Three homogeneous polystyrene-block-polyisoprene (SI diblock) copolymers with varying block length ratios (SI-10/6, SI-5/6, and SI-14/3) were synthesized via anionic polymerization in tetrahydrofuran as solvent, giving rise to the microstructures of polyisoprene (PI) block of 34,( 1,2-addition, 59% 3,4-addition, and 7% 1,4-addition. Subsequently, the SI diblock copolymers were subjected to hydroboration/oxidation reactions to yield hydroxylated SI diblock (SI-OH) copolymers (SI-10/6-OH, SI-5/6-OH, and SI-14/3-OH). After the hydroxylation, the molecular weight of SI-OH is increased by 3-9% depending on the block length ratio of the corresponding SI diblock copolymer. Infrared (IR) spectroscopy has shown that the SI-OH diblock copolymers form hydrogen bonding at room temperature. Transmission electron microscopy has revealed that at room temperature SI-10/6-OH and SI-5/6-OH have lamellar microdomains while SI-14/3-OH has hexagonally packed cylindrical microdomains. Oscillatory shear rheometry has indicated that the order-disorder transition (ODT) temperature (T-ODT) of SI-14/3-OH is about 195 degreesC, while the T-ODT of SI-5/6-OH and SI-10/6-OH is much higher than 220 degreesC, the highest experimental temperature employed. In-situ IR spectroscopy has indicated that the strength of hydrogen bonding in SI-OH diblock copolymer decreases with increasing temperature. Specifically, it has been found that the hydrogen bonding in SI-14/3-OH virtually disappears as the temperature is increased to 200 degreesC, which coincides with the value of T-ODT determined from oscillatory shear rheometry. On the other hand, in-situ IR spectroscopy has indicated that hydrogen bonding in SI-5/6-OH and SI-10/6-OH still persists as the temperature is increased to 220 degreesC, the highest experimental temperature employed. The above observations lead us to conclude that the ODT induced by the hydroxylation of homogeneous SI diblock copolymers is associated with the presence of hydrogen bonding in the SI-OH diblock copolymers. Segmental interactions between PS and hydroxylated polyisoprene (PI-OH) were investigated via cloud point measurement, for which low-molecular-weight polystyrene (PS) and polyisoprone (PI) were synthesized, and the PI was hydroxylated to yield PI-OH with varying degrees of hydroxylation. It has been found that the extent of repulsive segmental interactions between PS and PI-OH increases as the degree of hydroxylation of PI increases.