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Synthesis and characterizations of (N-hydroxy succinimide methacrylate)-based polymeric materials
Author
Pock, Eriee
Supervisor
Gan, Leong Huat
Abstract
This thesis describes the synthesis and characterization of an useful active ester poly(N-hydroxysuccinimide methacrylate) poly(NHSM), its copolymers and derivatives. The thesis consists of four chapters.
Polymerizations of well-defined homopolymer of N-hydroxysuccinimide methacrylate (NHSM) and copolymer poly [DMAEMA-b-(styrene-r-NHSM)] via atom transfer radical polymerization (ATRP) technique are described in Chapter 1. Well-controlled ATRP of NHSM was achieved using a combination of a Schiff base ligand N-benzyl-2-pyridylmethanimine (NBPM) and CuCl as catalyst. By using poly(DMAEMA) as macro initiator and CuBr as catalyst, poly(NHSM) obtained retained its active end group. This was demonstrated from the successful block copolymerization with NHSM and styrene, forming a water insoluble copolymer poly[DMAEMA-b-(styrene-r-NHSM)]. Poly(NHSM) and poly[DMAEMA-b-(styrene-r-NHSM)] were characterized using GPC, FT-IR and 1H NMR.
The active ester groups of poly(NHSM) react with a variety of amines to produce a range of well-defined poly(methacrylamides), some of which would have been difficult to obtain by direct polymerizations of the methacrylamide monomers. The reaction with various amines and the characterization of the poly(methacrylamides) formed are described in Chapter 2. It was found that complete conversion to poly(methacrylamide) was achieved only with unhindered primary amines, including 4-amino-methyl pyridine, 2-tetradecyl amine, 1-amino- 4-methylpiperazine and benzyl amine. On the other hand, substitution reactions with aromatic amines such as 2,3,5,6-tetrafluoro-4-(trifluoromethyl) aniline, 7- amino-4-methyl-coumarin and aniline did not occur under normal reaction conditions. All poly(methacrylamides) formed retained the same degree of polymerization (DP) and PDI.
To understand the conjugation reaction better, a detailed kinetic study of reaction between poly(NHSM) and 4-amino-methyl pyridine in solution is presented in Chapter 3. The kinetic study was conducted using FT-IR spectrophotometric method. The reactions were carried out under pseudo-first order conditions, in which the amount of amine was in large excess.
In Chapter 4, the copolymer poly[DMAEMA-b-(styrene-r-NHSM)] was used as a template for the synthesis of various poly(methacrylamides). Copolymer conjugation reactions were carried out using two mono-amines (4-amino-methyl pyridine and benzyl amine), and two diamines (ethylene diamine and N,N-bis(3- aminopropyl) methylamine). Complete conversions were achieved for all the amines studied. The poly(methacrylamide) copolymers formed were water soluble and possessed lower critical solution temperature (LCST) properties. Their LCST values were found to be lower than that of the macro initiator poly(DMAEMA). In the reaction with diamines, which also act as cross-linker, the block copolymer self-assembled into simple core-shell micelles where the NHSM core could be fixed via crosslinking. Water-soluble nano particles were generated, the particle size of the nano particles were measured and their size remained constant at different concentrations but varied slightly at different pH.
Polymerizations of well-defined homopolymer of N-hydroxysuccinimide methacrylate (NHSM) and copolymer poly [DMAEMA-b-(styrene-r-NHSM)] via atom transfer radical polymerization (ATRP) technique are described in Chapter 1. Well-controlled ATRP of NHSM was achieved using a combination of a Schiff base ligand N-benzyl-2-pyridylmethanimine (NBPM) and CuCl as catalyst. By using poly(DMAEMA) as macro initiator and CuBr as catalyst, poly(NHSM) obtained retained its active end group. This was demonstrated from the successful block copolymerization with NHSM and styrene, forming a water insoluble copolymer poly[DMAEMA-b-(styrene-r-NHSM)]. Poly(NHSM) and poly[DMAEMA-b-(styrene-r-NHSM)] were characterized using GPC, FT-IR and 1H NMR.
The active ester groups of poly(NHSM) react with a variety of amines to produce a range of well-defined poly(methacrylamides), some of which would have been difficult to obtain by direct polymerizations of the methacrylamide monomers. The reaction with various amines and the characterization of the poly(methacrylamides) formed are described in Chapter 2. It was found that complete conversion to poly(methacrylamide) was achieved only with unhindered primary amines, including 4-amino-methyl pyridine, 2-tetradecyl amine, 1-amino- 4-methylpiperazine and benzyl amine. On the other hand, substitution reactions with aromatic amines such as 2,3,5,6-tetrafluoro-4-(trifluoromethyl) aniline, 7- amino-4-methyl-coumarin and aniline did not occur under normal reaction conditions. All poly(methacrylamides) formed retained the same degree of polymerization (DP) and PDI.
To understand the conjugation reaction better, a detailed kinetic study of reaction between poly(NHSM) and 4-amino-methyl pyridine in solution is presented in Chapter 3. The kinetic study was conducted using FT-IR spectrophotometric method. The reactions were carried out under pseudo-first order conditions, in which the amount of amine was in large excess.
In Chapter 4, the copolymer poly[DMAEMA-b-(styrene-r-NHSM)] was used as a template for the synthesis of various poly(methacrylamides). Copolymer conjugation reactions were carried out using two mono-amines (4-amino-methyl pyridine and benzyl amine), and two diamines (ethylene diamine and N,N-bis(3- aminopropyl) methylamine). Complete conversions were achieved for all the amines studied. The poly(methacrylamide) copolymers formed were water soluble and possessed lower critical solution temperature (LCST) properties. Their LCST values were found to be lower than that of the macro initiator poly(DMAEMA). In the reaction with diamines, which also act as cross-linker, the block copolymer self-assembled into simple core-shell micelles where the NHSM core could be fixed via crosslinking. Water-soluble nano particles were generated, the particle size of the nano particles were measured and their size remained constant at different concentrations but varied slightly at different pH.
Date Issued
2008
Call Number
QD281.P6 Poc
Date Submitted
2008