统计共聚合物薄膜中的顺序顺序过渡由LCST类型的行为诱导
Mao Kikuchi1, Mitsuo Hara2, Shusaku Nagano3
1Graduate School of Science and Engineering, Yamagata University, 1-4-12 Kojirakawa-Machi, Yamagata 990-8560, Japan.
The journal of physical chemistry. B
|July 24, 2024
概括
共聚合物薄膜通过水合和脱水来改变它们的有序结构. 这项研究揭示了多 ((N-octadecyl acrylamide-stat-hydroxymethyl acrylamide) 薄膜如何在分离和混合的薄膜结构之间切换,从而影响胀特性.
科学领域:
- 聚合物科学 聚合物科学
- 材料科学 材料科学 材料科学
- 物理化学 物理化学
背景情况:
- 共聚合物薄膜为高级应用提供可调节的性能.
- 了解聚合物中的结构性质关系对于材料设计至关重要.
- 和脱水过程可以诱导聚合物的显著结构变化.
研究的目的:
- 为了研究特定的共聚合物薄膜中有序结构的形成.
- 探索水合和脱水对共聚合物的状结构的影响.
- 为了将结构过渡与片的膨胀行为相关联.
主要方法:
- 通过自由基共聚合合成的多 (N-octadecyl acrylamide-stat-hydroxymethyl acrylamide) 的合成.
- 在受控的湿度和温度下制备和回火共聚合物薄膜.
- 使用石英晶体微平衡 (QCM) 进行结构转变的表征和胀特性分析.
主要成果:
- 一种统计共聚物p ((ODA50/HEAm50) 被合成,共聚物比例为1:1.
- 在60°C的加水过程中,诱导了一种侧链分离的状结构 (SCSegL).
- 在90°C的脱水过程中,薄膜转化为侧链混合层状 (SCMixL) 结构.
- 同聚合物在50°C左右表现出类似于较低临界溶液温度 (LCST) 的行为.
- 结构过渡显著影响了片的膨胀特性.
结论:
- ODA50/HEAm50共聚合物薄膜经历了一种由水化-脱水驱动的顺序到顺序过渡.
- 由于水友和疏水性单元之间的分离,形成了SCSegL结构.
- 在脱水后形成SCMixL结构,减少应变并改变胀.
- 这项研究表明,可通过环境刺激对共聚合物薄膜进行可调节的结构控制.
相关概念视频
Cationic Chain-Growth Polymerization: Mechanism
2.3K
The cationic polymerization mechanism consists of three steps: initiation, propagation, and termination. In the initiation step of the polymerization process, the π bond of a monomer gets protonated by the Lewis acid catalyst, which is formed from boron trifluoride and water. The protonation of the π bond generates a carbocation stabilized by the electron‐donating group. In the propagation step, the π bond of the second monomer acts as a nucleophile and attacks the...
2.3K
Step-Growth Polymerization: Overview
3.4K
Step-growth or condensation polymerization is a stepwise reaction of bi or multifunctional monomers to form long-chain polymers. As all the monomers are reactive, most of the monomers are consumed at the early stages of the reaction to form small chains of reactive oligomers, which then combine to form long polymer chains in the late stages. Hence, the reaction has to proceed for a long time to achieve high molecular weight polymers.
Many natural and synthetic polymers are produced by...
Many natural and synthetic polymers are produced by...
3.4K
Ziegler–Natta Chain-Growth Polymerization: Overview
3.2K
Ziegler–Natta polymerization is another form of addition or chain‐growth polymerization used for synthesizing linear polymers over branched polymers. The catalyst used for polymerization is the Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, who developed it in 1953. This catalyst is an organometallic complex of titanium tetrachloride and triethyl aluminum, with the active form of the catalyst being an alkyl titanium compound. Using the Ziegler–Natta...
3.2K
Molecular Weight of Step-Growth Polymers
2.2K
Step growth polymerization involves bi or multifunctional monomers. Bifunctional monomers react to form linear step growth polymers, whereas multifunctional monomers react to form non-linear or branched polymers.
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...
2.2K
Polymer Classification: Stereospecificity
2.4K
Polymerization generates chiral centers along the entire backbone of a polymer chain. Accordingly, the stereochemistry of the substituent group has a significant effect on polymer properties. Polymers formed from monosubstituted alkene monomers feature chiral carbons at every alternate position in the polymer backbone. Relative to the predominant orientation of substituents at the adjacent chiral carbons, the polymer can exist in three different configurations: isotactic, syndiotactic, and...
2.4K
Polymer Classification: Crystallinity
2.8K
Unlike ionic or small covalent molecules, polymers do not form crystalline solids due to the diffusion limitations of their long-chain structures. However, polymers contain microscopic crystalline domains separated by amorphous domains.
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
2.8K


