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Specific recognition and catalysis are key features of enzymes. Using artificial molecules to mimic the function of enzymes, allows chemists to understand their behavior, and to design an enzyme-like devices. Herein, the novel physical, catalytic and recognition properties of a series of pumpkin-shaped macrocycles named cucurbit[n]urils (CB[n]) were evaluated by spectroscopic methods including 1D and 2D NMR, HRMS, UV-Visible and TEM. We assessed the self-sorting systems incorporating multiple-CB[n] units and a spermine derivative; we studied the stabilization of gaseous fluorotrimethylsilane and designed a fluoride-controlled molecular switch; we also examined the regio- and diastereoselective encapsulation of a series of di- and tribenzylammonium cations and showed how CB[n]s could freeze selected conformations. Finally, CB[n]s were found to catalyze intramolecular Diels-Alder reactions by up to 2500-fold, and a silver-promoted desilylation by up to 6.6-fold. These macrocycles could also stabilize silver nanoparticles and control their size distribution.

A preform glass fiber drawing apparatus is designed and built to investigate non-isothermal viscoelastic glass fiber drawing. The effect of the drawing parameters on glass fiber properties is studied experimentally and analytically. Birefringence is a measure of anisotropy in glass structure that can influence fiber properties and performance. Birefringence is produced during fiber drawing as the fiber is rapidly stretched in the viscoelastic glass transition range, and is frozen into the glass during rapid cooling. With our drawing apparatus using Borosilicate glass (Corning code 7740) preforms, we produce glass fibers for a range of process conditions and measure their as-drawn birefringence. The development of birefringence in glass fibers is found to depend on the amount of deformation, the deformation rate, and temperature. Results for various process parameters show that increasing draw ratio, increasing elongation rate, and decreasing draw temperature increase birefringence. Post-process annealing is used to examine the time and temperature dependence of glass fiber birefringence relaxation and its effect on glass fiber tensile strength. Birefringence is found to completely relax in the temperature range close to the glass transition range as expected, but it is also noted that birefringence shows substantial (although incomplete) relaxation in a temperature range well below the glass transition. This low temperature relaxation indicates that the relaxation process is due to a very wide distribution of relaxation times. A nonisothermal one-dimensional model is examined to simulate the glass fiber drawing and fiber birefringence relaxation using a generalized Jeffrey model. The relaxation time and retardation time are both functions of the temperature. The conservation equations of mass, momentum and energy are solved simultaneously with the viscoelastic constitutive equation to determine the spatial distribution of fiber dimensions, velocities, stresses and frozen in elastic strains. The effects of process parameters on the fiber properties are simulated. The model predictions are compared with the experiments and are found to be in qualitative agreement with data.