LATERAL SUBSTRATE COMPLETION RATE IN THE LAURITZEN-HOFFMAN SECONDARY SURFACE NUCLEATION THEORY - NATURE OF THE FRICTION COEFFICIENT

In this paper it is demonstrated that, within the context of the Lauri tzen-Hoffman (LH) secondary surface nucleation theory, the nature of t he friction factor governs whether or not a fraction of the total bulk free energy is apportioned to the activated state during secondary nu cleation. The friction coefficient (zeta) associated with reeling the chain onto the growth front, when equated to that measured through sel f-diffusion studies, forces the apportionment factor (psi) to be equal to zero. On the other hand, assuming that zeta is a function of the s hape of the free energy barrier allows psi to take on nonzero values. In the first instance, the ''delta l catastrophe'' is eliminated, wher eas in the second case the ''delta l catastrophe'' is associated with the substrate completion process (in contrast to the classical LH theo ry, which associates it with the deposition of the first stem). It is shown that both occurrences are mathematical artifacts which arise bec ause the apportionment factor is treated as being equivalent for the f irst and all subsequent stems, and thus two different psi's are requir ed. Furthermore, it is suggested that two different expressions for be ta (the transport term) are required for the first versus all subseque nt stems.