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A study on the copolymerization of n-acryloyl-n'-methyl piperazine and 2-hydroxyethyl methacrylate
Author
Teng, Swee Hoon
Supervisor
Gan, Leong Huat
Abstract
Hydrophilic homopolymer of 2-hydroxyethyl methacrylate (HEMA) and copolymer of N-acryloyl-N'-methyl piperazine (AcrNMP) with HEMA were synthesized by free radical polymerization in dioxane solution at 75oC, using 2,2'-azobisisobutyronitrile (AIBN) as initiator.
Copolymer compositions were obtained using IR and elemental analysis. The reactivity ratios of the copolymerization were obtained by the application of linearization methods of Finemann-Ross (F-R) and Kelen-Tudos (K-T). The results derived from IR analysis clearly showed that the copolymerization yielded an alternating structure with reactivity ratios, r1= 0.263 + 0.01 1, r2 = 0.615 ± 0.097 as obtained by the F-R method and r1 = 0.227 + 0.074, r2 = 0.529 ± 0.145 by the K-T method. Microstructural data calculated statistically by the methods of Igarashi and by the mean sequence equations supported the findings that the copolymer was alternating. The reactivity ratios determined from the elemental analysis also indicated an alternating copolymerization system with r1 = 0.279 ± 0.019, r2 = 0.846 ± 0.185 (F-R) and r1l = 0.261 ± 0.109, r2 = 0.778 ± 0.242 (K-T).
Glass-transition temperatures (Tg) of the copolymers were determined by Werential scanning calorimetry (DSC). However, the results did not demonstrate any meaningful trend. This was attributed to the presence of water in the sample because of the hydrophilic nature of the copolymer. The presence of water in the copolymer will impart a plasticizing effect and this affects the value of Tg.
Crosslinked copolymers were prepared by bulk polymerization of AcrNMP and HEMA, with crosslinker ethylene glycol dimethacrylate (EGDMA) and initiator, AIBN, at 70oC. The crosslinked copolymers were hydrogels. These hydrogels were characterized by the equilibrium swelling measurements at 25 'C. The equilibrium water contents, swelling coefficients and soluble fraction were calculated.
Copolymer compositions were obtained using IR and elemental analysis. The reactivity ratios of the copolymerization were obtained by the application of linearization methods of Finemann-Ross (F-R) and Kelen-Tudos (K-T). The results derived from IR analysis clearly showed that the copolymerization yielded an alternating structure with reactivity ratios, r1= 0.263 + 0.01 1, r2 = 0.615 ± 0.097 as obtained by the F-R method and r1 = 0.227 + 0.074, r2 = 0.529 ± 0.145 by the K-T method. Microstructural data calculated statistically by the methods of Igarashi and by the mean sequence equations supported the findings that the copolymer was alternating. The reactivity ratios determined from the elemental analysis also indicated an alternating copolymerization system with r1 = 0.279 ± 0.019, r2 = 0.846 ± 0.185 (F-R) and r1l = 0.261 ± 0.109, r2 = 0.778 ± 0.242 (K-T).
Glass-transition temperatures (Tg) of the copolymers were determined by Werential scanning calorimetry (DSC). However, the results did not demonstrate any meaningful trend. This was attributed to the presence of water in the sample because of the hydrophilic nature of the copolymer. The presence of water in the copolymer will impart a plasticizing effect and this affects the value of Tg.
Crosslinked copolymers were prepared by bulk polymerization of AcrNMP and HEMA, with crosslinker ethylene glycol dimethacrylate (EGDMA) and initiator, AIBN, at 70oC. The crosslinked copolymers were hydrogels. These hydrogels were characterized by the equilibrium swelling measurements at 25 'C. The equilibrium water contents, swelling coefficients and soluble fraction were calculated.
Date Issued
1997
Call Number
QD381 Ten
Date Submitted
1997