Olefin polymerization and copolymerization
Fakhrossadat Mirtaleb; Mohammadreza Jozaghkar; Farshid Ziaee
Abstract
In this study, well-defined α-methyl styrene – olefin triblock copolymers were synthesized via living anionic polymerization using alkyl lithium as an initiator and 1,12-dibromododecane as a coupling agent. The polymerization was conducted in cyclohexane under an inert atmosphere at moderate ...
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In this study, well-defined α-methyl styrene – olefin triblock copolymers were synthesized via living anionic polymerization using alkyl lithium as an initiator and 1,12-dibromododecane as a coupling agent. The polymerization was conducted in cyclohexane under an inert atmosphere at moderate temperature, allowing for precise control over the molecular architecture and narrow molecular weight distribution. Gel permeation chromatography (GPC) revealed monomodal elution curves with dispersity values close to unity, confirming the living nature of the polymerization process and the high structural homogeneity of the resulting copolymers. Structural characterization was performed using 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. The 1H NMR spectra confirmed the successful formation of block copolymers through the identification of characteristic chemical shifts corresponding to the initiator, αMS blocks, and central dodecane units. Notably, the absence of brominated end-groups in the spectrum supports complete coupling and high end-group fidelity. Furthermore, 13C NMR analysis revealed well-defined chemical shifts associated with aromatic, methine, and methylene carbons. The disappearance of signals corresponding to bromine-bound methylene carbons confirmed the full consumption of the coupling agent and the effective formation of the triblock structure. These findings validate the successful synthesis of αMS-based triblock copolymers with a high degree of control over molecular parameters, establishing a robust foundation for tailoring thermomechanical and morphological properties for advanced material applications.
Olefin polymerization and copolymerization
Mohammad Reza Jozaghkar; Farshid Ziaee
Abstract
Innovative strides in polymer synthesis have led to the successful living anionic polymerization of styrene-olefin triblock copolymers, yielding varying molecular weights and a remarkably narrow dispersity (Đ) in cyclohexane solvent at 45°C, initiated by n-butyllithium. The novel approach employs ...
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Innovative strides in polymer synthesis have led to the successful living anionic polymerization of styrene-olefin triblock copolymers, yielding varying molecular weights and a remarkably narrow dispersity (Đ) in cyclohexane solvent at 45°C, initiated by n-butyllithium. The novel approach employs anionic polymerization, augmented by the aid of a coupling agent known as 1,12-dibromododecane. Unlike traditional alcohol-based methods employed in polystyrene synthesis, this coupling agent, introduced at the end of the reaction, grafts two living macro-styrene chains with the dodecane chain, effectively acting as the pivotal second component in the formation of the triblock copolymer. Extensive experimentation pinpointed 45°C as the optimal temperature for anionic copolymerization in cyclohexane solvent. The comprehensive analysis, encompassing 13C NMR, 1H NMR, FTIR spectroscopy, and GPC, confirms the successful synthesis of styrene-dodecane-styrene triblock copolymer. The NMR results illustrate successful molecular structures, while GPC attests to the precision, showing a narrow Đ of below 1.2. This pioneering approach not only underscores the efficiency of anionic polymerization in the synthesis of styrene-olefin-styrene triblock copolymer using termination strategy but also promises extensive implications in material science and industrial applications.
Seyed Mehrdad Jalilian; Mohammad Reza Jozaghkar; Farshid Ziaee
Abstract
In this particular study, shear stability, pour point temperature and cold cranking simulation viscosity of different poly (alkyl methacrylate) homopolymers were investigated. The successful synthesis of the homopolymers was verified using FTIR and 1H NMR spectroscopy. From the experimental results, ...
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In this particular study, shear stability, pour point temperature and cold cranking simulation viscosity of different poly (alkyl methacrylate) homopolymers were investigated. The successful synthesis of the homopolymers was verified using FTIR and 1H NMR spectroscopy. From the experimental results, it was perceived that shear stability and low-temperature performance of the modified oil are strongly dependent on alkyl length and synthesis reaction conditions. Higher shear stability was observed for the samples possessing shorter alkyl chain lengths. An increase in initiator concentration and reaction temperature led to a decrease in molecular weight and an increase in shear stability. Moreover, poly(alkyl methacrylate) homopolymers containing longer alkyl chain lengths represented better influence in the reduction of the size and cohesiveness of the crystal structure of paraffin wax. The results also revealed that the synthesized homopolymers with lower molecular weight play a greater performance in controlling friction at low temperatures.
Olefin polymerization and copolymerization
Mohammad Reza Jozaghkar; Seyed Mehrdad Jalilian; Farshid Ziaee
Abstract
This study was designed to investigate the effect of molar ratio of 1-octene and type as well as concentration of Lewis acids on the free radical copolymerization of butyl methacrylate (BMA) with 1-octene. The synthesized copolymers have been substantially described by FTIR, 1H NMR, GPC and DSC. The ...
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This study was designed to investigate the effect of molar ratio of 1-octene and type as well as concentration of Lewis acids on the free radical copolymerization of butyl methacrylate (BMA) with 1-octene. The synthesized copolymers have been substantially described by FTIR, 1H NMR, GPC and DSC. The quantitative 1H NMR and GPC demonstrated that by increase in the molar ratio of 1-octene and Lewis acids to BMA, the incorporation of 1-octene in the copolymer backbone enhanced, Mn reduced and polydispersity became narrower. The maximum incorporation of 1-octene (13.7%) was observed for sample CSC7 having [1-octene/BMA] of 3 mol% and [AlCl3/BMA] of 1.5 mol%. The DSC results confirmed the NMR and GPC outcomes, suggesting a decrease in Tg by increasing 1-octene in the copolymer backbone. Moreover, it is found that temperature has a remarkable influence on the copolymerization behavior. The results also showed that by substituting the acrylate monomer from butyl methacrylate to butyl acrylate, the incorporation of 1-octene increased.
