Polytetrafluoroethylene (PTFE) latex nanoparticles were subjected to modification with Poly (4-vinylpyridine) (P4VP) by in situ seeded emulsion polymerization technique using regular [sodium dodecyl sulfate (SDS)] and fluorinated [Potassium heptadecafluoro-1-octanesulfonate (PFS)]surfactants. The as prepared PTFE- (P4VP/surfactant complex) composite latex nanoparticles were characterized for structure, morphology, and thermal properties and a comparison of particles obtained by PFS and SDS was done with different W/W ratios of PTFE and 4VP monomer. The composites have shown a multistep degradation pattern that may be attributed to the P4VP, surfactant and PTFE backbone degradation. Lowering of crystal-crystal transition temperature of PTFE and increase in the glass transition temperature of the P4VP/PFS or SDS complexes was noticed in all the composites suggesting a homogeneous modification. Thus, a simple and easy way to modify PTFE has been reported which could be subsequently complexed with metal salts such that stringent high energy pretreatment methods like plasma, ozone, or irradiation techniques could be avoided. POLYM. ENG. SCI., 55:499-505, 2015. (c) 2014 Society of Plastics Engineers