Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı

The Prepararation and Characterization of Ionic Poly(N- ısopropylacrylamide) Copolymers

In this thesis, a series of crosslinked, cationic copolymer gels, poly(N-isopropylacrylamide-co-N,N-dimethylaminoethyl methacrylate) [P(NIPAM-co-DMAEMA)] and poly(N-isopropylacrylamide-co-N,N-dimethylaminoethyl methacrylate sulfate) [P(NIPAM-co-DMAEMASA)], were prepared from N-isopropylacrylamide (NIPAM) and N,N-dimethylaminoethyl methacrylate (DMAEMA)/N,N-dimethylaminoethyl methacrylate sulfate (DMAEMASA). The properties of NIPAM-DMAEMASA gel, which was prepared for the first time in this study, were compared with those of NIPAM-DMAEMA gels prepared from non-modified DMAEMA with acid. Polymerization reactions were performed by using ammonium persulphate (APS) as initiator and N,N,N’,N’-tetramethylethylenediamine (TEMED) as accelerator in distilled water at 40oC. While the amount of the crosslinker N,N’-methylene bis acrylamide (NMBA) was varied between 0.5 and 2 mol % with respect to the total monomer content, the initial total monomer concentration was kept constant at 0.8 M. The swelling behavior of the gels was investigated as a function of pH and temperature of the swelling medium. The variation of the equilibrium swelling values (ESV) of hydrogels with temperature was studied in distilled water at different temperatures (10, 20, 30 and 40oC). In order to determine the pH-dependent swelling of gels, they were immersed in buffer solutions with different pH values (2.2, 2.8, 5.0, 7.0, 8.5 and 10.0) and constant ionic strength (0.1 M) at 20oC for 24 h. Then, the ESVs were determined by gravimetric method.

NIPAM-DMAEMASA or NIPAM-DMAEMA gels were characterized by elemental analysis and Fourier Transform Infrared Spectroscopy (FTIR) methods. In addition, microscopic morphology of the copolymers was investigated by Scanning Electron Microcopy (SEM).

In this thesis study, transparent NIPAM hydrogels in appearance were prepared at 40oC that is higher than the lower critical solution temperature (LCST) of poly(N-isopropylacrylamide). The equilibrium swelling values of NIPAM-DMAEMASA copolymers decreased with the increase in the contents of DMAEMASA and NMBA, but they increased with the temperature of swelling medium. The comparison between the equilibrium swelling values of NIPAM-DMAEMASA and NIPAM-DMAEMA copolymers in distilled water at 20oC showed that the former polymers absorb 5.5 times more water than the latter. The equilibrium swelling values of NIPAM-DMAEMA copolymers decreased with the increase in DMAEMA content of polymer and the temperature of swelling medium. In addition, LCST of that copolymer was determined as 20oC. While NIPAM-DMAEMASA gels displayed a phase transition at pH=5 in buffer solutions with ionic strength of 0.1 M at 20oC, the pH of phase transition for NIPAM-DMAEMA gels shifted with DMAEMA content from 5 to 7.

Keywords: N-isopropylacrylamide, N,N-dimethylaminoethyl methacrylate, N,N-dimethylaminoethyl methacrylate sulfate, swelling, hydrogel


BAL Ayça
Danışman : Prof.Dr. Saadet K.PABUCCUOĞLU

Anabilim Dalı : Kimya Mühendisliği

Programı : Kimyasal Teknolojiler

Mezuniyet Yılı : 2009

Tez Savunma Jürisi : Prof.Dr.Saadet K.PABUCCUOĞLU

Prof.Dr.Umur DRAMUR

Prof.Dr.Gülten ATUN

Prof.Dr.Ş.İsmail KIRBAÇLILAR

Doç.Dr.Gamze GÜÇLÜ