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Questions and Answers
The end-to-end distance for a poly(isobutylene) chain of molecular weight 105 will be the same for fully extended chain and statistical coil at 25 °C.
The end-to-end distance for a poly(isobutylene) chain of molecular weight 105 will be the same for fully extended chain and statistical coil at 25 °C.
False (B)
For flexible chains without long-range interactions, the value of n is 0.5-0.6.
For flexible chains without long-range interactions, the value of n is 0.5-0.6.
False (B)
The average quadratic distance between ends for a monodispersed polyethylene sample is directly proportional to its molecular weight.
The average quadratic distance between ends for a monodispersed polyethylene sample is directly proportional to its molecular weight.
False (B)
The radial distribution function, W(r), expresses the probability of finding the end on the surface of a spherical cap of radius r, having a minimum.
The radial distribution function, W(r), expresses the probability of finding the end on the surface of a spherical cap of radius r, having a minimum.
In the context of short-range interactions, an excluded volume of 0 indicates perfect solvation.
In the context of short-range interactions, an excluded volume of 0 indicates perfect solvation.
A distorted propeller chain with n = 0.9 is more flexible than a chain with n = 0.6.
A distorted propeller chain with n = 0.9 is more flexible than a chain with n = 0.6.
Short-range interactions occur between units that are in close proximity to each other.
Short-range interactions occur between units that are in close proximity to each other.
The excluded volume depends on the molecular weight, the degree of solvation, and the temperature.
The excluded volume depends on the molecular weight, the degree of solvation, and the temperature.
In the case of synthetic polymers and denatured natural macromolecules, intramolecular forces are often strong.
In the case of synthetic polymers and denatured natural macromolecules, intramolecular forces are often strong.
Random coil conformations have a specific and defined structure due to strong intramolecular forces.
Random coil conformations have a specific and defined structure due to strong intramolecular forces.
Short-range interactions are a consequence of the steric impediment imposed by the effective volume occupied by each unit.
Short-range interactions are a consequence of the steric impediment imposed by the effective volume occupied by each unit.
Statistical coil dimensions include mean end-to-end distance and average radius of gyration.
Statistical coil dimensions include mean end-to-end distance and average radius of gyration.
In the concept of statistical coil, the rigid conformation is the exclusive conformation adopted by the macromolecule.
In the concept of statistical coil, the rigid conformation is the exclusive conformation adopted by the macromolecule.
Short-range interactions occur intermolecularly between distant units, i + l, i + 2, etc.
Short-range interactions occur intermolecularly between distant units, i + l, i + 2, etc.
Short-range interactions are not influenced by factors like bond angles and steric impediments.
Short-range interactions are not influenced by factors like bond angles and steric impediments.
Steric impediments play a role in causing short-range interactions between molecules.
Steric impediments play a role in causing short-range interactions between molecules.
In the statistical coil concept, the molecular state is highly ordered and predictable.
In the statistical coil concept, the molecular state is highly ordered and predictable.
The short-range interactions primarily involve long-distance electrostatic interactions between molecules.
The short-range interactions primarily involve long-distance electrostatic interactions between molecules.
Study Notes
Proportionality of Distance between Extremes and Molecular Weight
- The distance between extremes has a proportionality with molecular weight, influenced by favorable solvation, excluded volume, and unfavorable solvation.
- Excluded volume = 0 corresponds to a non-perturbed state (T = Θ).
Excluded Volume and Molecular Weight
- For flexible chains without long-range interactions, n = 0.5.
- For flexible chains with interactions, n = 0.5-0.6.
- For distorted propellers, n = 0.6-0.9.
- For rigid chains or helixes, n = 1.
Distribution Function
- The end-to-end distance follows a Gaussian distribution defined by the probability density function W(r).
- The radial distribution function W(r) 4Ï€r2 expresses the probability of finding the end on the surface of a spherical cap of radius r.
Statistical Coil Dimensions
- For synthetic polymers and denatured natural macromolecules, intramolecular forces are very weak.
- Many possible conformations have the same energy and are equally likely.
- Statistical coil dimensions include mean end-to-end distance and average radius of gyration.
Random Coil Model
- The random coil model is constructed using links with a length equivalent to the bond.
- Each link joins the previous one adopting a random orientation, except for the restrictions imposed by the chemical bonds.
- The result is a random coil conformation.
Molecular Interactions
- Short-range interactions occur intramolecularly between nearby units and are caused by bond angles, rotational barriers, steric impediments, and electrostatic interactions.
- Long-range interactions occur between units separated from each other and are a consequence of the steric impediment imposed by the effective volume occupied by each molecule (excluded volume).
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Description
Test your knowledge on polymer conformations and the proportionality of distance between extremes with molecular weight. This quiz covers concepts such as solvation, excluded volume, distribution functions, and conformation characteristics for flexible and rigid chains.
