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相关概念视频

Types of Step-Growth Polymers: Polyesters01:20

Types of Step-Growth Polymers: Polyesters

The introduction of polyesters has brought major development to the textile industry. The wrinkle-free behavior of polyester blends has eliminated the need for starching and ironing clothes.
Polyesters are commonly prepared from terephthalic acid and ethylene glycol; the crude product is known as poly(ethylene terephthalate) or PET. However, polyesters are synthesized industrially by transesterification of dimethyl terephthalate with ethylene glycol at 150 °C. The two reactants and the polymer...
Polymer Classification: Architecture01:14

Polymer Classification: Architecture

Polymers are classified as linear or branched on the basis of their chain architecture. The polymer chains in linear polymers have a long chain-like structure with minimal to no branching at all. Even if a polymer features large substituent groups on the monomer, which appear as branches to the skeleton, it is not considered a branched polymer. A branched polymer contains secondary polymer chains that arise from the main polymer chain. The branching occurs when the polymer growth shifts from...
Characteristics and Nomenclature of Homopolymers01:00

Characteristics and Nomenclature of Homopolymers

Polymers that are made up of identical monomer units are called homopolymers. Only one repeating unit is involved in the construction of the homopolymer structure. For example, as depicted in Figure 1, polypropylene is a homopolymer constituted of propylene monomers. Here, the only repeating unit in the polymer chain is propylene.
Polymer Classification: Stereospecificity01:26

Polymer Classification: Stereospecificity

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...
Polymer Classification: Crystallinity01:21

Polymer Classification: Crystallinity

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...
Phosphodiester Linkages01:01

Phosphodiester Linkages

Overview
Phosphodiester bond forms when a phosphoric acid molecule (H3PO4) links with two hydroxyl groups (–OH) of two other molecules, forming two ester bonds. Two water molecules are released in this process. The phosphodiester bond is commonly found in nucleic acids (DNA and RNA) and plays a critical role in their structure and function.
Phosphodiester Bonds Link Nucleotides Together
DNA and RNA are polynucleotides or long chains of nucleotides that are linked together. A nucleotide is...

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相关实验视频

Updated: Jul 12, 2026

Designed for Molecular Recycling: A Lignin-Derived Semi-aromatic Biobased Polymer
10:22

Designed for Molecular Recycling: A Lignin-Derived Semi-aromatic Biobased Polymer

Published on: November 30, 2020

"多元水"的结构

J Donohue

    Science (New York, N.Y.)
    |November 21, 1969
    PubMed
    概括
    此摘要是机器生成的。

    提出了聚水的新结构,其中包含联的水分子集群,构成形十二面体. 与以前的多水结构相比,这种模型具有较少的缺点.

    科学领域:

    • 化学 化学 化学
    • 材料科学 材料科学 材料科学
    • 物理 物理学 物理

    背景情况:

    • 聚水是一种有争议的水形式,由于其不寻常的特性,一直是科学辩论的主题.
    • 之前的聚水结构模型面临着重大挑战和批评.

    研究的目的:

    • 为聚水提出一种新的结构模型.
    • 呈现一个结构与现有模型相比改进的特征.

    主要方法:

    • 水分子集群的理论建模.
    • 联网的几何分析.
    • 基于化学原理的结构特征的评估.

    主要成果:

    • 一个针对多水的拟议结构涉及水分子的结集群.
    • 这些集群排列在米十二面体的顶点上.
    • 拟议的结构比以前的模型具有较少的不利特征.

    结论:

    • 基于形十二面体的集群模型为多水提供了一个潜在的更可行的结构.
    • 这个模型解决了早期多水假设的一些局限性.

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    Last Updated: Jul 12, 2026

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    10:22

    Designed for Molecular Recycling: A Lignin-Derived Semi-aromatic Biobased Polymer

    Published on: November 30, 2020

    Modulating Shape of Polyester Based Polymersomes using Osmotic Pressure
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    Modulating Shape of Polyester Based Polymersomes using Osmotic Pressure

    Published on: April 21, 2021

    Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
    09:22

    Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives

    Published on: February 7, 2017