Random copolymer and pinning composition comprising the same

A random copolymer comprising a unit represented by Formula 1 below and a unit represented by Formula 3-1 or 4 below:

• wherein, in Formula 1, R is hydrogen or an alkyl group, A is an oxygen atom, a sulfur atom, —S(═O)2—, a carbonyl group, —C(═O)—X1— or —X1—C(═O)—, where X1 is an oxygen atom or a sulfur atom, B is an alkylene group, an alkenylene group or an alkynylene group, and C is represented by Formula 2 below,
• wherein, L is a single bond or an oxygen atom,
• wherein, in Formula 3-1, R is hydrogen or an alkyl group, X is a single bond, R1 to R5 are each independently hydrogen, an alkyl group, a haloalkyl group or a halogen atom, and at least one halogen atom is included in at least one of R1, R2, R3, R4, or R5,
• wherein, in Formula 4, R is hydrogen or an alkyl group, and X is a single bond, an oxygen atom, —S(═O)2—, a carbonyl group, an alkylene group, an alkenylene group, an alkynylene group, —C(═O)—X1′—, or —X1′—C(═O)—, where X1′ is an oxygen atom, a sulfur atom, an alkylene group, an alkenylene group or an alkynylene group, and Y is a monovalent substituent including a ring structure to which a linear chain having eight or more chain-forming atoms is linked.