Emergence and Stability of Helical Superstructures in ABC Triblock Copolymers
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Abstract:
The emergence and stability of superstructured cylindrical phases in frustrated ABC linear triblock copolymers are investigated by the self-consistent field theory. Our results reveal that the complex single/double/triple helices-on-cylinder phases are formed when the straight cylinders-on-cylinder and rings-on-cylinder phases are frustrated due to packing constraints. A free energy comparison indicates that the double and triple helical phases are stable, whereas the other cylinders-on-cylinder phases are metastable. In addition, the chirality and rotation for the helical supercylinders are considered in our calculations. Our theoretical prediction is consistent with a number of experimental observations.Keywords:
Metastability
Chirality
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Abstract The compositions of copolymers formed by reacting styrene or α‐methylstyrene (M) with lithium in tetrahydrofuran in the presence of varying amounts of alkyl dibromides (RX 2 ) have been studied. Regular copolymers of structure are formed at 2:1 monomer to dibromide molar stoichiometry, but they become less regular and richer in monomer as the proportion of dihalide decreases. α‐Methylstyrene copolymers change systematically with reactant ratios and a series of materials can be prepared with different glass transition temperatures which can be related to the copolymer compositions. The fast rate of anionic homopropagation of styrene after consumption of the dihalide prevented pure copolymer from being prepared free of homopolystyrene. However, it is shown that the composition of the styrene copolymers is much more sensitive to the initial reactant ratios than is that of the α‐methylstyrene copolymers.
Stoichiometry
Tetrahydrofuran
Molar ratio
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N-vinylformamid is isomer of acrylamide.The latter can be used to replace copolymerization of N-vinylformamid and its copolymer,reducing second environmental pollution.In different molar ratio's condition,N-vinylformamid and acrylamide can carry out copolymerization before the copolymerization of N-vinylcaprolactam and N-vinylformamid continue.A study of the different monomers and different molar ratio's process of copolymerization is conducted.The copolymer compositions are analyzed and the glass transition temperatures of copolymer are determined.
Molar ratio
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Combining the copolymerization principle,the compatibilization of synthesized copolymer from SBS graft MMA to PS/PVC copolymer was determined.The mechanics performance of the grafting copolymer was amalysed.The graft copolymer or block copolymer was used as the 3rd component,Addition of the 3rd component to the dual incompatible copolymer is a effective method to control the phase state structure and improve mechanics performance.
Compatibilization
Component (thermodynamics)
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Acrylic acid
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反应比率是确定的一个传统的参数在 copolymerization 的反应动力学，它为潜在地控制聚合物的微观结构并且指导 copolymerization 进程是重要的。我们用 tube-NMR 技术的最近的实验启用我们到在 situ 监视器，集中在 anionic copolymerization 过程期间合作单体介绍。这激发我们重游 Mayo 吊楔(ML ) 方程，它是反应比率的推导的基础并且广泛地另外被利用了 copolymerization。我们发现尽管一个明确的 ML 表达式是合乎需要的便于有试验性的数据的计算和关联，它在我们的 anionic copolymerization 实验以及在文学可得到的一些数据失败。起源被归功于到在 ML 方程必要的稳定的州的假设的有效性。这个假设能在 anionic copolymerization 被释放并且由生活的链结束的全面集中在整个 copolymerization 使经常的事实代替了。其他的数字方法被利用了获得率常数并且因而反应比率。我们的工作建议 ML 方程应该小心地被使用。
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The properties of copolymerization of D F 3, D 4 were studied . It is a balancing copolymerization with opening cycloes. The produce rate of copolymer and high copolymer is almost constant when it is balanced. As for the discovery of alkaline catalyst, strong catalyst is good for producing copolymer of high molecular weight. Owing to the rise of temperature, the copolymerization speeds up, molecular weight of the copolymer decreases down, and it forms a relationship of ln ~1/ T . At the beginning of copolymerizing, to rise the temperature, and then, to reduce it. The purpose of shortening the time of copolymerization and increasing the molecular weight of copolymer can be got.
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We demonstrate that long random copolymers (monomer fraction $f=0.48$) can be more effective than a long symmetric block copolymer in strengthening interfaces between immiscible homopolymers. The effectiveness of the random copolymer is inferred to result from each random copolymer crossing the interface multiple times, entangling with the homopolymer on either side of the interface; as $f$ is increased from 0.48 to 0.77, the effectiveness decreases markedly as the copolymer becomes less entangled with the homopolymer (corresponding to the minor component in the copolymer) on one side of the interface.
Random phase approximation
Interface (matter)
Component (thermodynamics)
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