Round 4: Tossup 5

Characteristic ratios can be compiled for these molecules using the rotational isomeric state model. Symmetric “Maltese cross” patterns can be observed under polarized light when these molecules form semicrystalline spherulites (“sfir-ROO-lites”). Solutions of these molecules are considered ideal when the Mark–Houwink exponent (10[1])equals one half and the theta condition is reached. The interaction parameter chi (“kai”) is used to calculate free energies of mixing for solutions of these molecules in the Flory–Huggins model. (10[3])Atactic examples of these molecules (10[1])usually have lowered glass-transition temperatures. Epoxy (10[1])resins are “cured” into the thermoset type of these molecules, which are alternatively formed by step-growth or chain-growth (10[1])methods. For 10 points, name these molecules made of repeating monomers. ■END■ (10[1])

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