Biswas, Chandra Sekhar | Hazer, Baki

Article | 2015 | COLLOID AND POLYMER SCIENCE293 ( 1 ) , pp.143 - 152

Macroporous poly(N-ethylacrylamide) (PNEAM) hydrogels have been prepared in a methanol-water (1:1, v/v) mixture in the presence of 0, 0.05, 0.1, 0.15, and 0.2 M yttrium trifluoromethanesulfonate [Y(OTf)(3)] Lewis acid (LA) concentrations. SEM micrographs show that the resulted hydrogels are highly porous. Swelling ratios of all the hydrogels in water decrease with the increase in the temperature, and the hydrogels show lower critical solution temperature (LCST) volume phase transition at around 75 A degrees C. LCST of PNEAM homopolymers gradually increases with the increase in the isotacticity of the polymers. Moreover, the hydrogel . . .s show cononsolvency in different methanol-water mixtures at 50 A degrees C. Deswelling rate of the hydrogels prepared in the presence of LA is higher than the gel prepared in the absence of LA and this rate increases with increase in the LA concentration. The reswelling rate of the hydrogels also follows the same order, that is reswelling rate also increases with the increase in the LA loading in the gels. All these results are explained on the basis of the formation of the highly porous hydrogels with a higher isotactic PNEAM chain segment in a methanol-water mixture in the presence of LA Daha fazlası Daha az

Allı, Abdulkadir | Allı, Sema | Becer, C. Remzi | Hazer, Baki

Article | 2014 | JOURNAL OF THE AMERICAN OIL CHEMISTS SOCIETY91 ( 5 ) , pp.849 - 858

One-pot synthesis of graft copolymers by ring-opening polymerization and free radical polymerization using polymeric linoleic acid peroxide (PLina) is reported. Graft copolymers having structures of poly(linoleic acid)-g-polystyrene-g-poly(epsilon-caprolactone) were synthesized from PLina, possessing peroxide groups on the main chain by the combination of free radical polymerization of styrene and ring-opening polymerization of epsilon-caprolactone in one-step. Principal parameters, such as monomer concentration, initiator concentration, and polymerization time, which effect the one-pot polymerization reactions were evaluated. The o . . .btained graft copolymers were characterized by H-1-NMR and DOSY-NMR spectroscopy, gel permeation chromatography, thermal gravimetric analysis and differential scanning calorimetry techniques Daha fazlası Daha az

Kul, Dilek | Volga, Cüneyt | Yılmaz-Savaşkan, Sevil | Hazer, Baki

Article | 2002 | POLYMER BULLETIN49 ( 1 ) , pp.25 - 32

WOS: 000178013300004

Zounr, Rizwan Ali | Tüzen, Mustafa | Hazer, Baki | Khuhawar, Muhammad Yar

Article | 2018 | FOOD ANALYTICAL METHODS11 ( 9 ) , pp.2538 - 2546

A new solid-phase microextraction (SP mu E) procedure has been developed for separation and preconcentration of Sn ions by using graphite furnace atomic absorption spectrometry (GFAAS). This technique is based on the complexation of Sn(IV) ions with 1-(2-pyridylazo)-2-naphthol (PAN). The poly (epsilon-caprolactone-b-4-vinyl benzyl-g-dimethyl amino ethyl methacrylate) polymer (PCL vacr) was used as an adsorbent, and it was loaded in micropipette tip of syringe system. Sn(IV) ions were adsorbed on polymer at pH 6. Different experimental conditions were optimized such as pH, amount of complexing agent, and amount of adsorbent. The dete . . .ction limit (LOD), limit of quantification, preconcentration factor (PF), and relative standard deviation (RSD) were found as 4.5 ng L-1, 13.5 ng L-1, 100, and 3.3%, respectively. Certified reference materials were used to confirm the accuracy of the investigated procedure, and the procedure was successfully practiced for determination of entire concentration of tin within beverages and different food samples Daha fazlası Daha az

Şanal, Timur | Oruç, Olgu | Öztürk, Temel | Hazer, Baki

Article | 2015 | JOURNAL OF POLYMER RESEARCH22 ( 2 ) , pp.2538 - 2546

A novel pH-and thermo-responsive poly (epsilon-caprolactone-b-4-vinyl benzyl-g-2-(dimethyl amino ethyl) methacrylate), poly (CL-b-VB-g-DMAEMA), brush type copolymer has been described. In this study, a reversible addition-fragmentation chain transfer (RAFT) agent, 1,2-propanediol- 3-ethyl xanthogenate, was obtained through the reaction of 3-chloro-1,2-propanediol with potassium salt of ethyl xanthogenate. Poly (CL-b-VB) block copolymer was synthesized in one-pot polymerization of e-caprolactone (CL) and 4-vinyl benzyl chloride (VB) using a new dual macro-RAFT agent. In the second step of the work, chloride side groups of poly-VB in . . .poly (CL-b-VB) block copolymer were reacted with potassium salt of ethyl xanthogenate to obtain another novel macro-RAFT agent, poly (CL-b-VB)-g-xanthate (PCL-PVB-Xa). Controlled free radical living polymerization of 2-(dimethylaminoethyl) methacrylate (DMAEMA) was initiated with this PCL-VB-Xa macro-RAFT agent to obtain new poly (CL-b-VB-g-DMAEMA) comb type pH-and thermo-responsive heterograft copolymer. The homopolymer was soluble in water at pH=10-11 and not soluble at pH=12.5. A pH-sensitive feature of the brush type graft copolymer was observed between pH9.4 and 11.5 in view of their swelling/solution properties depending on the acrylic polymer inclusion. The LCST values of the multiblock brush type copolymers were found to be as low as 42.8 degrees C, while that of PDMAEMA homopolymer was 46.6 degrees C. The characterization of the products was achieved using gel-permeation chromatography (GPC), thermal, and spectrometric analysis techniques. pH- and thermo-responsiveness of the copolymers were verified by surface tension and zeta potential measurements Daha fazlası Daha az

Şanal, Timur | Koçak, İzzet | Hazer, Baki

Article | 2017 | POLYMER BULLETIN74 ( 4 ) , pp.977 - 995

This work refers to the synthesis of a series of novel chlorinated poly(E >-caprolactone) (PCL) for further functionalization of PCL. For this aim, chlorine gas was passed through into the chloroform solution to obtain chlorinated polycaprolactone. The chlorine contents in chlorinated PCL were between 0.9 and 1.6 mol%. The molecular weights of the polymers (M (n)) changed from 4853 to 9497 g/mol. As the amount of passing chlorine gas increases, the molecular weight of the chlorinated PCL was found to decrease. Pendant chloride groups of PCL were reacted with sodium azide to prepare PCL with pendant azide groups (PCL-N-3). Poly-(ethy . . .lene glycol) methyl ether (mPEG) was reacted with propargyl chloride to achieve alkynyl mPEG (mPEG-alkyn). Click reaction was then carried out by the reaction between PCL-N-3 and mPEG-alkyn to obtain PCL-g-PEG comb-type amphiphilic graft copolymer. Interestingly, SEM images of the PCL-g-PEG comb-type amphiphilic graft copolymers showed the highly microporous structure. The resulting products were characterized by H-1 NMR, FT-IR, gel-permeation chromatography, SEM, surface tension, contact angle and water uptake measurements, differential scanning calorimeter and thermogravimetric analyses techniques Daha fazlası Daha az

Hazer, Baki | Ayyıldız, Elif | Bahadır, Faruk

Article | 2017 | JOURNAL OF THE AMERICAN OIL CHEMISTS SOCIETY94 ( 9 ) , pp.1141 - 1151

This work refers to the synthesis of a new double hydrophilic thermo-responsive polymer using fatty acid macroperoxide initiator, N-isopropyl acryl amide (NIPAM) and polyethylene glycol with two primary amine ends (PEGNH2). For this purpose, oleic acid was spread out onto a petri dish and exposed to air oxygen at room temperature for 2 months. The obtained fatty acid macro-peroxide initiator was used in the free radical polymerization of NIPAM in the presence of PEGNH2. Poly oleic acid-g-PNIPAM-g-PEG graft copolymers were successfully obtained. Lower critical solution temperature (LCST) of the graft copolymer was determined by using . . . UV-Vis spectrometry with a sensible heating unit. Morphology of the fractured surface of the double hydrophilic polymers was visualized by using SEM micrographs. Graft copolymers with LCST close to body temperature were obtained by changing PEG inclusion. Structural characterization, thermal analysis and size exclusion chromatography measurements of the obtained products were done Daha fazlası Daha az