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

More documents

Recommendations

Info

characteristics, due to presence -electron-rich and -poor receptors. Manual cuts made onto the filmswere shown to be healed completely at 90 o C within a short time while at 115 o C, healing was too fast tobe observed (Figure – 1.18b,c,d).Figure – 1.18: Self-healing system based on – olyimideand siloxane polymer bearing pyrenyl end groups, b-d) Unhealed and healed films at 30 o C, 92 o C and 115 o Crespectively 110 .In a further improved work, the authors capitalized on both interpolymer hydrogen bonding and– system exhibited a nanophase separted morphology with well contrasted two different domains. Theauthors reported a reproducible regain of more than 95% of the tensile modulus, 91% of the elongationto break, and 77% of the modulus of toughness of the pristine material for fractured samples healed at100 o C.1.4.1.2 IonomersPolymers consisting of upto 15 % of ionic content in their structure are classified as ionomers. Beingthermoplastic in nature, these polymers contain carboxylic acid moieties as pendant groups which caneither be in partially or completely neutralized state with either a metal or quaternary ammonium ions.Given the dynamic nature of the ionic bonds, it is not surprising that these polymer systems beenexplored recently for the preparation of self-healing materials. One of the most studied ionomers forself-healing application are based on poly(ethylene-co-methacrylic acid) (PEMAA). This ionomer is23
commercialized under tradenames; Nucrel® having 5.4 mol% methacrylic acid, Surlyn® having 5.4 mol%methacyrlic acid but neutralized by metal ion in varying percentages. Both of these ionomers haveshown self-healing behavior upon projectile impact, especially Surlyn® which shows an almostinstantaneous healing. Earlier it was postulated that the healing phenomenon observed in theseionomers is due to their inherent thermally responsive ionic linkages. However this reasoning does notexplains albeit small healing observed in case of Nucrel® which does not contain any ionic aggregates.Furthermore, the projectile puncture in these ionomers was circular in nature with diameter inmillimeters. Therefore, while reptation motions responsible for chains interdiffusion in case of fracturedsurfaces in contact with each other, it is impossible for them to initiate large scale motions required tobring the surfaces together to heal the circular perforation. A later work 112 on the same ionomersshowed that instead of ionic content, it is the presence of an ionic functionality (in the form of acidgroup) that is crucial for the healing process. The authors found that the incorporation of acid groups inthe polymers, imparted thermoresponsive hydrogen bonding and unique viscoelastic response whichwere responsible for the promotion of the healing process. In follow on thermal studies 113 , it was foundthat healing mechanism is strongly dependent upon the sharp increase in temperature at the puncturepoint after projectile impact however higher temperatures did not favored the healing process. Theshape of projectile was also found to be important parameter for the healing response with pointedprojectiles giving better results than blunt ones. In contribution to above findings, similar ballisticstudies 114 combining a modified testing method 115 showed that while the outer impact regions exhibitductile/elastic behaviour, the inner regions to the impact cavity exhibit elastomeric and viscousbehaviour. The presence of ionic clusters imparts various properties from elastic, elastomeric and thenmolten behavior at different temperatures and thus playing a critical role during high-energy impact(Figure – 1.19). Additionally, healing cycles up to 6 were performed demonstrating the inherent natureof healing based on the chemical structure and morphology of the polymer system. Some more recentexamples 116,117 using ionomers include their blends with ethylene-co-vinyl alcohol copolymer (EVA) andepoxidized natural rubber. Although in these works, healing efficiency has not been mentioned explicitly,nevertheless ionomers based materials can be considered highly efficient and completely autonomous interms of healing given the rapid closure of hole created by very fast impact.24
Page 1: THESISPRESENTED ATNATIONAL GRADUATE
Page 4 and 5: As the human civilization progress
Page 6 and 7: CHAPTER - 1 SELF-HEALING POLYMERIC
Page 8: 8.1.5 Atomic Force Microscopy …
Page 11 and 12: Synthetic engineering materials in
Page 13 and 14: esponse to a specific external stim
Page 15 and 16: The first work based on this approa
Page 17 and 18: een prepared from urea-formaldehyde
Page 19 and 20: monomer systems. The addition of EN
Page 21 and 22: Figure - 1.10: Self-healing process
Page 23 and 24: was required to reach healing effic
Page 25 and 26: In addition to above works, some ot
Page 27 and 28: that have been identified to be tak
Page 29 and 30: part of the chapter, these material
Page 31: Figure - 1.17: Self-healing of the
Page 35 and 36: joined together at temperature high
Page 37 and 38: Inspired by these findings, the fir
Page 39 and 40: temperature greater than 80 o C in
Page 41 and 42: Figure - 1.27: Sulfur chemistry bas
Page 43 and 44: A different kind of sulfur chemistr
Page 45 and 46: Figure - 1.29: Dynamic covalent che
Page 47 and 48: cracks. The recovered droplets afte
Page 49 and 50: 23 White, S. R. et al. Autonomic he
Page 51 and 52: 65 Taber, D. F. & Frankowski, K. J.
Page 53 and 54: 107 Kushner, A. M., Vossler, J. D.,
Page 55: 148 Park, J. S., Kim, H. S. & Hahn,
Page 58 and 59: The value of subscripts “n”,
Page 60 and 61: The formation of spherical micelles
Page 62 and 63: the micelle assembly showed the pre
Page 64 and 65: 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 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 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
Page 168 and 169:
ELABORATION OF SELF-HEALING POLYMER
Page 170 and 171:
ELABORATION DES MEMBRANES POLYMERES
show all

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

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?