Properties of Polymers -Isotactic and syndiotactic polymers are stronger and stiffer due to their regular packing arrangement. Anionic intermediate usually gives isotactic or syndiotactic polymers. Free-radical polymerization is nearly random,giving branched atactic polymers. Chapter 26 13Chapter 26 13 Properties of Polymers ▪ Isotactic and syndiotactic polymers are stronger and stiffer due to their regular packing arrangement. ▪ Anionic intermediate usually gives isotactic or syndiotactic polymers. ▪ Free-radical polymerization is nearly random, giving branched atactic polymers