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Synthesis and characterization of diblock, triblock, and multiblock copolymers containing Poly(3-hydroxy butyrate) units

Arslan, Hülya | Menteş, Ayfer | Hazer, Baki

Article | 2004 | Journal of Applied Polymer Science94 ( 4 ) , pp.1789 - 1796

A poly[(R,S)-3-hydroxybutyrate] macroinitiator (PHB-MI) was obtained through the condensation reaction of poly[(R,S)-3-hydroxybutyrate] (PHB) oligomers containing dihydroxyl end functionalities with 4,4'-azobis(4-cyanopentanoyl chloride). The PHB-MI obtained in this way had hydroxyl groups at two end of the polymer chain and an internal azo group. The synthesis of ABA-type PHB-b-PMMA block copolymers [where A is poly(methyl methacrylate) (PMMA) and B is PHB] via PHB-MI was accomplished in two steps. First, multiblock active copolymers with azo groups (PMMA-PHB-MI) were prepared through the redox free-radical polymerization of methyl . . . methacrylate (MMA) with a PHB-MI/Ce(IV) redox system in aqueous nitric acid at 40°C. Second, PMMA-PHB-MI was used in the thermal polymerization of MMA at 60°C to obtain PHB-b-PMMA. When styrene (S) was used instead of MMA in the second step, ABCBA-type PMMA-b-PHB-b-PS multiblock copolymers [where C is polystyrene (PS)] were obtained. In addition, the direct thermal polymerization of the monomers (MMA or S) via PHB-MI provided AB-type diblocks copolymers with MMA and BCB-type triblock copolymers with S. The macroinitiators and block copolymers were characterized with ultraviolet-visible spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography, cryoscopic measurements, and thermogravimetric analysis. The increases in the intrinsic viscosity and fractional precipitation confirmed that a block copolymer had been obtained. © 2004 Wiley Periodicals, Inc Daha fazlası Daha az

Synthesis and characterization of polymeric linseed oil grafted methyl methacrylate or styrene

Çakmaklı, Birten | Hazer, Baki | Tekin, İshak Özel | Kızgut, Sait | Köksal, Murat | Menceloğlu, Yusuf

Article | 2004 | Macromolecular Bioscience4 ( 7 ) , pp.649 - 655

Syntheses of wholly natural polymeric linseed oil (PLO) containing peroxide groups have been reported. Peroxidation, epoxidation and/or perepoxidation reactions of linseed oil, either under air or under oxygen flow at room temperature, resulted in polymeric peroxides, PLO-air and PLO-ofl, containing 1.3 and 3.5 wt.-% of peroxide, with molecular weights of 2 100 and 3 780 Da, respectively. PLO-air contained cross-linked film up to 46.1 wt.-% after a reaction time of 60 d, associated with a waxy, soluble part (PLO-air-s) that was isolated with chloroform extraction. PLO-ofl was obtained as a waxy, viscous liquid without any cross-link . . .ed part at the end of 24 d under visible irradiation and oxygen flow. Polymeric peroxides, PLO-air-s and PLO-ofl initiated the free radical polymerization of both methyl methacrylate (MMA) and styrene (S) to give PMMA-graft-PLO and PS-graft-PLO graft copolymers in high yields with Mw varying from 37 to 470 kDa. The polymers obtained were characterized by FT-IR, 1H NMR, TGA, DSC and GPC techniques. Cross-linked polymers were also studied by means of swelling measurements. PMMA-graft-PLO graft copolymer film samples were also used in cell-culture studies. Fibroblast cells were well adhered and proliferated on the copolymer film surfaces, which is important in tissue engineering Daha fazlası Daha az

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