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obtain complex macromolecular architectures 26,27 without much hassle. The key component of thistechnique is the transfer agent, specifically termed as RAFT agent which is usually a thiocarbonylthiocompound (Figure – 4.3). The nature of groups “Z” and “R” in a RAFT agent are governed by the type ofmonomer to be polymerized, polymerization conditions and the desired functionalities of the finalproduct.Figure – 4.3: General chemical structure of thiocarbonylthio compoundIn general, the nature of Z group primarily affects the stability of the S=C bond and the stabilityof the P n – S – C (Z) – S – P m radical adduct, thus indirectly affecting the position of and rates of theelementary reactions in the initiation step and the overall main-equilibrium reactions (Figure – 5.4).Figure – 4.4: The main-equilibrium reactions of Reversible Addition Fragmentation Transfer PolymerizationA Z group bearing electron withdrawing component in it, is the preferred choice for improvedtransfer constant but this can also have implications for side reactions 28 . Meanwhile, the R group mustbe a good hemolytic leaving group in comparison to P n so as to favor the right hand side of the initiation106
step, but reactive enough to reinitiate a new polymer chain 28 . The sensitivity of these two groupstowards the monomer and the temperature to be employed for the polymerization further affects theproper selection 29 .SC H 3SC H 3NFigure – 4.5: Chemical structure of 2-Cyano-2-propyl benzodithioateIn the present case, a dithioester was employed for the polymerization of MMA as a RAFT agent.This dithioester; 2-Cyano-2-propyl benzodithioate (Figure – 4.5) is an efficient transfer agent for thepolymerization of MMA with well established kinetics 29 .Figure – 4.6: 1 HNMR of Poly(methyl methacrylate) prepared via RAFT polymerization107
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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
Page 66 and 67: The resistance R can be further exp
Page 68 and 69: empty-tower velocity U only depends
Page 70 and 71: This apparent morphological switchi
Page 72 and 73: In a further qualitative analysis,
Page 74 and 75: noteworthy and though its feasibili
Page 76 and 77: Furthermore within this range, lowe
Page 78 and 79: Figure - 2.22: Scanning Electron Mi
Page 80 and 81: While the resistance measurements g
Page 82 and 83: In conclusion, a self-healing membr
Page 84 and 85: 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 104 and 105: (Figure - 3.20). A cursory look at
Page 106 and 107: When compared to poly(styrene) NPs,
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 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 136 and 137: The concept of nano-gel based self-
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
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ELABORATION OF SELF-HEALING POLYMER
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ELABORATION DES MEMBRANES POLYMERES
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4(%3)3 - Ecole nationale supÃ©rieure de chimie de Montpellier

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