"The objective of this research was to investigate the enzyme-catalyzed functionalization of polymers. For this purpose, first, model small molecules were employed in Candida antarctica lipase B (CALB)-catalyzed transesterification and Michael addition reactions. CALB-catalyzed transesterification of ethyl acetate and vinyl acetate with 2-phenyl-1-propanol (2PPOH), the model compound for primary hydroxyl-functionalized polyisobutylene (PIB) prepared from the [alpha]-methylstyrene epoxide ([alpha]=MSE)/TiCl4 initiator system, indicated that the latter was a more effective acyl donor as it formed unstable vinyl alcohol which instantly tautomerized to acetaldehyde and thus rendered the reaction irreversible. The comparison of the catalytic activity of CALB with that of a commercially available transesterifiction catalyst, bis[dibutylchlorotin(IV_] oxide, revealed that in the transesterification of vinyl acetate with 2PPOH, CALB was the more reactive catalyst. Ethylene glycol (EG) was reacted with vinyl methacrylate (VMA) in the presence of CALB as a model reaction for the methacrylation of poly(ethylene glycol) (PEG) and it was observed that the reaction proceeded in a consecutive fashion first yielding the monosubstituted product followed by disubstituted ester. Thymine was reacted with both vinyl acrylate (VA) and VMA through Michael addition in the presence of CALB as a model reaction for the addition of thymine to (meth)acrylated polymers. Quantitative conversion was observed in the case of VA whereas VMA gave 63% conversion. The resulting vinyl esters of thymine were then reacted with EG through transesterification using CALB as the model reaction for the addition of thymine to hydroxyl-functionalized polymers. It was observed that the majority of the product was the monosubstituted EG. These synthetic procedures were then applied to polymer functionalization. The primary hydroxyl-functionalized PIB prepared from [alpha]-MSE/TiCl4 was not reactive towards CALB. On the other hand, PIBs fitted with 3-hydroxypropyl or 3-hydroxyl-2-methylpropyl-termini gave quantitative conversions with VMA indicating the effect of chain and structure in enzymatic polymer functionalization. CALB-catalyzed enzymatic methacrylation of polymers in the absence of solvents was attempted using polydimethylsiloxanes and low molecular weight PIBs and the enzyme was found to be very effective. PEGs with a variety of molecular weights and molecular weight distributions reacted effectively with VMA in the presence of CALB. The monitoring of the reaction with MALDI-ToF MS revealed the simultaneous presence of PEG, monosubstituted PEG and disubstituted PEG with monosubstituted PEG comprising the majority of the product at the early stage of the reaction. PEGs were also functionalized with thymine via Michael addition to corresponding acrylated PEGs. Amano lipase M from Mucor javanicus was shown to be a more effective catalyst than CALB in this reaction. Alternatively, the CALB-catalyzed transesterification of the vinyl ester of thymine, which was produced by Michael addition of thymine to VA, with poly(ethylene glycol) monomethhl ether (mPEG) also yielded the thymine-functionalized polymer. The attempts to prepare thymine-functionalized PIBs with the same synthetic procedures were not successful. The regioselectivity of CALB was utilized to methacrylate asymmetric [alpha], [omega]-hydroxyl-functionalized PIBs, which were prepared via the [alpha]-MSE/TiCl4 initiator system and subsequent derivatization of the [omega]-termini to hydroxyl groups, exclusively at the [omega]-termini. The enzymatic synthesis of PEG-b-PIB was also attempted. The procedure involved CALB-catalyzed coupling of mPEG with hydroxyl-functionalized PIB by transesterification using divinyl adipate (DVA) as the linker. The reaction was carried out in two steps: transesterification of DVA with mPEG and transesterification of the resulting vinyl ester of mPEG with the hydroxyl-functionalized PIB. In the first step, the effect of DVA concentration and the molecular weight of mPEG on self-coupling of mPEG was also investigated and it was found that the extend of coupling decreased with increase in the DVA concentration and the mPEG molecular weight. In the second step, the formation of diblock copolymer was detected by SEC. CALB-catalyzed transesterification of VMA with EG in bulk was monitored using in-situ FTIR; however, unreliable results were obtained probably due to the saturation of the probe as a result of high concentration of reactants. As a side project, primary hydroxyl-functionalized polyisobutylene prepared by the [alpha]-MSE/TiCl4 initiator system was further functionalized with thymine using conventional catalysts. The synthetic procedure involved Michael addition of thymine onto acrylate-functionalized polyisobutylene which was derived from the hydroxyl-functionalized precursor by esterification with acryloyl chloride. The structure of the product was verified by NMR and MALDI-ToF mass spectrometry."--Abstract.