Self-penetration

Self-penetration occurs when the smallest topological rings in a single network are penetrated by rods of the same network. The smallest rings refer to the shortest circuits possible which include a given pair of links from the node(s). These are calculated for all possible pairs of links from all possible nodes, and thus they are not necessarily all of the same size. If interpenetration can be considered as polymeric versions of molecular catenanes and rotaxanes, then self-penetration is the polymeric equivalent of a molecular knot. Some examples are given below.

Self-penetration in a 3,6-connected net
Catenated rings from a single (8,4) net