Separation　membranes　with　high　perm-selectivity,　good　stability　and　anti-fouling　properties　are　critical　for　water　treatment　and　green　chemical　processing.　We　synthesized　soft　polymeric　particles,　zwitterionic　nanogels　(ZNGs),　using　a　facile　and　straightforward　surfactant-free　emulsion　polymerization.　Novel　thin-film　nanocomposite　membranes　(TFNMs)　containing　ZNGs　were　prepared　by　interfacial　polymerization　using　piperazine　and　trimesoyl　chloride.　The　ZNG　particles　were　well　compactible　with　the　polyamide　membrane　matrix,　rendering　high　separation　performance.　Both　the　water　permeability　and　solute　selectivity,　e.g.,　J(H2O)　=　106.3　L　m(-2)　h(-1)　MPa-1,　R-Na2SO4　=　97.8%,　R-NaCl　=　31.6%,　were　increased　compared　to　conventional　polyamide　thin-film　membranes.　The　mechanism　of　this　high　performance　was　firstly　studied　in　depth　at　molecular　level　with　the　positron　annihilation　spectroscopy.　The　existence　of　nanoscale　pores　in　ZNGTFNMs　provide　preferential　flow　paths　for　water　molecules,　thus　fostering　the　exceptional　perm-selectivity　coupled　with　remarkable　stability　and　anti-fouling　properties.　Moreover,　the　as-prepared　ZNGTFNMs　were　used　for　antibiotics　desalination　and　concentration.　For　example,　the　antibiotic　erythromycin　content　in　mixed　feed　solution　increases　almost　linearly　from　100　to　360　mg　L-1　(the　value　is　3.5　times　higher　than　the　original　concentration)　within　6　h　continuous　operation.　Therefore,　this　ZNG　embedded　TFNMs　exhibit　great　potential　applications　in　water　purification　and　salts/organics　separation.