Related Experiment Video
Updated: Jun 16, 2026
06:55
Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level
Published on: September 26, 2016
Optical and electrical effects during polymerization and depolymerization in liquid sulfur: indications for the
Applied Optics
|February 19, 2010
Summary
Liquid sulfur undergoes polymerization and depolymerization, altering its optical and electrical properties. These structural changes suggest liquid sulfur
Area of Science:
- Materials Science
- Physical Chemistry
- Condensed Matter Physics
Background:
- Liquid sulfur exhibits complex structural transitions.
- Polymerization and depolymerization are key processes influenced by thermodynamic conditions.
Purpose of the Study:
- To investigate the optical and electrical consequences of structural transitions in liquid sulfur.
- To understand the relationship between liquid sulfur structure and its physical properties.
Main Methods:
- Observation of color changes during thermal transitions.
- Measurement of light scattering and transmission using He-Ne laser.
- Electrical conductivity measurements under pulsed laser irradiation.
- Analysis of temperature coefficient of resistance.
- Characterization of current-voltage (I-V) behavior.
Main Results:
- Observed color changes from yellow to red correlating with structural changes.
- Detected peaks in light scattering and minimum transmission at transition temperatures.
- Noted a decrease in laser-induced current above the polymerization temperature (T(p)).
- Identified two sign changes in the temperature coefficient of resistance near T(p) and depolymerization temperature (T(d)).
- Characterized superlinear I-V characteristics above T(d).
Conclusions:
- Structural transitions in liquid sulfur significantly impact its optical and electrical properties.
- The observed phenomena support a nonuniformity model over a random network model for liquid sulfur structure.
- Thermodynamic conditions critically influence the macroscopic behavior of liquid sulfur.
More Related Videos
Related Concept Videos
01:10Polymers: Molecular Weight Distribution
For any given polymer, the weight average molecular weight (Mw) is higher than, if not equal to, the number average molecular weight (Mn). The only situation in which the weight average molecular weight and the number average molecular weight are equal is when a polymer consists only of chains with equal molecular weight. However, this never happens in a synthetic polymer, since it is difficult to control the polymerization process up to a molecular level with accuracy to a hundred percent.
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...
01:21Polymer 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...
01:03Step-Growth Polymerization: Overview
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...
01:24Determination of Molar Masses of Polymers I
Polymerization produces macromolecules with a range of chain lengths due to the random nature of molecular growth processes. As chains form and terminate at different stages, a single polymer sample contains molecules of varying sizes rather than a uniform structure. This variability is described using average molar masses and distribution-related parameters, which together provide a comprehensive understanding of polymer characteristics.The distribution of molar masses plays a critical role in...
00:57Cationic Chain-Growth Polymerization: Mechanism
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 generated carbocation,...