Models For The Understanding Of Molecularly Imprinted Polymers
thesisposted on 16.04.2019, 13:40 by Todd Cowen
Polymer synthesis can be performed in the presence of template molecule to produce a corresponding cavity, giving a molecularly imprinted polymer (MIP) with affinity for the template. A brief review of the predominant techniques in MIP computational analysis will be given and contrasted with a molecular mechanics/molecular dynamics (MM/MD) alternative, including some examples of how this can be applied. Automated synthesis of MIPs in silico will then be demonstrated as a further development of the MM/MD method, producing polymers by mimicking radical polymerization atomistically. Comparative analysis in the design of a synthetic ephedrine receptor demonstrates that the new method can effectively identify affinity trends and binding site selectivities where analysis of templatemonomer and template-solution systems cannot. Studies of polymer nanoparticle dimensions were then pursued and found to correlate with polymer solubility when expressed as the Flory parameter χs,p. A modified Flory-Huggins based thermodynamic model was then developed for the analysis of the hydrodynamic diameters, and the absolute size of polymer nanoparticles was found to be predictable by varying the polymerization conditions that influence χs,p. The position of the spinodal, associated with a given χs,p equivalent, allows an absolute value, Δχspinodal, to be calculated. The hydrodynamic diameter, D, of nanoparticles at the primarily observed fraction was then found to be dependent on D (nm) = −74Δχspinodal + 367 nm, where Δχspinodal must be positive for successful separation. The polymerization algorithm was then applied to the prepolymerization system in an attempt to improve understanding and prediction of Δχspinodal. From these studies it is concluded that MIP synthesis occurs by a binodal-character phase separation, having implications for the synthetic mechanism. The polymerization algorithm, thermodynamic model, synthetic mechanism and described relationship between polymer diameter and solubility should therefore be useful additions to future analysis.