Core-shell structured SiO2/poly（N-isopropylacrylamide） （SiO2/PNIPAM） microspheres were successfully fabricated through hydrolysis and condensation reaction of tertraethyl orthosilicate （TEOS） on the surface of P...Core-shell structured SiO2/poly（N-isopropylacrylamide） （SiO2/PNIPAM） microspheres were successfully fabricated through hydrolysis and condensation reaction of tertraethyl orthosilicate （TEOS） on the surface of PNIPAM template at 50 ~C. The PNIPAM template can be easily removed by water at room temperature so that SiO2 hollow microspheres were finally obtained. The transmission electron microscope and scanning electron microscope observations indicated that SiO2 hollow microspheres with an average diameter of 150 nm can be formed only if there are enough concentration of PNIPAM and TEOS, and the hy- drolysis time of TEOS. FTIR analysis showed that part of PNIPAM remained on the wall of SiO2 because of the strong interaction between PNIPAM and silica. This work provides a clean and efficient way to prepare hollow microspheres.展开更多
We studied the dielectric properties of organosilicon-containing helical cyclopolymer PbMA which consists of PMMA main chains and tetramethyldisiloxane side rings. PbMA formed films with excellent uniformity through s...We studied the dielectric properties of organosilicon-containing helical cyclopolymer PbMA which consists of PMMA main chains and tetramethyldisiloxane side rings. PbMA formed films with excellent uniformity through spin-coating onto highly n-doped silicon （n-Si） wafers for constructing devices of dielectric measurements, on which the dielectric properties and I-V characteristics of PbMA were studied. PbMA has a much lower dielectric constant （lower than 2.6） in the frequency range of 10-105 Hz, and better thermal stability than PMMA does. I-V data showed that the metal/PbMA/n-Si devices have different conducting directions, depending on whether Au or Al deposited over PbMA layers.展开更多
We proposed a novel method of fabricating polydimethylsiloxane (PDMS) microfluidic chip polymer master molds in this paper. The method mainly includes two steps. First, a stainless steel slice was laser etched to form...We proposed a novel method of fabricating polydimethylsiloxane (PDMS) microfluidic chip polymer master molds in this paper. The method mainly includes two steps. First, a stainless steel slice was laser etched to form a metal model. Then, the organic solution of poly(methyl methacrylate) (PMMA) was casted onto the metal model to fabricate the PMMA master which subsequently would be used to fabricate PDMS chips. We systematically researched different laser parameters influencing the surface status of microchannels and obtained optimized etching parameters. We investigated and optimized the organic solution composition of PMMA while casting chip masters, and developed a method to form fine polymer masters using two different viscosity solutions to cast the model in turn, and studied the repeatable replication. Then, we investigated physical performance of this chip and evaluated the practicability by analyzing Rhodamine B. Compared with present methods, the proposed method does not need photolithography on photoresistant and chemical etching. The entire fabricating progress is simple, fast, low-cost and can be controlled easily. Only several minutes are required to make a metal model, 3 hours for a PMMA master, and one day for PDMS chips.展开更多
文摘Core-shell structured SiO2/poly（N-isopropylacrylamide） （SiO2/PNIPAM） microspheres were successfully fabricated through hydrolysis and condensation reaction of tertraethyl orthosilicate （TEOS） on the surface of PNIPAM template at 50 ~C. The PNIPAM template can be easily removed by water at room temperature so that SiO2 hollow microspheres were finally obtained. The transmission electron microscope and scanning electron microscope observations indicated that SiO2 hollow microspheres with an average diameter of 150 nm can be formed only if there are enough concentration of PNIPAM and TEOS, and the hy- drolysis time of TEOS. FTIR analysis showed that part of PNIPAM remained on the wall of SiO2 because of the strong interaction between PNIPAM and silica. This work provides a clean and efficient way to prepare hollow microspheres.
基金This work was supported by the National Natural Science Foundation of China （No.51673181）.
文摘We studied the dielectric properties of organosilicon-containing helical cyclopolymer PbMA which consists of PMMA main chains and tetramethyldisiloxane side rings. PbMA formed films with excellent uniformity through spin-coating onto highly n-doped silicon （n-Si） wafers for constructing devices of dielectric measurements, on which the dielectric properties and I-V characteristics of PbMA were studied. PbMA has a much lower dielectric constant （lower than 2.6） in the frequency range of 10-105 Hz, and better thermal stability than PMMA does. I-V data showed that the metal/PbMA/n-Si devices have different conducting directions, depending on whether Au or Al deposited over PbMA layers.
基金Funded by the Natural Science Foundation of China (No. 20775096)
文摘We proposed a novel method of fabricating polydimethylsiloxane (PDMS) microfluidic chip polymer master molds in this paper. The method mainly includes two steps. First, a stainless steel slice was laser etched to form a metal model. Then, the organic solution of poly(methyl methacrylate) (PMMA) was casted onto the metal model to fabricate the PMMA master which subsequently would be used to fabricate PDMS chips. We systematically researched different laser parameters influencing the surface status of microchannels and obtained optimized etching parameters. We investigated and optimized the organic solution composition of PMMA while casting chip masters, and developed a method to form fine polymer masters using two different viscosity solutions to cast the model in turn, and studied the repeatable replication. Then, we investigated physical performance of this chip and evaluated the practicability by analyzing Rhodamine B. Compared with present methods, the proposed method does not need photolithography on photoresistant and chemical etching. The entire fabricating progress is simple, fast, low-cost and can be controlled easily. Only several minutes are required to make a metal model, 3 hours for a PMMA master, and one day for PDMS chips.
