Gradient copolymer, method for producing same, and use thereof

Provided are a gradient copolymer, a method for producing the same, and use thereof. The gradient copolymer comprises n polymer components or consists of the n polymer components. Each of the n polymer components independently represents an addition polymer of a monomer represented by formula (I) and/or a mixture thereof; or each of the n polymer components independently comprises one or more structural units represented by formula (I-1) or basically consists of one or more structural units represented by formula (I-1). Symbol n represents an integer within a closed interval [5, ∞]. The average number of carbon atoms in a side chain of the ith polymer component by a nuclear magnetic resonance method is X i , the symbol i represents any integer from 1 to n; the relationship equation X 1 ＜X 2 ＜...＜X n-1 ＜X n satifies. The gradient copolymer is capable of exhibiting an excellent lubricating oil pour point depression efficiency or a wide base oil pour point depression adaptability. In the formula (I) or the formula (I-1), each of the groups and numerical values is defined as the same as the specification.