| Structures of synthetic and natural polymers were studied in this work. This thesis is divided into two parts.; In the first part, morphology and crystal structures of aromatic polyesters, including poly (2,6-naphthalene terephthalate) and poly (2,6-naphthalene naphthalate) were studied using electron microscopy, electron diffraction and Cerius 2 molecular simulation. A unit cell for each polymer was proposed. The simulated electron diffraction patterns based on the proposed unit cells agree well with the observed patterns.; In the second part, the molecular composition, size and conformation of zein, corn prolamines, was examined with MALDI-MS, TEM, SEC3, SAXS and viscometry. MALDI-MS is demonstrated to be a superior technique to study the molecular weight and composition of zein proteins than conventional SDS-PAGE. The observed large particle size from TEM and SEC3 compared to the predicted value from the molecular weight suggested that zein tends to form oligomeric structures. The denaturation behavior of zero was also studied using various denaturants. The results showed most denaturation agents, such as pH, guanidine hydrochloride and DTT, didn't denature zein. Temperature and SDS may cause some denaturation as suggested from the increase of the intrinsic viscosity; the change of intrinsic viscosity was not sufficient to indicate coil-like conformation. |
