This work investigated the efficient routes for the fabrication of semi-permeable thin films for desalination using plasma polymerization technology. Acrylic acid (AAc) was selected as a precursor for plasma polymerization due to its hydrophilic properties and potential for low fouling functionalization and ability to form flexible, filtration-ready films. The plasma polymerized AAc films were deposited on the top of poly(sulfone) ultrafiltration (PSf UF) membranes to enhance the selectivity of the composite membranes. Different plasma modes such as continuous wave (CW) or pulsed plasma were applied to overcome the brittleness issue. Such narrow pore size UF membranes, with pores less than 10 nm, were further used for rejecting perfluoroalkyl substances (PFASs), a class of persistent environmental chemicals, also known as an emerging threat to public health and the environment. The selectivity and antifouling behavior of the tight UF membranes were investigated against four PFASs differentiated by molecular weight. The tight UF membranes have shown approximately 20 % higher rejection than the pristine PSf. Although the rejection rate was enhanced proportionally with the size of PFAS compounds, membrane fouling became severe as the size of PFAS became close to the molecular cut-off size of the composite membranes. The surfaces of the tight UF plasma modified membranes were more hydrophilic with a water contact angle of 15.1° and negatively charged streaming potential of −31 mV at pH 8, which contributed to the lowest total permeance decline ratio and highest flux recovery rate compared with pristine PSf during each filtration test. The outcome of this study has opened more opportunities for the application of the plasma polymerized membranes for gas separation, water treatment, fuel cells, biomedical devices, and protective coatings.