La lecture en ligne est gratuite
Le téléchargement nécessite un accès à la bibliothèque YouScribe
Tout savoir sur nos offres
Télécharger Lire

Wetting induced by repulsive particles, porous membranes and metal coated spheres [Elektronische Ressource] / vorgelegt von Tierno Pietro

108 pages
Wetting induced by repulsive particles,porous membranes andmetal coated spheres.DissertationZur Erlangung des akademischen GradesDoktor der Naturwissenschaften (Dr. rer. nat.)an derUniversit˜at UlmFakult˜at fur˜ Naturwissenschaftenvorgelegt vonTierno PietroUlm, 2005Amtierender Dekan: Prof. Dr. Peter ReinekerErster Referent: Prof. Dr. Werner A. GoedelZweiter Referent: Privat. Doz. Dr. Klaus ThonkeTag der Promotion: 21/11/2005A GemmaTable of ContentsTable of Contents vList of Tables viiList of Figures viii1 General introduction. 11.1 Introduction to Particle Assisted Wetting. . . . . . . . . . . . . . . . . . . 11.1.1 Interfacial energy of a single particle at an interface. . . . . . . . . 21.1.2 Scenarios for the Particle-Assisted Wetting. . . . . . . . . . . . . . 61.2 Outline of this thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 Realization of porous membranes with difierent pore size. 122.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.1.1 Preparation of the porous membranes. . . . . . . . . . . . . . . . . 132.1.2 Statistical analysis of membranes with difierent pore sizes. . . . . . 152.2 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182.3 Experimental part . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 Control of Particle Assisted Wetting by an external magnetic fleld. 223.1 Introduction. . . . . . . . . . . . . . . . . .
Voir plus Voir moins

Wetting induced by repulsive particles,
porous membranes and
metal coated spheres.
Dissertation
Zur Erlangung des akademischen Grades
Doktor der Naturwissenschaften (Dr. rer. nat.)
an der
Universit˜at Ulm
Fakult˜at fur˜ Naturwissenschaften
vorgelegt von
Tierno Pietro
Ulm, 2005Amtierender Dekan: Prof. Dr. Peter Reineker
Erster Referent: Prof. Dr. Werner A. Goedel
Zweiter Referent: Privat. Doz. Dr. Klaus Thonke
Tag der Promotion: 21/11/2005A GemmaTable of Contents
Table of Contents v
List of Tables vii
List of Figures viii
1 General introduction. 1
1.1 Introduction to Particle Assisted Wetting. . . . . . . . . . . . . . . . . . . 1
1.1.1 Interfacial energy of a single particle at an interface. . . . . . . . . 2
1.1.2 Scenarios for the Particle-Assisted Wetting. . . . . . . . . . . . . . 6
1.2 Outline of this thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2 Realization of porous membranes with difierent pore size. 12
2.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.1.1 Preparation of the porous membranes. . . . . . . . . . . . . . . . . 13
2.1.2 Statistical analysis of membranes with difierent pore sizes. . . . . . 15
2.2 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.3 Experimental part . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3 Control of Particle Assisted Wetting by an external magnetic fleld. 22
3.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.2 Polystyrene superparamagnetic particles.. . . . . . . . . . . . . . . . . . . 23
3.3 Observation of the induced wetting. . . . . . . . . . . . . . . . . . . . . . 24
3.4 Quantitative measures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.5 Calculation of the total interaction potential. . . . . . . . . . . . . . . . . 29
3.5.1 Capillary Forces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.5.2 Magnetic Forces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.7 Experimental part . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4 Usingrepulsiveparticlesastemplatesforthepreparationofmembranes
of controlled porosity. 41
4.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.2 Preparation of the membranes. . . . . . . . . . . . . . . . . . . . . . . . . 42
4.3 Spatial distribution of the pores. . . . . . . . . . . . . . . . . . . . . . . . 48
4.4 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4.5 Experimental Section. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
v5 Preparation of micron-sized polymer/metal core/shell particles and
hollow metal spheres. 53
5.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5.2 Preparation of metal coated microspheres. . . . . . . . . . . . . . . . . . . 54
5.2.1 Microspheres by metallic layers of difierent thickness. . . . 55
5.2.2 coated by various alloys. . . . . . . . . . . . . . . . . 57
5.2.3 Hollow metallic spheres. . . . . . . . . . . . . . . . . . . . . . . . . 62
5.3 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
5.4 Experimental part. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
6 Conclusion and Outlook. 68
6.1 Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
6.2 Results and applications.. . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
6.3 Outlook. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
A Image processing and statistical tools. 73
A.1 Image processing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
A.2 Mean nearest neighbour distancehd i. . . . . . . . . . . . . . . . . . . . . 74p
A.3 Pair correlation function g(r) and the static structure factor S(k). . . . . 75
B Magnetic colloids. 77
B.1 Polystyrene superparamagnetic particles.. . . . . . . . . . . . . . . . . . . 77
B.2 Magnetization measurements . . . . . . . . . . . . . . . . . . . . . . . . . 79
B.2.1 Polystyrene superparamagnetic particles . . . . . . . . . . . . . . . 79
B.2.2 Composite core/shell particles. . . . . . . . . . . . . . . . . . . . . 79
C Capillary forces. 81
C.1 Theoretical description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
C.2 Asymptotic values for the forces. . . . . . . . . . . . . . . . . . . . . . . . 83
Bibliography 85
Acknowledgements 94
Curriculm vitae. 95
List of Publications 96
Declaration of Originality 97
viList of Tables
2.1 Properties of the silica particles: d = diameter, – = standard deviation,?
† = electrophoretic mobility, ‡ = zeta potential and ? = particle’s„ p c
conductivity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.1 Magnetic properties for the coated particles and corresponding literature values
for the pure material. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
5.2 Bath compositions and conditions. All the quantities are given in mol/l. . . . . 67
viiList of Figures
1.1 Principle of the Particle Assisted Wetting. . . . . . . . . . . . . . . . . . . . . 2
1.2 Colloidal particle trapped at organic liquid/water interface. . . . . . . . . . . . 3
1.3 Total interfacial energy for a polystyrene particle trapped at an organic liq-
uid/water interface of interfacial tension ? = 0:019 N/m as a function of theo=w
penetration depth in the water phase (the three-phase contact angle is supposed
oflxed at the value of: ? = 77.9 ). . . . . . . . . . . . . . . . . . . . . . . . 4pow
1.4 Variation of the gain in energy of a spherical particle of radius r = 100 nm at an
organic liquid/water interface with the contact angle ?. The blue circles refer to
the gain in energy related to the particle of flg. 1.4. . . . . . . . . . . . . . . . 5
1.5 Expressions of the gain in energy of placing a spherical particle of radius r at an
interface with the corresponding situation. . . . . . . . . . . . . . . . . . . . . 6
1.6 Several possible scenarios of arrangement of an organic liquid and particles on a
water surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.7 Phase diagrams of particle assisted wetting calculated for difierent values of the
spreading coe–cient: s= = 0 (a), s= = -0.02 (b), s= = -0.5 (c), s= aw aw aw aw
= -1 (d). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1 Scheme of the preparation of the porous membranes. . . . . . . . . . . . . . . 13
2.2 SEM images of a porous membrane obtained by using silica particles of 345 nm
diameter. The image on the left shows the membrane deposited on a microscope
grid, while on the right side is an enlargement of the same images in order to see
the pores present inside the membrane. . . . . . . . . . . . . . . . . . . . . . 14
2.3 Series of porous membranes having difierent pore sizes. On the right of each
image are the corresponding Voronoi constructions. The scale bar for all the
imagesis5„m(membranes(a),(b),(d),(e)obtainedwithinthisthesis, membrane
(c) courtesy of Dawid Marczewski). . . . . . . . . . . . . . . . . . . . . . . . 16
viii2.4 Radial distribution function g(r)(a) and static structure factor S(k) (b) of the
various membranes. In both graphs the dotted black line at the bottom refer to
the calculated value for a perfect hexagonal crystal of points. . . . . . . . . . . 17
2.5 Chemical formulas of: (a) TMPTMA, (b) benzoin isobutyl ether. . . . . . . . . 19
2.6 Silica particles having 515 nm (a) 1503 nm (b) diameter. . . . . . . . . . . . . 20
3.1 (a)Polystyrenesuperparamagneticparticles(ESTAPORM1200/20),(b)HRTEM
cross-section of a sup particle. . . . . . . . . . . . . . . . . . . 24
3.2 Hysteresis loop at room temperature of the polystyrene superparamagnetic par-
ticles. The red curve refer to a langevin flt. . . . . . . . . . . . . . . . . . . . 24
3.3 Schematic representation of difierent situations and their experimental realization. 25
3.4 Layersoforganicliquid/particlemixtures,characterizedbyavariationofthearea
per particle and fleld strength (the scale bar is 50 „m). . . . . . . . . . . . . . 27
3.5 Double logarithmic plot of the mean inter-particle distance as a function of the
area per particle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.6 Scheme of a cross section through the particle embedded in the liquid layer. . . . 31
3.7 Total capillary force between two particles embedded in a thin fllm as a function
of the inter-particle distance L and calculated at various heigh h of the fllm (the
red line refer to h = 0.6 „m). . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.8 (a) Magnetic moment of a polystyrene paramagnetic particles: the circle are for
fleld lower than 31 mT, black circle for higher fleld while the blue line is a flt. (b)
Magnetic potential between two particles at difierent fleld strength. . . . . . . . 34
3.9 (a) Capillary (dot) and magnetic (dash) contribution to the total interaction
potential (continuous) between two particles embedded in an layer of organic
liquid; (b) total interaction potential for various magnetic fleld strengths. . . . . 36
3.10 Experimental mean distance (from flg. 3.5) of difierent area per particles values
plotted as a function of applied fleld. The continuous line was calculated from
eq. 3.5.10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.11 Magneticparticlesprotrudingfromthebottomofa»4„mthicklayerofTMPTMA
oon water surface. The observation angle was» 45 for both images. . . . . . . . 40
3.12 MagneticparticlesstabilizedataTMPTMA/airinterface. Theobservationangle
owas» 45 for both images. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4.1 Scheme of the preparation of the porous membranes. . . . . . . . . . . . . . . 43
ix4.2 SEM images of a porous membrane before the dissolution of the embedded parti-
cles at difierent magniflcations. The images goes from left to the right and from
top to the bottom. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
4.3 Difierent SEM images of porous membranes realized with an area per particle
2of 77.4 „m and an amount of organic liquid enough to obtain a 600 nm layer.
Fig. 4.3a: overview of a piece cut out of the membrane, flg. 4.3b: a cross-section
of the membrane after the particle dissolution. Fig 4.3(c) and 4.3(d): top view
( 4.3(c)) and bottom view ( 4.3(d)) of the same membrane before the dissolution
of the particles, flg 4.3e and 4.3(f): top view ( 4.3(e)) and bottom view ( 4.3(f))
after the dissolution process. . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
4.4 SEM images (top view) of porous membranes with areas per particle of (a): 7.1
2 2 2 2„m , (b): 23.8 „m , (c): 77.4 „m , (d): 123.7 „m . The diagrams on the right
side of the pictures show the corresponding pair correlation functions g(r) of
the pore positions (continuous red line) and the corresponding g(r) for a per-
fect hexagonal pattern (dotted black line). The corresponding values of hdi are
indicated by blue arrows. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
4.5 Double logarithmic plot of the mean inter-particle distance as a function of the
areaperparticle. Thestraightredlineshowsthebehaviourexpectedforahexag-
onally ordered structure of maximum separations. . . . . . . . . . . . . . . . . 47
4.6 Scheme of the experimental setup. . . . . . . . . . . . . . . . . . . . . . . . . 51
5.1 Schematic representation of the general procedure used to prepare the polymer
microspheres coated with a metallic shell. . . . . . . . . . . . . . . . . . . . . 54
5.2 Series of SEM images showing: a) PMMA particles used as core, b) PMMA
particles coated with a NiP layer (low P coating, bath of Table 5.2), obtained
after 10 min of immersion times in the plating bath; c) after 20 min; d) after 30
min;tope)diagramofthemetallicthicknessasfunctionoftheplatingtime(black
squares: thickness obtained from TEM images; red circles: thickness calculated
from TGA measurements); f) to h) corresponding TEM images of cross-section
of the particles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.3 Characterization of PMMA particles coated with various plating procedures (see
table 5.2). From top to bottom row: NiP1, NiP2, NiFeP, CoP, CoNiP, CoFeP;
from left to right: SEM, TEM, EDAX, magnetization loop of each of the sample. 58
x

Un pour Un
Permettre à tous d'accéder à la lecture
Pour chaque accès à la bibliothèque, YouScribe donne un accès à une personne dans le besoin