A bischloroformate composition is represented by a formula (1) below, contains a plurality of Ar components, and has an average number of monomer units (m1), which is calculated by an expression (Numerical Expression 1) below, ranging from 1.0 to 1.99. The plurality of Ar components are each independently Ar.sub.1 or Ar.sub.2. The plurality of Ar components include at least one Ar.sub.1 and at least one Ar.sub.2. Ar.sub.1 is a group represented by a formula (2) below. Ar.sub.2 is a group represented by a formula (3) below. A molar composition ratio represented by Ar.sub.1/(Ar.sub.1+Ar.sub.2) ranges from 45 mol % to 99 mol %. ##STR00001## average number of monomer units (m1)=1+(Mav−M1)/M2 (Numerical Expression 1)

A bischloroformate composition is represented by a formula (1) below, contains a plurality of Ar components, and has an average number of monomer units (m1), which is calculated by an expression (Numerical Expression 1) below, ranging from 1.0 to 1.99. The plurality of Ar components are each independently Ar.sub.1 or Ar.sub.2. The plurality of Ar components include at least one Ar.sub.1 and at least one Ar.sub.2. Ar.sub.1 is a group represented by a formula (2) below. Ar.sub.2 is a group represented by a formula (3) below. A molar composition ratio represented by Ar.sub.1/(Ar.sub.1+Ar.sub.2) ranges from 45 mol % to 99 mol %. ##STR00001## average number of monomer units (m1)=1+(Mav−M1)/M2 (Numerical Expression 1)

Provided are polymers having a repeating unit including at least one astaxanthin moiety. Also provided are processes for preparing the polymers and various uses thereof.

A bischloroformate composition is represented by a formula (1) below, contains a plurality of Ar components, and has an average number of monomer units (m1), which is calculated by an expression (Numerical Expression 1) below, ranging from 1.0 to 1.99. The plurality of Ar components are each independently Ar.sub.1 or Ar.sub.2. The plurality of Ar components include at least one Ar.sub.1 and at least one Ar.sub.2. Ar.sub.1 is a group represented by a formula (2) below. Ar.sub.2 is a group represented by a formula (3) below. A molar composition ratio represented by Ar.sub.1/(Ar.sub.1+Ar.sub.2) ranges from 45 mol % to 99 mol %.

##STR00001## average number of monomer units (m1)=1+(MavM1)/M2 (Numerical Expression 1)

A high refractive index optical coating made by forming a solid thin layer of a polymer such as P4VP by a process such as iCVD and quaternizing and halogenating the solid layer with vaporized CH.sub.2I.sub.2, CH.sub.3I, and/or CH.sub.2Br.sub.2 to thereby form a resulting film that has a greatly increased refractive index and other desirable optical and other properties.

A high refractive index optical coating made by forming a solid thin layer of a polymer such as P4VP by a process such as iCVD and quaternizing and halogenating the solid layer with vaporized CH.sub.2I.sub.2, CH.sub.3I, and/or CH.sub.2Br.sub.2 to thereby form a resulting film that has a greatly increased refractive index and other desirable optical and other properties.