Alternative polymers

A less obvious explanation is that the observed residual structure is not due to attractive interactions, but rather to repulsive ones. The steric repulsion between atoms forced to partially overlap is a dominant, if not the dominant, force in all of chemistry. These highly local interactions are known to be important in polymer conformations (Flory, 1969 Ramachandran and Sasisekharan, 1968). For homopolymers or simple alternating polymers, they can often be safely neglected by assuming they confer no net directionality to the chain. Polypeptide chains, however, are chiral and support specific sequences of 20 differently shaped... 

In Alternating polymers, the monomers are produced alternately along the coPolymer chain. -ABABABABAB... 

Alternative Polymer Systems for Proton Exchange Membranes (PEMs)... 

In addition to alternating polymers, other structures are known in which the monomeric units appear in an ordered sequence. Examples are ... 

The technique of alternating polyelectrolyte film construction has also been adapted to incorporate semiconductors into layered films. For example, multilayer films have been constructed by alternately dipping a quartz substrate into a solution of poly(diallylmethylammonium chloride) and then a solution of a stabilized CdS or PbS colloid (41). The layer-by-layer self-assembly of alternating polymer and metal sulfide is at least partially driven by the electrostatic attraction of the cationic polymer and the negative charge of the stabilized MC colloid particles. 

However, such alternative polymers are often too expensive or they have too superior properties, e.g., other than less brittleness that are not needed for the particular application. For these reasons, a good solution is to start with styrene-based copolymers, and to modify them accordingly (2). 

The small reactivity ratio for AN indicates that a growing AN radical is reluctant to react with an AN monomer, but rather will react with a styrene monomer. On the other hand, even when a growing styrene radical reacts rather with an AN monomer, the tendency is not as marked. In the limiting case, if both monomer reactivity rations are going to zero, this effects the formation of strictly alternating polymers. The composition of the polymer can be controlled by the ratio of monomers in the monomer feed. In particular, since one of the monomers will be consumed faster that the other in a discontinuous process, the monomer feed can be adjusted accordingly in the course of polymerization. Also in a continuous process, in a cascade of reaction vessels, monomer can be fed into certain stages. 

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