  Hydrogen bonding plays a role in the microphase separation behavior of many
block copolymers, such as those used in lithography, where the stronger
interactions due to H-bonding can lead to a smaller period for the
self-assembled structures, allowing the production of higher resolution
templates. However, current statistical thermodynamic models used in
descriptions of microphase separation, such as the Flory-Huggins approach, do
not take into account some important properties of hydrogen bonding, such as
site specificity and cooperativity. In this combined theoretical and
experimental study, a step is taken toward the development of a more complete
theory of hydrogen bonding in polymers, using polyacrylamide as a model system.
We begin by developing a set of association models to describe hydrogen bonding
in amides. Both models with one association constant and two association
constants are considered. This theory is used to fit IR spectroscopy data from
acrylamide solutions in chloroform, thereby determining the model parameters.
These parameters are then employed to calculate the scattering function of the
disordered state of a diblock copolymer with one polyacrylamide block and one
non-hydrogen-bonding block in the random phase approximation. It is then shown
that the expression for the inverse scattering function with hydrogen bonding
is the same as that without hydrogen bonding, but with the Flory-Huggins
parameter $\chi$ replaced by an effective value
$\chi_\text{eff}=\chi+\delta\chi_\text{HB}\left(f\right)$, where the
hydrogen-bonding contribution $\delta\chi_\text{HB}$ depends on the volume
fraction $f$ of the hydrogen-bonding block. We find that models with two
constants give better predictions of bond energy in the acrylamide dimer and
more realistic asymptotic behavior of the association constants and
$\delta\chi_\text{HB}$ in the limit of high temperatures.
