quick question - independent?

A rigid rod polymer chain is a chain for which all bonds are parallel and equal, i.e. ri = lu for all i=1…N, where l is the constant bond length.

I'm trying to calculate the mean square end to end to distance, but could some one please tell me whether the bonds are independent or not as I'm not sure which method to approach...

Thanks in advance!

Reply 1

cpchem

If we assume we have a random-flight polymer (i.e. all bonds independent), then the mean square end-to-end distance is given by

R^2=Nl^2

, where R is the mean square end-to-end distance, N the number of monomers and l the monomer length.

Reply 2

cpchem

See page 33 of this lecture handout.

Reply 3

sexyzebra

Thanks for the reply cpchem, I have worked out the answer you gave,

R^2 = Nl^2

but did this assuming the bonds are independent. How can you be sure they are indepedent, and am I right to assume this?

Thanks again.

Reply 4

cpchem

OK, it's generally not correct to assume independent motion of bonds. The approach taken is to define a statistical segment of length s, of s/l bonds or monomers.