A series of linear and randomly branched poly(alkyl methacrylate)s with pendant 2-ureido-4[1H]-pyrimidone (UPy) groups, which form quadruple hydrogen bonds, were synthesized, and the role of molecular topology on intermolecular hydrogen bonding was investigated. In solution rheological studies of poly(methyl methacrylate-co-UPy methacrylate) (PMMA-co-UPyMA) copolymers, a branched copolymer in the nonassociated state displayed a larger entanglement concentration (Ce) than a linear copolymer of equal molar mass. However, Ce of the branched copolymer approached the Ce of the linear analogue as the degree of hydrogen bond associations increased in solution, which suggested the reduced chain dimensions of the branched structure were overcome upon intermolecular association of the UPy groups. A series of linear and branched poly(2-ethylhexyl methacrylate-co-UPy methacrylate) (PEHMA-co-UPyMA) copolymers with 0−10 mol % UPy were utilized for melt rheological studies. A decrease in zero shear viscosity (η0) and re...