<p>This study proposes a polymer analogous reaction-based synthetic strategy to enhance the thermal stability and internal cohesion of acrylic pressure-sensitive adhesives (PSAs), systematically comparing it with conventional copolymerization. Poly(n-butyl acrylate-co-tert-butyl acrylate) (P1) was synthesized via free-radical copolymerization, and functionalized P2 was prepared by introducing DBPA onto the P1 backbone. Additionally, P3 was obtained by incorporating glycidyl methacrylate (GMA), followed by post-modification to yield P4 with DBP-based functional groups. GPC analysis showed that P4 maintained more stable molecular weight control compared to copolymerized samples. TGA revealed that the 10% weight loss temperature T_10% increased with DBP content, demonstrating improved thermal stability. Furthermore, shear strength tests showed that functionalized polymers exhibited 3–4 times higher strength than non-functionalized samples, confirming significantly enhanced internal cohesion. These results suggest that polymer backbone modification via polymer analogous reactions is an effective strategy for simultaneously improving the thermal stability and cohesion of acrylic PSAs.</p>