Related Experiment Video
Updated: Jul 31, 2026
10:56
Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures
Published on: May 20, 2014
Kramers problem for a polymer in a double well
1Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India.
Summary
This study investigates how long polymer chains move across energy barriers, finding that hairpin crossings are less favorable than end crossings. The polymer translocation time depends on chain length and temperature, aligning with experimental DNA and polypeptide translocation data.
Area of Science:
- Polymer physics
- Biophysics
- Statistical mechanics
Background:
- Long chain molecules in metastable states face energy barriers.
- Understanding polymer translocation mechanisms is crucial for biological processes and nanotechnology.
Purpose of the Study:
- To analyze the translocation of long polymer chains across a biased double-well potential.
- To compare different crossing mechanisms (end vs. hairpin) and their dependence on molecular length and temperature.
- To relate theoretical findings to experimental observations in DNA and polypeptide translocation.
Main Methods:
- Utilized the Rouse model for polymer dynamics.
- Analyzed barrier crossing mechanisms, including end crossing and hairpin crossing.
- Investigated a special kink solution representing the polymer translocation process.
Main Results:
- Hairpin crossing has a higher free energy of activation and a different pre-exponential factor compared to end crossing.
- Activation energy shows a square root dependence on temperature, deviating from Arrhenius behavior.
- Translocation time depends on chain length (N) and temperature (T) as t(cross) ~ N(2)/T(3/2) (no free energy difference) or t(cross) ~ N/sqrt[T] (with free energy difference).
- Theoretical predictions align with experimental data for DNA translocation through nanopores and polypeptide translocation.
Conclusions:
- The Rouse model provides a framework for understanding polymer translocation across energy barriers.
- The study elucidates the distinct contributions of end and hairpin crossings to translocation kinetics.
- The findings support the applicability of polymer physics models to biological translocation processes and nanotechnology applications.
More Related Videos
06:55Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level
Published on: September 26, 2016
11:27Studying Soft-matter and Biological Systems over a Wide Length-scale from Nanometer and Micrometer Sizes at the Small-angle Neutron Diffractometer KWS-2
Published on: December 8, 2016
Related Concept Videos
02:34Polymers
The word polymer is derived from the Greek words “poly” which means “many” and “mer” which means “parts”. Polymers are long chains of molecules composed of repeating units of smaller molecules, known as monomers. They either occur naturally, such as DNA and proteins, or can be constructed synthetically, like plastics. They have varied structural characteristics, such as linear chains, branched chains, or complex networks, that contribute to the properties that they exhibit. Additionally,...
02:34Polymers
The word polymer is derived from the Greek words “poly” which means “many” and “mer” which means “parts”. Polymers are long chains of molecules composed of repeating units of smaller molecules, known as monomers. They either occur naturally, such as DNA and proteins, or can be constructed synthetically, like plastics. They have varied structural characteristics, such as linear chains, branched chains, or complex networks, that contribute to the properties that they exhibit. Additionally,...
01:01Polymers: Defining Molecular Weight
Unlike small molecules with definite molecular weights, polymers are a mixture of individual polymer chains of varying lengths, each with a unique molecular weight. So, the molecular weight of a polymer is expressed as an average value based on the average size of the polymer chains. The two most common forms of averages used for polymers are the number average molecular weight and weight average molecular weight.
The number average molecular weight (Mn) is the summation of the number...
The number average molecular weight (Mn) is the summation of the number...
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...
01:08Molecular 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...
02:34Polymers
The word polymer is derived from the Greek words “poly” which means “many” and “mer” which means “parts”. Polymers are long chains of molecules composed of repeating units of smaller molecules, known as monomers. They either occur naturally, such as DNA and proteins, or can be constructed synthetically, like plastics. They have varied structural characteristics, such as linear chains, branched chains, or complex networks, that contribute to the properties that they exhibit. Additionally,...