Nonionic polymers have been used for the control of suspended sol ids and oil, and as an aid to microbiological control programs. These polymers, although electrically neutral, have sites along their structure that are either strongly positive or strongly negative. Because of this separated charge structure, sections of the molecule become either hydrophilic (attached to water) or hydrophobic (repulsed by water). These polymers can be depicted by the following, simple diagram.

In a cooling system, this molecule will become oriented with the hydrophobic end attached to suspended matter, oils, etc. The hydrophilic end then acts as a barrier to other suspended particles preventing their agglomeration. The particles are then easily removed by water velocity and ultimately removed through blowdown.

In a similar manner, a nonionic polymer will also reduce the surface tension of water. In water, cohesive forces will uniformly attract a water molecule on all sides. However, at the surface, water molecules will be attracted down into the water and the surface acts as if it were under compression. This is commonly referred to as surface tension. When certain polymers are added to water, their hydrophobic end is oriented away from the water and they will line up at the surface minimizing the number of water molecules at the surface. Thus, surface tension is reduced. The latter is particularly important because it allows microbiocides to penetrate slime masses more effectively, thereby increasing their efficiency.