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1. SELF-HEALING POLYMERIC SYSTEMSNature has been instrumental in inspiration for innovations and discoveries for human kind sincethe predawn era. One can find a whole range of materials ranging from the hardest knownmaterial to innumerable stimuli-responsive systems. These advance complex biological materials areresult of an evolutionary process which started millions of years ago and still continuing. Of all theremarkable features exhibited by these biological systems, the ability to self-heal or regenerate inresponse to damage caused by an external factor is quite intriguing. Organisms like hydra, starfish canregenerate easily even if a large chunk of their body is cut away. In humans, healing process is selfevidentwhen a small wound is healed over the course of time. Human liver is able to wholly regenerateitself from as less as 25%, demonstrating the level of advancement in nature. In biological systems, thehealing process (Figure – 1.1) follows mainly three stages 1 : an inflammatory response to the injurycharacterized by healing material clotting followed by cell proliferation leading to matrix deposition andin the end remodeling of the matrix. The last two steps generally slow and may span over several monthsdepending upon the extent of injury.Figure– 1.1: Biological route for healing process 11
Synthetic engineering materials in general do not have aforementioned healing ability. Most ofthese materials were developed and optimized by the constant need of more robustness, less cost anddurability. However during the course of utilization, a material encounters various kinds of stressesleading to degradation, internal or external damages and finally a catastrophic failure. Consequently,research community has diverted its attention to develop such smart materials which are able to detectdamages and repair themselves accordingly in an autonomous fashion. Such materials are expected tohave longer life and reduced maintenance and life cycle costs. Different kinds of self-healing approacheshave been developed for polymers, metals, concretes 2-6 and ceramics 7 with first class showing themaximum development related to self-healing. The scope of this chapter and work shall also be limitedto polymers and composites in the same sense.1.1 FRACTURE IN POLYMERIC SYSTEMSPolymers used in engineering domain sustain damage via various external factors like thermal,chemical, biological and respective application related stresses. However, for such materials failurescaused by cyclic fatigue and impact are most important and studied 8,9 . When a crack appears in amaterial, its further propagation inside the material is favored when the amount of energy releasedduring cracking is larger or at least equal to the energy required to create new surfaces on the material 10 .The crack propagation modeling is often explained using a certain stress intensity parameter K 11,12 I . Thisparameter depends on crack depth, geometry of both crack and material as well as the stress appliedonto the material in case of crack opening type failure (Figure-1.2).Figure– 1.2: Opening failure in a material of mode-I type 13The crack grows when K I reaches a certain critical value, K IQ due to change in the applied stressand geometry of the crack caused by cyclic or monotonic loads. During an impact damage incident(consisting of a monotonic load) the extent of crack propagation is related to the maximum stress2
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 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 and 32: Figure - 1.17: Self-healing of the
Page 33 and 34: commercialized under tradenames; Nu
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”,
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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 - 3.20). A cursory look at
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When compared to poly(styrene) NPs,
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Page 110 and 111:
REFERENCES1 Metzler, R. & Klafter,
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46 Bemporad, D., Luttmann, C. & Ess
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In this chapter, preparation of 3D
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obtain complex macromolecular archi
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The polymerization was conducted at
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proceeds, lesser monomer is availab
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mg/ml),the micelles’ hydrodynamic
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Figure - 4.15: The monolayer and mu
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monolayer of micelles and topmost l
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The presence of the dispersed micel
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Heating the multilayer micelle asse
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stable zipping of the micelles. Mul
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24 Moad, G., Rizzardo, E. & Thang,
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The concept of nano-gel based self-
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Figure - 5.4: Size distribution of
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In a typical process, the two compo
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Figure - 5.10: 1HNMR spectra obtain
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The 1 HNMR spectrum obtained for th
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REFERENCES1 White, S. R. et al. Aut
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healing ability shown by the membra
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7. PERSPECTIVESBeing the first such
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8. MATERIALS & METHODSThis chapter
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8.1.3 PEG Filtration MeasurementsTh
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addition of TEOS due to formation o
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solution was ultrasonicated for 15
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Triethylamine (TEA) (Sigma-Aldrich
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To prepare the monolayer assembly o
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was added followed by addition of 0
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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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