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<p style="margin: 0in; font-family: Calibri, sans-serif; font-size: 11pt;"><span style="font-family: Arial, sans-serif; font-size: 13.5pt; color: black;"><img alt="Dissertation Defense Announcement at the Cullen College of Engineering" id="x_Picture_x0020_3" width="600" height="170" style="width: 6.25in; height: 1.7812in; margin-top: 0px; margin-bottom: 0px;" data-outlook-trace="F:1|T:1" src="cid:image001.png@01DAD6D7.71807E50"></span></p>
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<span style="font-size: 18pt; color: rgb(200, 16, 46);"><b> </b></span></p>
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<span style="font-size: 18pt; color: rgb(200, 16, 46);"><b>ORDERING OF BLOCK COPOLYMER THIN FILMS WITH ENHANCED DYNAMICS USING SOLVENT PROCESSING AND IONIC LIQUID ADDITIVES</b></span></p>
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<span style="font-size: 13.5pt; color: black;"><b>Kshitij Sharma</b></span></p>
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<span style="font-family: Arial, sans-serif; font-size: 10.5pt; color: black;">July 17, 2024; 10:00 AM – 12:00 PM</span></p>
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<span style="font-family: Arial, sans-serif; font-size: 10.5pt; color: black;">Location: AERB, Room: 320</span></p>
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<span style="font-family: Arial, sans-serif; font-size: 10.5pt; color: black;"><b>Committee Chairs:</b><br>
Alamgir Karim, PhD</span></p>
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<span style="font-family: Arial, sans-serif; font-size: 10.5pt; color: black;"><b>Committee Members:</b><br>
Jacinta C. Conrad, Ph.D. | Jeremy Palmer, Ph.D. | Devin L Schaffer, Ph.D |</span></p>
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<span style="font-family: Arial, sans-serif; font-size: 10.5pt; color: black;">Jack F Douglas, Ph.D</span></p>
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<span style="font-family: Arial, sans-serif; font-size: 12pt; color: rgb(200, 16, 46);"><b>Abstract</b></span></p>
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<span style="font-family: Arial, sans-serif; font-size: 10.5pt; color: black;"> Block copolymers (BCP) self-assemble into a variety of microstructures defined by the entropic and enthalpic interactions between blocks and with the confining surfaces, as
well as their annealing/processing environment. The annealing conditions impact the kinetics of assembly as well as the ordered microstructure and can be different between different techniques. While thermal annealing (TA) exposes the material to heat, other
methods like solvent vapor annealing (SVA) and direct immersion annealing (DIA) expose the polymer to a swelling solvent in vapor and liquid state, respectively. Typically, solvent based methods have faster kinetics due to extensive plasticization of the BCP.
It can be generally expected that adding more complexity to the processing conditions, say, by combining two or more of these annealing techniques or adding a third component to the BCP system, can further alter the thin film's interactions, ordering kinetics,
and morphology evolution.</span></p>
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<span style="font-family: Arial, sans-serif; font-size: 10.5pt; color: black;"> With this research we explore how process design can control the self-assembly process by using a sequential combination of different annealing methods. We first study a sequential
DIA/SVA + TA process where we find synergies between DIA/SVA and TA microstructures leading to rapid ordering into an equilibrium morphology. The reverse process of TA + DIA/SVA exposes the BCP system to highly non-equilibrium conditions that produce surface
instabilities leading to large surface area transition morphologies not observed for BCP films before. Interestingly, with sufficient time of annealing for each step in both forward and reverse processes, the system overcomes any transient morphology and displays
complete microstructure reversibility.</span></p>
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<span style="font-family: Arial, sans-serif; font-size: 10.5pt; color: black;"> We further explore the development of BCP microstructure in the presence of an ionic liquid (IL) additive. ILs can plasticize BCP systems and alter interactions between blocks
and with the substrate. We demonstrate a film casting method that uses a mixture of solvents and IL to dissolve the BCP and order the film in the casting process. The method produces tunable microstructures oriented perpendicular to the film surface on unmodified
substrates. We further show that changing the solvent mixture for dissolving the polymer leads to different as-cast morphologies which can be annealed thermally or in solvent to develop various other non-equilibrium morphologies.</span></p>
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<p style="margin: 0in; font-family: Calibri, sans-serif; font-size: 11pt;"><span style="font-family: Arial, sans-serif; font-size: 13.5pt; color: black;"><img alt="Engineered For What's Next" id="x_Picture_x0020_4" width="600" height="81" style="width: 6.25in; height: 0.8541in; margin-top: 0px; margin-bottom: 0px;" data-outlook-trace="F:1|T:1" src="cid:image002.png@01DAD6D7.71807E50"></span></p>
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