Synthesis of Well-Defined Reactive End- and Mid-Functional Polystyrene by Atom Transfer Radical Polymerization

Abstract

Functional groups increase the utility of polymers and are fundamental to the development of many aspects of structure-property relationships. Reactive end- and mid-functionality play an important role in the properties of polymers and they allow the polymer to couple with other functionalities forming graft, blocks, cross-linking. Control over the synthesis of blocks and grafts the polymer architectures has become increasingly important in producing high value added materials for nanotechnology, biomaterials, blend modifiers and improving particular polymer properties by self-assembly. The end- and mid-functional polymers can be prepared by modifying end- and mid-group of polymers or most conveniently, by using functional initiators in living/controlled polymerization. Recently a method of living/controlled radical polymerization, atom transfer radical polymerization (ATRP) is versatile enough to synthesize end- and mid-functional polymers by using functional initiators. Various α-haloesters have been successfully employed for Cu(I) mediated ATRP to synthesize functional polymers. Structural adjustment of the initiator provides a handle to fine-tune the rate of initiation in the ATRP system and functionality of end- and mid-group. Therefore, in this study, five new α-bromoester initiators bearing allyl, alkyne and dioxolane groups were synthesized and the polymerizations of styrene were carried out with Cu(I)-bypridine mediated ATRP by using those initiators for synthesis of polystyrene containing end- and mid-functionality. This thesis includes seven chapters. The content of each chapter is as follows: In chapter I, general introduction including literature review and objective of this research were discussed. In chapter II, initiator N-allyl-2-bromopropinamide (N-ABPN) was synthesized and the structure of N-ABPN was characterized by 1H and 13C NMR analysis. The efficiency of N-ABPN as initiator on Cu(I)-bipyridine mediated ATRP of styrene were studied at various reaction conditions. The molecular weight and molecular weight distribution of the polystyrene were determined by gel permeation chromatography (GPC). The structure of the polystyrene obtained with N-ABPN was characterized by NMR analys In chapter III, synthesis and characterization of an initiator undecenyl-2-bromopropionate (UBP) was discussed. The efficiency of UBP as initiator on Cu(I)-bipyridine mediated ATRP of styrene were studied at various reaction conditions. The molecular weight and molecular weight distribution of the polystyrene were determined by gel permeation chromatography (GPC). The structure of the polystyrene obtained with this catalyst system was determined by NMR analysis. In chapter IV, synthesis and characterization of an initiator 2-bromo-2-methyl-propionic acid 4-hydroxy-but-2-ynyl ester (BPE) and 2-bromo-2-methyl-propionic acid 4-hydroxy-but-2-ynyl diester (BPDE) were discussed. In chapter V, the efficiency of 2-bromo-2-methyl-propionic acid 4-hydroxy-but-2-ynyl ester (BPE) as initiator on Cu(I)-bipyridine mediated ATRP of styrene were studied at different time duration. The molecular weight and molecular weight distribution of the polystyrene were determined by gel permeation chromatography (GPC). The structure of the polystyrene obtained with this catalyst system was determined by NMR analysis. In chapter VI, the efficiency of 2-bromo-2-methyl-propionic acid 4-hydroxy-but-2-ynyl diester (BPDE) as initiator on Cu(I)-bipyridine mediated ATRP of styrene were studied at different time duration. The molecular weight and molecular weight distribution of the polystyrene were determined by gel permeation chromatography (GPC). The structure of the polystyrene obtained with this catalyst system was determined by NMR analysis. In chapter VII, initiator 2-bromopropionyl[2,2-dimethyl-1,3-dioxolane-4- ylmethyl]ester (BPDME) was synthesized and characterized by spectral analysis. The polymerization of styrene was investigate by Cu(I)-bipyridine mediated ATRP using BPDME as initiator at various reaction conditions. The molecular weight and molecular weight distribution of the polystyrene were determined by gel permeation chromatography (GPC). The structure of the polystyrene obtained with BPDME was characterized by NMR analyses. Finally the end dioxolane group was converted to end-dihydroxyl group by Chemical reaction and the product was characterized by NMR analysis. In chapter VIII, the results obtained in this study were summarized.