A series of highly fluorinated polymers were synthesized by copolymerization of 2,3,4,5,6-pentafluorostyrene (PFS) and fluorinated styrene derivate monomer (FSDM). Their chemical structure were confirmed by H-1 NMR, C-13 NMR, and F-19 NMR spectra. The refractive index and cross-linking density of the polymers can be tuned and controlled by monitoring the feed ratio of comonomers. A series of negative-type low-molecular-weight fluorinated photoresists (NFPs) were prepared by composing of fluorinated polystyrene derivates (FPSDs), diphenyl iodonium salt as a photoacid generator (PAG) and solvent. The polymer films prepared from NFP by photocuring exhibited excellent chemical resistance and thermal stabilities (T-d ranged from 230.5 to 258.1 degrees C). A clear negative pattern was obtained through direct UV exposure and chemical development. For waveguides without upper cladding, the propagation loss of the channel waveguides was measured to be 0.25 dB/cm at 1550 nm. 0 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 762-769, 2011