4(%3)3 - Ecole nationale supÃ©rieure de chimie de Montpellier

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8.1.5 Atomic Force MicroscopyThe AFM images were obtained with Dimension 3100 -Veeco Instruments®. This system of nearfieldmicroscopy used for high resolution imagery was controlled by the Nanoscope IIIA quadrexsoftware. All analyses were carried out in tapping mode allowing the capture of topographic images inrepulsive mode. The tips used in this study were needles with force modulation provided byNanosensors (Pointprobe plus - Silicon SPM sensor, with a resonance frequency of about 60 kHz and K=2N/m). To analyze the morphology change due to pressure after water permeation at a given pressure,the membrane was removed together with the nonwoven fabric and dried in a closed chamber in thepresence of silica gel (oven dried) for 24 hours. Once dry, the membranes were separated from the fabricand manually transferred onto Silicon wafers before AFM analysis.8.1.6 Scanning Electron MicroscopyThe SEM images were obtained using a Hitachi® S-4800 instrument operating at a spatialresolution of 1.5 nm at 15 kV of energy. The samples were dried in a closed chamber in the presenceof silica gel (oven dried) and analyzed without metallization. To obtain 3-Dimensional images,images of the samples taken at different angles and were processed using Alicona® MeX software for3D color rendering.8.2 TRANSLOCATION ACROSS A SELF-HEALING MEMBRANE8.2.1 Membrane Film PreparationThe membrane films were prepared according to the aforementioned procedure.8.2.2 Silica Nanoparticles SynthesisThe synthesis of silica particles was carried out using a modified Stober process 1 . The procedureinvolves the hydrolysis and condensation of triethyl orthosilicate (TEOS) (Sigma-Aldrich®, > 99.9 %) inisopropanol (Sigma-Aldrich®, > 99.99 %)in the presence of ammonium hydroxide. In a general procedure,a 100 ml ultrasonically cleaned round bottom flask (RB) was taken and certain amount of ultrapure water(MilliQ®), Ammonium hydroxide solution (Sigma-Aldrich®, > 99.99 %) and Isopropanol were mixed usinga clean magnetic stirrer for 5 minutes. The RB was closed using a rubber septum and the temperaturewas maintained at 20 o C followed by the addition of a precalculated quantity of TEOS in dropwise mannerby using a calibrated syringe. The transparent solution mixture gradually became opaque by the end of145
addition of TEOS due to formation of silica suspension in the RB. In case of series SP1, the system waskept on stirring at 20 o C for 5 hours after which, the particles were separated from liquid viacentrifugation (12000 rpm, 15 min). The particles were washed 4 times with ultrapure water and ethanol(Sigma-Aldrich®, >99.5 %) successively followed by vacuum assisted overnight drying at 150 o C. In case ofseries SP2, after the addition of TEOS, ultrasonic probe (Amplitude: 40%; Pulse: 5 min on 10 min off) wasused for a period of 1 hour 30 minutes followed by aforementioned washing procedure for SP1 series.The application of ultrasonic probe increases temperature hence to maintain the temperature of the RB,an ice bath was used.The quantity of all the components of the reaction mixture was taken in terms of volume and therelative concentrations of the reactants were according to the following relation:[NH 3 ] = 0.81[TEOS]), [H 2 O] = 6.25[TEOS]The value of [TEOS] was taken to be 0.22 M 1 , calculated by taking the final concentration of TEOS in thereaction mixture. The following Table – 8.1 presents the concentrations and amount of reactants usedfor the synthesis of two series of silica particles used in this work.SilicaParticlesIsopropanol TEOS NH 3 ; NH 4 OH H 2 O Temperatureml moles ml moles ml moles mlo CDistributionSP1 28.5 0.0135 3 0.01088 0.73 0.0839 1.5 20 BimodalSP2 58 0.0224 5 0.01814 1.2 0.1399 2.5 20 BimodalTable – 8.1: Amount of reactants used in the synthesis of silica nanoparticles.8.2.3 Scanning Electron MicroscopyThe SEM instrumentation and its specifications are the same as mentioned in the firstsection. However all the samples excluding the membrane with translocated Poly(styrene) particles,were metalized for 6 minutes prior to analysis. All samples were dried according to the processpreviously mentioned.8.2.4 Atomic Force Microscopy146
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THESISPRESENTED ATNATIONAL GRADUATE
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As the human civilization progress
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CHAPTER - 1 SELF-HEALING POLYMERIC
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8.1.5 Atomic Force Microscopy …
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Synthetic engineering materials in
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esponse to a specific external stim
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The first work based on this approa
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een prepared from urea-formaldehyde
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monomer systems. The addition of EN
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Figure - 1.10: Self-healing process
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was required to reach healing effic
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In addition to above works, some ot
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that have been identified to be tak
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part of the chapter, these material
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Figure - 1.17: Self-healing of the
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commercialized under tradenames; Nu
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joined together at temperature high
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Inspired by these findings, the fir
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temperature greater than 80 o C in
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Figure - 1.27: Sulfur chemistry bas
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A different kind of sulfur chemistr
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Figure - 1.29: Dynamic covalent che
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cracks. The recovered droplets afte
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23 White, S. R. et al. Autonomic he
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65 Taber, D. F. & Frankowski, K. J.
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107 Kushner, A. M., Vossler, J. D.,
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148 Park, J. S., Kim, H. S. & Hahn,
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The value of subscripts “n”,
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The formation of spherical micelles
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the micelle assembly showed the pre
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gain onto the electrodes by buildin
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The resistance R can be further exp
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empty-tower velocity U only depends
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This apparent morphological switchi
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In a further qualitative analysis,
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noteworthy and though its feasibili
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Furthermore within this range, lowe
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Figure - 2.22: Scanning Electron Mi
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While the resistance measurements g
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In conclusion, a self-healing membr
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23 Giacomelli, F. C., Riegel, I. C.
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micelles enabled the membrane to se
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The second class is represented by
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To avoid the probable clogging of t
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181614SP2 - iNumber of Particles121
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1000900800y = 3E+06xR² = 0,9911y =
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very high value of 1.5 g.l -1 . Thi
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Since the only change in the membra
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100Retention (%)8060400,100,20,40,6
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Figure - 3.18: Scanning Electron Mi
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(Figure - 3.20). A cursory look at
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Page 108 and 109: Figure - 3.24: Scanning Electron Mi
Page 110 and 111: REFERENCES1 Metzler, R. & Klafter,
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Page 114 and 115: In this chapter, preparation of 3D
Page 116 and 117: obtain complex macromolecular archi
Page 118 and 119: The polymerization was conducted at
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Page 122 and 123: mg/ml),the micelles’ hydrodynamic
Page 124 and 125: Figure - 4.15: The monolayer and mu
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Page 128 and 129: The presence of the dispersed micel
Page 130 and 131: Heating the multilayer micelle asse
Page 132 and 133: stable zipping of the micelles. Mul
Page 134 and 135: 24 Moad, G., Rizzardo, E. & Thang,
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Page 138 and 139: Figure - 5.4: Size distribution of
Page 140 and 141: In a typical process, the two compo
Page 142 and 143: Figure - 5.10: 1HNMR spectra obtain
Page 144 and 145: The 1 HNMR spectrum obtained for th
Page 146 and 147: REFERENCES1 White, S. R. et al. Aut
Page 148 and 149: healing ability shown by the membra
Page 150 and 151: 7. PERSPECTIVESBeing the first such
Page 153 and 154: 8. MATERIALS & METHODSThis chapter
Page 155: 8.1.3 PEG Filtration MeasurementsTh
Page 159 and 160: solution was ultrasonicated for 15
Page 161 and 162: Triethylamine (TEA) (Sigma-Aldrich
Page 163 and 164: To prepare the monolayer assembly o
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Page 168 and 169: ELABORATION OF SELF-HEALING POLYMER
Page 170 and 171: ELABORATION DES MEMBRANES POLYMERES
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4(%3)3 - Ecole nationale supÃ©rieure de chimie de Montpellier

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