Gradient copolymer, its production and application thereof

A gradient copolymer comprising or consisting of a plurality of polymer components, wherein each of the plurality polymer components independently is an addition polymer of a monomer of formula (I), and/or a mixture of monomers of formula (I),

• or
• each of the plurality of polymer components independently comprises or consists essentially of one or more structural units of formula (I-1),
• wherein a total number of the plurality of polymer components is n, and n is an integer within the closed interval [5, ∞], and in formula (I) or formula (I-1),
• the group R1 is H or
• the group R2 is H or a C1-4 linear or branched alkyl,
• a is 0 or 1,
• the group R′ is H or a group R3,
• the group R3 is a C1-C30 linear or branched alkyl group, and
• wherein an average number of carbon atoms in side chain of the i-th polymer component, as determined by nuclear magnetic resonance, is Xi, wherein i is an integer from 1 to n, and X1<X2< . . . <Xn−1<Xn,
• wherein a weight percentage of the i-th polymer component relative to a total weight of the plurality of polymer components is Yi, and Y1<Y2< . . . <Yj> . . . >Yn−1>Yn,
• wherein j is an integer within the closed interval [(n+1)/4, 3(n+1)/4], and
• Y1+Y2+ . . . +Yi+ . . . +Yn−1+Yn=100%,
• wherein Yi and Xi satisfy the following relationship,
• Y
• i
• =
• f
• ⁡
• (
• X
• i
• )
• =
• 1
• 2
• ⁢
• π
• ⁢
• σ
• ⁢
• e
• -
• (
• X
• i
• -
• μ
• )
• 2
• 2
• ⁢
• σ
• 2
• ,
• (
• IV
• )
• wherein μ is a value within the open interval (12.5, 14.2), and σ is a value within the open interval (0.5, 2).