21 Branched 2.8 248
One pot synthesis semi-random Dendrimers
For samples 3 & 4 polydispersity is apparent due to linear
vs branched chains.
Linear is local persistent branching Regular is global structural branching
*Mn & Mw in kg/mole
Molecular Structure Characterization of Hyperbranched Polyesteramides ETF Gelade, B Goderis, K. Mortensen et al. Macromolecules 34 3552-58 (2001)
Outline:
1) Fractal dimensions and degree of aggregation 2) Persistence length and substructural scaling
3) Minimum number of features 4) Small-angle scattering for branched structures
5) Ceramic aggregates
6) Polymer chains in dilute conditions 7) Networks
8) Unfolded proteins 9) Summary
http://www.eng.uc.edu/~gbeaucag/Classes/IntrotoPolySci/PicturesDNA.html
8) Unfolded proteins
Is the molten golbule a third phase of proteins? VS Pande & DS Rohksar, PNAS 95 1490-94 (1998)
Simulation Results, g is denaturant
-Unfolded state is analogous to gas state (following Flory random walk model as applied by Pande) -Dense states not associated with biological activity could be analogous to glassy state (molten globule) -0 conformational entropy native state is analogous to crystalline state
-Unfolded state contains some:
Chain persistence associated with fluctuating helicies and -sheets
Crosslink/disulfide/cystine-cystine bonds that act as branching sites
hydrophobic interactins that may appear to be branching sites
-Conformational transitions should show increase in df and c towards a regular 3d structure
8) Unfolded proteins
“a Gaussian-like conformation”
Mapping the cytochrome C folding landscape
Julia G. Lyubovitsky
Caltech 2003 Biochemistry
Rg df dmin c
125Å 2.05 1.07 1.90
This is almost a regular structure with dimension 2:
A crumpled sheet!!
Rg PDI 94.0Å 1.08
This is and almost sperical domain of
24.3 nm diameter.
Deviation from PDI = 1 can be due to polydispersity or asymmetry.
Cytochrome C Native State
Space Filling Model
Rg PDI Native 94.0 Å 1.08
MG 99.0 Å 2.90
(Both also
Show Aggregates at Low-q)
Model of cytochrome b562 A) MG B) N
Cytochrome C
Molten Globule State
Alberts B, Bray D, Lewis J, Raff M, Roberts K, Watson JD. Chapter 5: Protein Function. Molecular Biology of the Cell 3rd Ed. Garland Publishing, New York. 1994. pg 213 & 215.
Summary:
-Two classes of branching effects:
persistence and scaling
-Statistical understanding of scaling can distinguish regular and fractal structures statically
-Examples from aggregated ceramics, branched polymers, and proteins.
-The proposed method would seem to have broad applicability
Swiss National Science Foundation, US NSF, Swiss Commission for Technology and Innovation
Polydispersity in aggregate size
( )q Bfqdf
I = -
( ) ÷÷
ø ö çç
è
= æ - exp 3
2 2
Rg
G q q I
M
w/M
n~ 3
Large aggregates
Growth kinetics show d
min=> 1
d
f=> 1.8 for RLCA
Predicted previously
by Meakin
Monodisperse Fractal Aggregates Mw/Mn = 1
Constant Growth Conditions z = 8, 30, 100
dmin is constant, 1.15
Similar to Branched Polymers df increases
c increases
Construction of A Scattering Curve
I() is related to amount Nn2
is related to size/distances
( )
q d 2
sin 2 4
p l
p
=
= q
We can “Build” a Scattering Pattern from Structural
Components using Some Simple Scattering Laws
q = 2 d p I ( q ) = N ( d ) n
e2( ) d
N = Number Density at Size “d”ne = Number of Electrons in “d” Particles Complex Scattering Pattern (Unified Calculation)
Particle with No Interface
( ) d
n d N q
I ( ) = ( )
e2÷ ÷ ø ö ç ç
è
= æ -
exp 3 )
(
2 1 , 2
1
R
gG q q
I
6 2
2
V ~ R
N G = r
e6 8 2
R
~ R R
gGuinier’s Law
Spherical Particle With Interface (Porod)
Guinier and Porod Scattering
)
4( q = B q
-I
PS N
B
P= 2 p r
e2~ R
2S
3 2
2
I ( q ) dq N R
q
Q = ò = r
e2 3
2 R
R B
d Q
P
p
= =
p
Structure of Flame Made Silica Nanoparticles By Ultra-Small-Angle X-ray Scattering
Kammler/Beaucage Langmuir 2004 20 1915-1921
Polydisperse Particles
Polydispersity Index, PDI
G R PDI B
P g62 . 1
4
=
( ) ( )
1212 ln ln
úûù êëé
=
= PDI
g
2 1 14
2
3
25
ú ú û ù ê ê
ë
= é
e m R
gParticle size distributions from small-angle scattering using global scattering functions, Beaucage, Kammler, Pratsinis J. Appl. Cryst. 37 523-535 (2004).
Linear Aggregates
Beaucage G, Small-angle Scattering from Polymeric Mass Fractals of Arbitrary Mass-Fractal Dimension, J. Appl. Cryst. 29 134-146 (1996).
÷ ÷ ø ö ç ç
è
= æ -
exp 3 )
(
2 2 , 2
2
R
gG q q
I
df
R R G
z G ÷÷ ø çç ö
è
= æ
=
1 2 1
2
df
f
q B q
I ( ) =
-( ) 2
2 , 2
d f g
f
f
d
R d B G
f
G
=
( ) 2
2 ,
min
2 d f
g
f
d
R d B G
f
G
= Branched Aggregates
Beaucage G, Determination of branch fraction and minimum dimension of fractal aggregates Phys. Rev.
E 70 031401 (2004).
c d
R z
p R
11 2
min
÷÷ = ø çç ö
è
= æ
df
d
Br
R
R
-÷÷ ø çç ö
è - æ
=
min
1
1
2
d
minc = d
fLarge Scale (low-q) Agglomerates
)
4( q = B q
-I
PSmall-scale Crystallographic Structure
2) Persistence length and substructural scaling
New Idea:
Long-chain branching
Effects chain scaling (df, dmin, c) Short-chain branching
Effects chain persistence (lp and chain entropy, G)
(dendrimers may be an interesting case in this regard)
Old Idea:
Long-range interaction Effects chain scaling (SAW df = 5/3)
Short-range interaction Effects chain persistence (lp and chain entropy, G) Flory RISM, C
Intrinsic and Topological Stiffness in branched polymers. Connolly R, Bellesia G, Timoshenko EG, Kuznetsov YA, Elli S, Ganazzoli G Macromolecules 38 5288-5299 (2005).
Outline:
1) Fractal dimensions and degree of aggregation 2) Persistence length and substructural scaling
3) Minimum number of features 4) Small-angle scattering for branched structures
5) Growth kinetics
for ceramic aggregates 6) Summary
Kammler HK, Beaucage G, Kohls DJ, Agashe N. Ilavsky J J Appl. Phys. 97(2005) (Article 054309).
3) Minimum number of features
http://www.cs.ucl.ac.uk/staff/D.Jones/t42morph.html
a) <Persistence length>: lp or dp b) <z>
c) df mass scaling dimension d) dmin mass scaling for
minimum path, p
e) In some cases you may want the number of branches or the coordination number
With these features you can calculate:
branch fraction, br connectivity, c
regularity of the structure (“disk/rod/sphere” -ness) & compare with simulations
Statistically, there are 2 distinct classes of consequences from branching:
chain persistence and structural scaling
Some Complexities of Fractal Growth
Fractal aggregates are springs
Ogawa K, Vogt T., Ullmann M, Johnson S, Friedlander SK, Elastic properties of nanoparticulate chain aggregates of TiO2, Al2O3 and Fe2O3 generated by laser ablation, J. Appl. Phys. 87, 63-73 (2000).
Fractal aggregates can behave at times as semi-dilute polymers.
Overlap Concentration Tensile Blob
Low Elongation
df
d
BB
E
G
-+
=
33 min
High Elongation
E l
P =
*Witten TA, Rubinstein M, Colby RH,
Reinforcement of rubber by fractal aggregates J. Phys. II France 3 367-383 (1993).
Kohls DJ Beaucage G, Rational design of reinforced rubber Cur. Op. Sol. St. Mat. Sci. 6 183-194 (2002).
df<2dmin df>2dmin weakly
branched strongly branched
-(dmin+df+1) (dmin+1)/(dmin-1)
2(df-1)/(dmin-df+2) -(3dmin+1)/(2dmin-df+1)
df=1.7-1.8 dmin=1.2-1.3
df=2.0-2.1 dmin=1.0-1.1
Polymers vs. Ceramic Aggregates Thermo. Equil. vs. Kinetic Growth
For Polymers dmin is the
Thermodynamically Relevant Dimension (5/3 = 1.67 or 2)
Branch fraction can be defined in this context
Hyperbranched Polymers Closer to Ceramic Aggregates
Kulkarni A, Beaucage G using data from:
Geladé ETF et al. (Mortensen), Macromolecules 34, 3552 (2001).
Data from:
E. De Luca, R. W. Richards, I. Grillo, and S. M. King, J. Polym. Sci.: Part B: Polym. Phys. 41, 1352 (2003).
Comparing simulated growth mechanisms for ceramic aggregates, minimum path, d
min, is the most important structural feature.
Minimum path becomes more convoluted
Chains more branched
Branched Structures
http://www.eng.uc.edu/~gbeaucag/Classes/Properties.html
http://www.eng.uc.edu/~gbeaucag/Classes/MorphologyofComplexMaterials/Overview.html
-Non-space filling
Density is a function of size -Often display fractal scaling Fractal statics, df
Fractal dyamnics, dmin
-Often display a large-scale limit -Always display a small-scale limit -Substructure can also display fractal structure, that is
scaling transitions are possible -What is the minimum number of features needed to describe a branched structure? (This may depend on what you want.)
-2
( )
2 2, min
2 f
f
d d
g
f
R
d
B = G G
Topological information can be extracted from this feature arising from combined Local Scattering Laws
( )
÷ ÷ ø ö ç ç
è
= æ -
exp 3 )
(
2
R
gG q q
I
Guinier’s Law
dff
q B
q
I ( ) =
-Power Law
G Beaucage, Physical Review E (2004)
A S Kulkarni and G Beaucage, Journal of Polymer Science, Part B: Polymer Physics (2006)
( ) 2
2
2 , min
f d g f
d G
R d B
f
= G
Branch content from scattering
df
c
R z R
p ÷÷
ø çç ö
è æ
1
~
2~
1 2
G z = G
d
minc = d
f br d dfR R z
p
z
-÷÷ ø çç ö
è - æ - =
=
min
1
1
2
R2
R1
dmin p
G Beaucage, Physical Review E (2004)
A S Kulkarni and G Beaucage, Journal of Polymer Science, Part B: Polymer Physics (2006)
Figure 11. Schematic of particle nucleation and growth from in situ data analysis.
-Smallest Particle is not
Molecular Scale Predicted by Chemical Nucleation -Homogeneous Nucleation is Observed in Peak in N and Minimum in d
p(~ 1/T)
-Hydrolysis/Condensation Mechanism is Supported -These Low T Flames may differ Significantly from High T Flames
SAXS Summary TiCl
4Flame
Possible explanations for observations
Girshick Model (Giesen) matches data (except in SIZE)
On the interaction of coagulation and coalescence during gas-phase synthesis of Fe-nanoparticle agglomerates Giesen, Othner, Roth (Duisburg-Essen) Chem. Eng. Sci.
59 2201-2211 (2004) & Iron-atom condensation interpreted by a kinetic model and a nucleation model approach Giesen Kowalik Roth Phase Trans. 77 115-129 (2004)