Large-area Coating and Patterning of Functional Nanocomposites: Design, Synthesis and Characterization
2014-02-24T00:00:00Z (GMT) by
Polymer nanocomposite (NC) synthesis from processing of polymer/nanoparticle dispersions remains an active area of research today due to its ability to create nanomaterials using large-area techniques. The benefits of nanomaterials are well documented; however, specific applications remain limited due to their poor durability and scalability. Durability is the tendency of NCs to retain their desirable properties. Scalability is the ability of a given synthesis technique to be implemented at a manufacturing-level. So while large-area processing of superhydrophobic (SHPo) coatings from spray deposition of polymer/nanoparticle dispersions is well documented, most established processes require the use of organic solvents and fluorinated polymers, which raises issues of cost and safety, and in turn, limiting their commercial implementation and scalability. This thesis presents a methodology for generating a SHPo coating from a non-fluorinated, water-based dispersion, eliminating processing hazards. The durability of the SHPo NCs is a major problem impeding commercial implementation. Surfaces typically become compromised through fouling or mechanical failure. This thesis reports wettability studies on two classic, robust NCs. The effect of final composition of NCs on mechanical durability, wettability, and electrical conductivity is considered. The work also investigates failure modes of NCs undergoing mechanical strain and the associated effects on coating wettability. A methodology is presented for dramatically reducing the required filler concentration for achieving superhydrophobicity; ultimately, mechanical properties are enhanced. Surfaces with heterogeneous wettability—so-called patterned wettability (PW)—are also of importance. PW finds applications in pool boiling and lab-on-a-chip; however, previous work emphasized handling water (high surface tension). A methodology for synthesizing a PW coating capable of handling lower surface tension liquids is presented; applications are in combinatorial chemistry. Other PW surfaces—presented in this thesis—were also shown to play an important role in droplet impact and volumetric shaping. Finally, this thesis aims to develop large-area PW surfaces for pool boiling applications; previous work was non-scalable. The work demonstrates the potential of large-area wet processing of NCs for advancing many technologies that require efficient fluid management.