59th Annual Report on Research 2014

Many of us can recall the experience of walking freely and unfettered in an outdoor environment just prior to entering a crowded, confined room. The resultant crowding puts severe restrictions on movement and generally changes the posture and behavior that is possible. This is how Dr. Jodie Lutkenhaus at Texas A&M University describes her research on polymers in confined spaces. Polymers, which are high molecular weight organic chemical compounds, typically possess dimensions on the same length scale as nanoscale particles and pores. When placed into a pore with nanoscale dimensions, a polymer molecule can become confined or restricted in its dynamics and configuration as compared to a polymer molecule in the bulk or solution phase. At a certain critical length of confinement, the polymer behaves quite differently and this results in measurable property differences. Dr. Lutkenhaus, along with her graduate student, Dariya Reid, have been performing research on confined polymers, supported by a grant from the ACS Petroleum Research Fund. The success of the research has already led to two peer reviewed journal publications. In addition, Lutkenhaus has been able to meet and interact with many other researchers who are also interested in confined polymers. Ms. Reid has obtained her master's degree with this support and is currently continuing on to the doctoral degree.

Although confinement of polymers in thin films has been studied in considerable detail, confinement into cylindrical pores has been studied to a much lesser extent. Dr. Lutkenhaus has become very interested in the phenomenon of one dimensional crystallization. Under the right experimental conditions, a semicrystalline polymer can appear to crystallize with orientation in alignment with the pore in which it is confined. Dr. Lutkenhaus also finds it encouraging that new properties can be exhibited by a very traditional, widely used polyolefin such as polypropylene.

The researchers also found that confinement causes the polymers to exhibit changes in melt temperature or in glass transition temperature. Because of the relatively high interfacial area present in these systems, the surface energy of the template in which the pore exists was highly influential in the properties that were measured. Dr. Lutkenhaus' research group also found a very critical pore diameter length at which the properties change quite significantly.

Lutkenhaus has been inspired to continue the work, particularly studying the phenomenon of one-dimensional crystallization in nanoscale pores. “This grant allowed me to start a whole new line of research in my lab,” says Lutkenhaus, “because at the time as I was coming into my faculty position at TAMU my expertise was primarily in layer-by-layer assembly.” Due to the success of the research and the increased familiarity with the field, Dr. Lutkenhaus plans to seek sustaining funding in this area.

Grant #51049-DNI7: Read Lutkenhaus's Annual Report