Related Experiment Video
Updated: Aug 14, 2026
10:53
Anionic Polymerization of an Amphiphilic Copolymer for Preparation of Block Copolymer Micelles Stabilized by π-π Stacking Interactions
Published on: October 10, 2016
Thermotropic behavior of poly(oxyethylene) cholesterol ethers
M Arturo López-Quintela1, Akira Akahane, Carlos Rodríguez
1Departamento de Química Física, Facultad de Química, Universidad de Santiago, Santiago de Compostela, E-15782, Spain.
Journal of Colloid and Interface Science
|November 18, 2005
Summary
Poly(oxyethylene) cholesterol ether surfactants exhibit unique fusion mechanisms dependent on chain length. Short chains form liquid crystal phases, while long chains show typical solid-liquid transitions, revealing distinct thermotropic behaviors.
Area of Science:
- Materials Science
- Physical Chemistry
- Polymer Science
Background:
- Poly(oxyethylene)-type surfactants typically exhibit conventional solid-liquid transitions.
- The influence of cholesterol moieties on surfactant thermotropic behavior is not fully understood.
Purpose of the Study:
- To investigate the thermotropic behavior of poly(oxyethylene) cholesterol ether surfactants.
- To elucidate the impact of poly(oxyethylene) chain length on surfactant fusion mechanisms and phase transitions.
Main Methods:
- Differential Scanning Calorimetry (DSC) for thermal analysis.
- Small-angle X-ray Scattering (SAXS) for structural characterization.
- Analysis of chain length effects on phase behavior.
Main Results:
- Observed a novel fusion mechanism in poly(oxyethylene) cholesterol ether surfactants, deviating from conventional systems.
- Short chain lengths (n < or = 10) exhibited a transition through a birefringent liquid crystal (LC) phase, attributed to cholesterol predominance.
- Long chain lengths (n > or = 15) displayed a typical solid-liquid transition, with polymer importance increasing and leading to solid crystalline structures at low temperatures.
- Identified an antiparallel packing structure with overlapped chains in both solid and LC phases.
- Observed a zigzag chain configuration, transitioning to a meander configuration for the longest surfactant (n = 30).
Conclusions:
- The chain length of poly(oxyethylene) cholesterol ether surfactants critically dictates their thermotropic behavior and fusion mechanisms.
- The cholesterol moiety plays a significant role in inducing liquid crystal phases in short-chain surfactants.
- Surfactant chain configuration and packing structures are influenced by chain length and phase.
More Related Videos
Related Concept Videos
01:26Polymer 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...
01:17Thermal Electrocyclic Reactions: Stereochemistry
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
01:14Polymer 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...
01:20Types 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...
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...
01:26Membrane Fluidity
Membrane fluidity is explained by the fluid mosaic model of the cell membrane, which describes the plasma membrane structure as a mosaic of components—including phospholipids, cholesterol, proteins, and carbohydrates—that gives the membrane a fluid character.
Mosaic nature of the membrane
The mosaic characteristic of the membrane helps the plasma membrane remain fluid. The integral proteins and lipids exist as separate but loosely-attached molecules in the membrane. The membrane is a relatively...
Mosaic nature of the membrane
The mosaic characteristic of the membrane helps the plasma membrane remain fluid. The integral proteins and lipids exist as separate but loosely-attached molecules in the membrane. The membrane is a relatively...
01:23Membrane Fluidity
Cell membranes are composed of phospholipids, proteins, and carbohydrates loosely attached to one another through chemical interactions. Molecules are generally able to move about in the plane of the membrane, giving the membrane its flexible nature called fluidity. Two other features of the membrane contribute to membrane fluidity: the chemical structure of the phospholipids and the presence of cholesterol in the membrane.Fatty acids tails of phospholipids can be either saturated or...