To clarify the influence of molecular weight of siloxane macromonomer on phase separation morphology, oxygen permeability, and mechanical properties, silicone hydrogels were prepared by copolymerizing mixtures of methacrylate-terminated siloxane macromonomer (MTSM), silicon-containing monomers tris(trimethylsiloxy)-3-methacryloxpropylsilane, and three hydrophilic monomers N,N-dimethylacrylamide, N-vinylpyrrolidone, and hydroxypropyl methacrylate. The number of Si–O–Si repeating units was equal in every silicone hydrogel while the molecular weight of MTSM ranged from 1000 to 10000 g/mol. The oxygen permeability coefficient (Dk), equilibrium water content (EWC), light transmittance, mechanical properties, and internal morphologies of obtained silicone hydrogels were characterized, and their relationships were discussed in detail. The results showed that the Dk value increased first and then decreased with the chain length of MTSM increasing. The EWC presented an increasing trend and the light transmittance decreased with the increase of MTSM chain length. The elongation increased while the modulus and the tensile strengths of the silicone hydrogels decreased along with the MTSM molecular weight increasing. The internal morphologies of the silicone hydrogels were observed by transmission electron microscope. The results indicated that the silicone hydrogels presented different phase separation structures depending on the molecular chain length of MTSM. The continuous silicone phase formed and made significant contributions to high Dk value as the molecular chain length of MTSM was moderate. Besides, a model was proposed to explain the effect mechanism of the MTSM chain length on the oxygen permeability and the EWC. This work provided a facile method to preparing the silicone hydrogel materials with desirable water absorption and high oxygen permeability by adjusting the molecular weight of macromonomers.

•Fluorescence quenching has been found in the PPP coupled to silver nanocap array.•Fluorescence quenching goes with the red-shifted PL peak of PPP in the hybrid.•Decreased Raman signal corresponds to increased PL intensity of PPP in the hybrid.•Inter-ring CC stretching vibration is connected with the fluorescence quenching.The optical properties of poly(2,5-dioctyloxy-p-phenylene) (DOO-PPP) coupled to a silver nanocap array are investigated by Raman and photoluminescence spectra. The emission intensity of the DOO-PPP coupled to the silver nanocap array is much weaker than that of the DOO-PPP film due to the fluorescence quenching of the silver nanocap array. In contrast with the freshly prepared sample, the fluorescence quenching efficiency of the silver nanocap array is obviously decreased for the sample exposed in air; correspondingly, the Raman intensity at 1609 cm−1 is markedly decreased, which is characteristic Raman peak of the inter-ring CC stretching vibration in the conjugated polymer. The experimental results indicate that the inter-ring CC stretching vibration plays an important role for the fluorescence quenching in the DOO-PPP coupled to the silver nanocap array.