Related Experiment Video
Updated: Aug 10, 2026
10:54
Facile and Efficient Preparation of Tri-component Fluorescent Glycopolymers via RAFT-controlled Polymerization
Published on: June 19, 2015
Negative excess interfacial entropy between free and end-grafted chemically identical polymers
1Institut de Chimie des Surfaces et Interfaces, CNRS, 15, rue Jean Starcky, B.P. 2488, 68057 Mulhouse Cedex, France.
Physical Review Letters
|January 3, 2001
Summary
We studied polymer melts and found negative interfacial entropy, unlike other liquids. This suggests polymer compressibility affects surface behavior, differing from current theories.
Area of Science:
- Polymer Science
- Physical Chemistry
- Materials Science
Background:
- Interfacial tension is crucial for understanding material properties.
- Liquid surfaces and interfaces typically exhibit positive excess interfacial entropy.
- Existing theories often neglect the compressibility of polymer melts.
Purpose of the Study:
- To measure the temperature dependence of interfacial tension in polymer melts.
- To investigate the excess interfacial entropy (Delta S(MB)) at polymer-polymer interfaces.
- To compare experimental findings with theoretical predictions.
Main Methods:
- Experimental measurement of interfacial tension.
- Analysis of temperature dependence.
- Comparison with theoretical models.
Main Results:
- The excess interfacial entropy (Delta S(MB)) was found to be extremely small and negative.
- This contrasts sharply with positive Delta S(MB) observed in liquid surfaces and interfaces.
- Significant discrepancies were found between experimental data and theoretical predictions.
Conclusions:
- Polymer melt compressibility is a key factor influencing interfacial properties.
- Current theories need refinement to incorporate finite compressibility effects.
- The study provides new insights into polymer interfacial behavior.
Related Concept Videos
02:21Chemical and Solubility Equilibria
The free energy change associated with dissolving a solute in a liter of solvent is called the free energy of a solution, ΔGsolution. The overall ΔGsolution is expressed as the balance of ΔGinteraction against the always-favorable free-energy of mixing, ΔGmixing. Solution formation is favorable if ΔGsolution is less than zero, whereas it is unfavorable if ΔGsolution is greater than zero. In short, for a solution to form and complete dissolution to take place, the Gibbs energy change must be...
02:35Free-Radical Chain Reaction and Polymerization of Alkenes
The conversion of alkenes to macromolecules called polymers is a reaction of high commercial importance. The structure of the polymer is defined by a repeating unit, while the terminal groups are considered insignificant. The average degree of polymerization represents the number of repeating units in the polymer molecule and is denoted by the subscript n.
01:21Polymer 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...
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...
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...
01:17Radical Chain-Growth Polymerization: Chain Branching
The skeletal structure of polymers synthesized via radical polymerization is always branched. For example, the polymerization of ethylene by radical polymerization results in a low-density grade of polyethylene with a heavily branched skeletal structure. Here, the radical site abstracts hydrogen from the growing chain, and the radical site shifts from the end (a primary carbon center) to anywhere within the growing chain (a secondary carbon center). Consequently, the part of the chain from the...
01:08Molecular Weight of Step-Growth Polymers
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...