A simple and novel method is firstly reported for controlling coffee ring structure on polystyrene（PS）film surface by O2 plasma. O2 plasma treatment leads to the wettability change of PS surface from hydrophobic to hydrophilic. For hydrophilic PS surface the coffee ring structure is avoided relying on the motion of contact line（CL） while SiO2 microspheres are left. The motion of the CL is produced based on the viscosity and Marangoni effect with the addition of polymer additives. For hydrophobic PS surface coffee ring structure still persists even with polymer additives because SiO2 microspheres transfer with the motion of the CL at the beginning of droplet evaporation and accumulate at the droplet edge at late stage with the pinning of the CL. As a result, uniform and macroscale SiO2 microspheres deposition without coffee ring structure and SiO2 microspheres deposition with coffee ring structure are controlled by O2 plasma. This method provides a new way to tune coffee ring structure with smart surface and may be potentially useful for a range of application at material deposition and diagnosing diseases.
Li-Ying CuiYu YanXin-Yu ZhaoCun-Long YuYing MaBai Yang
Copolymers of methyl methacrylate （MMA） and acrylate terminated poly（ethylene oxide-co-ethylene carbonate） （PEOC） macromonomer （PEOCA） were synthesized, and the degradation of the polymers was investigated by use of quartz crystal microbalance with dissipation （QCM-D）. It is shown that the polymeric surface exhibits degradation in seawater depending on the content of the side chains. Field tests in seawater show that the surface constructed by the copolymer can effectively inhibit marine biofouling because it can be self-renewed due to degradation of the copolymer.
A series of double-hydrophilic double-grafted PMA-g-PEG/PDMA copolymers, which contained poly（methacrylate） （PMA） as backbone, poly（ethylene glycol） （PEG） and poly（N,N-dimethylacrylamide） （PDMA） as side chains synthesized successfully by using reversible addition-fragmentation chain transfer （RAFT） polymerization and atom transfer radical polymerization （ATRP）, were used as physical coatings for the evaluation of protein-resistant properties by capillary electrophoresis （CE）. Electroosmotic flow （EOF） measurement results showed that the PMA-g-PEG/PDMA copolymer coated capillaries could suppress electroosmotic mobility in a wide pH range （pH = 2.8-9.8） and EOF mobility decreased with the increase of copolymer molecular mass and PDMA content. At the same time, protein recovery, theoretical plate number of separation and repeatability of migration time demonstrated that antifouling efficiency was improved with the increase of molecular mass and PEG content.
Lin TanJin-xing XingFu-hu CaoLi-juan ChenChong ZhangRong-hua Shi王延梅
