建立马克-霍温克-萨库拉达在多种溶剂系统中素方程及其对溶液构成的影响
Wei Ning Goh1, Rou Li1, Shang-Ta Wang2
1Department of Food Science, National Taiwan Ocean University, Keelung 202301, Taiwan.
Polymers
|February 27, 2026
概括
新的Mark-Houwink-Sakurada (MHS) 基方程是使用各种溶剂和温度开发出来的. 这些方程可以准确地确定分子重量,并提供对基的洞察力.
科学领域:
- 聚合物科学 聚合物科学
- 材料化学 材料化学
- 生物聚合物特性表征
背景情况:
- 马克-霍温克-萨库拉达 (MHS) 方程对于从内在粘度来估计聚合物分子重量至关重要.
- 现有的基MHS方程受到狭窄的溶剂适用性限制.
- 精确的分子量测定对于了解素的特性和应用至关重要.
研究的目的:
- 为基建立新的MHS方程,适用于各种溶剂系统和温度.
- 为了促进可靠的基分子量确定.
- 为了研究在不同的化学环境中素的溶液构成.
主要方法:
- 用H2O2降解制备了具有不同分子重量的素样本.
- 重量平均分子量 (Mw) 通过高性能尺寸排除色谱 (HPSEC) 来确定.
- 内在粘度 ([η]) 用毛细管粘度测量在25和30°C的LiCl/DMAc,NaOH/尿素和NaOH/酸溶剂中进行测量.
- MHS方程是从Mw与[η]的双对数图谱中得出的.
主要成果:
- 固有粘度顺序是LiCl/DMAc > NaOH/尿素 > NaOH/酸在恒定的MW和温度下.
- 温度升高导致了更高的内在粘度和形状参数 (a).
- 基在LiCl/DMAc和NaOH/尿素中表现出类似杆状的形状 (a = 0.79-0.97),在NaOH/酸中表现出随机的线圈行为 (a = 0.56-0.69).
结论:
- 新建立的MHS方程显著扩大了用于基分子量分析的溶剂适用性.
- 这项研究提供了对素溶液构成有价值的见解,其构成受溶剂和温度的影响.
- 这些发现支持对基基材料进行更准确的表征和应用开发.
更多相关视频
09:43Interfacial Molecular-level Structures of Polymers and Biomacromolecules Revealed via Sum Frequency Generation Vibrational Spectroscopy
Published on: August 13, 2019
9.9K
08:59A Freeze-Thawing Method to Prepare Chitosan-Polyvinyl alcohol Hydrogels Without Crosslinking Agents and Diflunisal Release Studies
Published on: January 14, 2020
19.3K
相关概念视频
02:25Molecules with Multiple Chiral Centers
15.5K
Molecules that possess multiple chiral centers can afford a large number of stereoisomers. For instance, while some molecules like 2-butanol have one chiral center, defined as a tetrahedral carbon atom with four different substituents attached, several molecules like butane-2,3-diol have multiple chiral centers. A simple formula to predict the number of stereoisomers possible for a molecule with n chiral centers is 2n. However, there can be a lower number where some of the stereoisomers are...
15.5K
01:17Chemical Shift: Internal References and Solvent Effects
1.5K
In an NMR sample, precise measurement of the absolute absorption frequencies of nuclei is difficult. A standard internal reference compound is added, and the frequency difference between the reference signal and sample signals is measured.
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...
1.5K
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
1.3K
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
1.3K
02:11Conformations of Cyclohexane
16.5K
Cyclohexane does not exist in a planar form due to the high angle and torsional strain it would experience in the planar structure. Instead, it adopts non-planar chair and boat conformations.
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal...
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal...
16.5K
02:34Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
9.8K
The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.
9.8K
02:30Stability of Substituted Cyclohexanes
16.4K
This lesson discusses the stability of substituted cyclohexanes with a focus on energies of various conformers and the effect of 1,3-diaxial interactions.
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
16.4K