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

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The concept of nano-gel based self-healing system is based on an earlier preliminary workcarried out in the lab by coworker, in which partially crosslinked hydrogels were prepared and theirswelling characteristics were studied. The hydrogels were prepared from RAFT mediated controlledradical copolymerization of 2-hyrdoxyethyl methacrylate (HEMA) and Poly(ethylene glycol)dimethacrylate (PEGMA). In the first step, the hydrogels were prepared in the bulk form to study theeffect of PEGMA chain length on the swelling rate. The obtained hydrogels showed rapid swellingcharacteristics with observable dependence upon the molecular weight of PEGMA which acts as acrosslinker of the gel (Figure – 5.1).Figure – 5.1: Swelling ration of different hydrogels prepared and the corresponding crosslinking agent with %.Figure – 5.2: Swelling ratio of micro hydrogel compared with bulk hydrogel. Optical photos of dry micro hydrogeland swelled micro hydrogel126
In order to be dispersed into a material, the hydrogel must be prepared as microparticles. Toachieve this, inverse suspension technique was utilized which allowed to obtain hydrogel particles havinga broad size distribution but average diameter lesser than 1 µm. When the swelling curves are comparedwith that of bulk hydrogel, the micro hydrogel demonstrated a very high rate of swelling, reaching 70 %water uptake within few minutes as compared to bulk hydrogel which took more almost 200 minutes togain the same amount of water (Figure – 5.2).The above findings points that the as the size of hydrogel particles is reduced, theiroverall swelling characteristics is amplified several folds. In order to further reduce the size of thehydrgels, inverse miniemulsion technique was used, which further reduced average particle size to 300nm (Figure – 5.3). However, further decrease in the size could not be reached in spite of varying differentparameters like surfactant amount, ultrasonication time, temperature, etc. Additionally, the size of theparticles gradually increased over time leading to eventual coagualation. However as expected, thereduced sized particles showed even faster swelling than suspension prepared particles (Figure – 5.4).Figure – 5.3: Size distribution of nano hydrogel prepared using miniemulsion technique.127
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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.
Page 86 and 87: micelles enabled the membrane to se
Page 88 and 89: The second class is represented by
Page 90 and 91: To avoid the probable clogging of t
Page 92 and 93: 181614SP2 - iNumber of Particles121
Page 94 and 95: 1000900800y = 3E+06xR² = 0,9911y =
Page 96 and 97: very high value of 1.5 g.l -1 . Thi
Page 98 and 99: Since the only change in the membra
Page 100 and 101: 100Retention (%)8060400,100,20,40,6
Page 102 and 103: Figure - 3.18: Scanning Electron Mi
Page 104 and 105: (Figure - 3.20). A cursory look at
Page 106 and 107: When compared to poly(styrene) NPs,
Page 108 and 109: Figure - 3.24: Scanning Electron Mi
Page 110 and 111: REFERENCES1 Metzler, R. & Klafter,
Page 112 and 113: 46 Bemporad, D., Luttmann, C. & Ess
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
Page 120 and 121: proceeds, lesser monomer is availab
Page 122 and 123: mg/ml),the micelles’ hydrodynamic
Page 124 and 125: Figure - 4.15: The monolayer and mu
Page 126 and 127: monolayer of micelles and topmost l
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,
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 and 156: 8.1.3 PEG Filtration MeasurementsTh
Page 157 and 158: addition of TEOS due to formation o
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
Page 165 and 166: was added followed by addition of 0
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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