Preparation method of (co)oligomer or (co)polymer by in-situ polymerization of monoethylenically unsaturated monomer and oligomer or polymer secondary amine to control molecular weight and molecular structure

PURPOSE: Provided is a method for preparing a (co)oligomer or a (co)polymer having a controlled molecular weight, a controlled molecular weight and a narrow polydispersity at a relatively low temperature and for a short time. CONSTITUTION: The method comprises the steps of mixing at least one monoethylenically unsaturated monomer represented by HR1C=CR2R3, at least one oxidant, at least one polymer or oligomer represented by the formula 1, and optionally a free radical initiator; and heating the mixture at a temperature of 0-220 deg.C, wherein R1, R2 and R3 are independently H, a C1-C20 alkyl group, a C1-C20 cycloalkyl group, a C6-C24 aryl group, a halogen atom, a cyano group, a C1-C20 alkyl ester group, a C1-C20 cycloalkyl ester group, a C1-C20 alkylamide group, a C1-C20 cycloalkylamide group, a C6-C24 aryl ester group or a C6-C24 arylamide group; Y is an organic residue based on the monomer corresponding to HR1C=CR2R3; m is an integer of 1-50; n is an integer of 1-300; I1 is an initiator; and R4 and X are a secondary or tertiary carbon atom and are independently selected from the group consisting of a C1-C18 alkyl group, a C2-C18 alkenyl group, a C2-C18 alkynyl group, a C3-C12 cycloalkyl group, a C3-C12 hetero cycloalkyl group or a C6-C24 aryl group unsubstituted or substituted with NO2, a halogen atom, an amino group, a hydroxyl group, a cyano group, a carboxyl group, a ketone group, a C1-C4 alkoxy group, a C1-C4 alkylthio group or a C1-C4 alkylamino group.