Control of swelling, electrochemical, and elongation properties of photopolymers through the modification of structure

• Main Author: McLaughlin, Jacob Ryan
• Other Authors: Guymon, C. Allan
• Format: Others
• Language: English
• Published: University of Iowa 2018
• Subjects: forward osmosis; liquid crystals; photopolymerization; reversible addition fragmentation chain transfer; stimuli-reponsive material; structure property relationship; Chemical Engineering
• Online Access: https://ir.uiowa.edu/etd/6205; https://ir.uiowa.edu/cgi/viewcontent.cgi?article=7537&context=etd

Modifying photopolymer structure on the molecular and nanoscale level permits tailoring materials for use in a wide variety of applications. Understanding the fundamentals behind polymer structure at these levels permits the control of material properties. This work gains insight into the modification of structure on two levels, the nanoscale by use of structure templates and the molecular scale through the modification of polymer network formation. Lyotropic liquid crystals (LLCs) are a type of self-assembling surfactant system, which in combination with photopolymerization can be used to template ordered nanostructure within polymer materials. This structure can be controlled and utilized to influence the properties of a polymer material. This research examines materials used as templating agents and the types of nanostructures that may be obtained. Additionally, their effects upon the LLC templating process and material properties is determined. Structured polymers are created using LLC templates in pursuit of materials for use in water purification processes and electrochemical devices. Through a more complete understanding of the fundamentals of the templating process, the work presented here extends the LLC templating technique to a greater variety of materials and applications in the water remediation and energy storage fields. The second portion of this research is the use of reversible addition fragmentation chain transfer (RAFT) to modify photopolymer networks. RAFT agents are utilized to control the propagation reaction to create networks with increased homogeneity between network crosslinks. By increasing the uniformity of the polymer network, increases in polymer elongation and toughness as well as decreases in polymer modulus are observed. The effects of RAFT agent addition on the network formation and the final properties of the photopolymer is examined. By understanding the mechanisms behind this modification technique, photopolymers can be extended into new applications where increased elongation and toughness is valued.