Synthesis and characterization of diblock and triblock copolymers that can be used as templates for nanoporous materials

Block copolymers are known to micro-phase separate into different ordered structures such as lamellae, spheres and cylinders. Such morphologies can be used to template nano-porous materials for membranes and catalyst supports by selective etching of one of the blocks after ordering of the block copolymers. This thesis focuses on the synthesis of polymers that can be used to template nano-porous materials. Poly(styrene)-b-poly(lactide) diblock copolymers and poly(lactide)-b-poIy(styrene)-b-poly(t-butyl styrene) triblock copolymers were synthesized using nitroxide mediated polymerization (NMP) and ring opening polymerization (ROP).;NMP was done with a hydroxyl functional initiator (Vazo-86) to produce a hydroxyl terminated poly(styrene) which was subsequently used as a macro-initiator to perform ROP of lactide catalyzed by triethylaluminum. The kinetics and "livingess" of NMP with this initiator was also studied.;Oligomers of hydroxyl terminated poly(styrene) (weight average molecular weight = Mw =1.5 kg/mole) were used to make diblocks consisting of poly(styrene) and poly(lactide) by ROP and these were then used as macroinitiators for NMP to synthesize triblocks consisting of poly(t-butyl styrene), poly(styrene) and poly(lactide). Molecular weight distributions were narrow (Mw/Mn < 1.3) (where Mn is the number average molecular weight) and careful purification of the macroinitiator was necessary for effective ROP. After alignment by reciprocating shear and degradation of poly(lactide), the diblocks and triblocks are ready for testing for ion exchange capacity.;Poly(styrene)-b-poly(lactide) polymers were made using a commercially available hydroxyl terminated polystyrene and reacting it with triethylaluminum to form a macroinitiator for ROP. This macroinitiator was then reacted with d,l-lactide to form a poly(styrene)-b-poly(lactide) diblock. These diblocks were then partially sulfonated (∼35%) to impart anionic functional groups on the pore walls after selective etching of the poly(lactide) block.