A facile and high yield method for the covalent functionalization of graphene through the free radical addition of a commercially available polymerization initiator, 2,29-azobisisobutyronitrile (AIBN), has been successfully realized. The obtained material was determined to have 1 isobutyronitrile group substituent per 50 carbon atoms.
We report a facile method that combined sol-gel reaction, reversible addition-fragmentation chain transfer (RAFT)/macromolecular design via interchange of the xanthates process and thiol-ene click reaction to prepare monodisperse silica core-poly(N-vinylimidazole) (PVim) shell microspheres of 200 nm in average diameters. First, silica with C = C double bonds was prepared by the sol-gel reaction of 3-(trimethoxysilyl)propyl methacrylates (MPS) with tetraethoxysilane in ethanol; SiO 2 @PVim were subsequently prepared by grafting PVim chain (Mn = 9800 g/mol, polydispersity index = 1.22) to MPS-SiO 2 via the thiol-ene click chemisty. The obtained SiO 2 @PVim microspheres show higher catalytic activity toward the hydrolysis of p-nitrophenyl acetate compared with the PVim homopolymers. The as-prepared composites have been characterized by scanning electron microscopy, transmission electron microscopy, thermal gravimetric analysis and Fourier transform infrared spectrometry analysis.
Well-defined amphiphilic block copolymers, poly(styrene)-b-poly(N-vinylimidazole) (PS-b-PVim), were successfully synthesized by macromolecular design via interchange of the xanthates/reversible addition-fragmentation chain transfer (RAFT) polymerization. The structure of the copolymer based on Vim can be well controlled, and the molecular weight distribution was relatively narrow (PDI = 1.24). The size and morphology of the aggregates of the amphiphilic copolymers were investigated by dynamic light scattering and transmission electron microscope, the results implied that the uniform spheroidal micelles consisting of PS core and PVim corona were assembled, and the catalytic activities of PS-b-PVim for the hydrolysis of p-nitrophenyl acetate at different temperatures were also investigated by highperformance liquid chromatograph (HPLC); the catalytic activities of diblock copolymers were prominently improved compared with that of PVim homopolymers. Moreover, the catalytic activities of the copolymers followed the Arrhenius behavior in the wide experimental temperature range.
The wetting properties of superhydrophobic surfaces have received worldwide and tremendous attention [1] since the dual hierarchical structure of the lotus leaf was discovered [2]. Lotus-Leaf-like superhydrophobic surfaces, exhibit an amazing property for not only being wetted by water leading to a self-cleaning effect [3], but also for their great advantages in applications. In recent years, superhydrophobic surfaces are widely used in the human body implant materials [4], microfluidic tools [5], Calix azacrown [6], tunable optical lenses [7], labon-chip systems [8]. The wettability of the surface is influenced by its chemical composition and morphology [9], because chemical composition determines the surface free energy, and a lower surface energy leads to higher hydrophobicity. Additionally, the hierarchical structure (micro roughness covered with nano roughness) was not only necessary for a high contact angle (CA) but essential for the stability of the water-solid and water-air interfaces [10] Received 1 January 2014; accepted in revised form 1 April 2014Abstract. A dual-switchable surface between hydrophobic and superhydrophobic has been fabricated successfully by combining reversible addition-fragmentation chain transfer polymerization (RAFT) polymeric technology and thiol-NCO click chemistry. Well-defined block copolymer, poly(7-(6-(acryloyloxy) hexyloxy) coumarin)-b-poly(N-Isopropylacryl amide), was synthesized by RAFT, and then the block copolymer was grafted onto the surface of SiO 2 modified by toluene disocynate (TDI) via thiol-NCO click chemistry. The results of nuclear magnetic resonance (NMR) and Fourier Transform Infrared (FTIR) spectroscopies confirmed that the block copolymer (Number average molecular weight (M n ) = 9400, polydispersity index (PDI) = 1.22) has been synthesized successfully. The static contact angle (CA) of the surface prepared by SiO 2 /P (7-6-AC)-b-PNIPAAm switches from 98±2 to 137±2° by adjusting the temperature. Furthermore, the contact angle can also oscillate between 137±2 and 157±2° on the irradiation of UV light at 365 and 254 nm, respectively. The dual-switchable surfaces exhibit high stability between hydrophilicity and superhydrophobicity. Therefore, the method provides a new method to fabricate the dual-stimuli-responsive surface with tunable wettability, reversible switching, and also be easily extended to other dual-responsive surfaces. This ability to control the wettability by the adjustment of the temperature and UV light has applications in a broad range of fields.
Background Continuous glucose monitoring (CGM) can help manage diabetes mellitus (DM) and prevent hypoglycemia. This study aimed to evaluate the performance and usability of a novel SiJoy GS1 CGM system. Methods This multicenter trial enrolled participants with DM. Based on the comparison of glucose values measured by SiJoy GS1 CGM and venous blood glucose test, the 20/20% consistency and mean absolute relative difference (MARD%) were calculated, as well as Clarke and consensus error grid analysis. Product usability was evaluated by questionnaire completed by participants. Any occurrence of adverse events (AE) was documented. Results Seventy participants were included in the study. The mean age of participants was 41.5 ± 13.2 years, among which 29 (42.0%) were male, with the DM course of 8.6 ± 7.5 years. A total of 39 (56.5%) of them had type 1 DM, 24 (34.8%) had type 2 DM, and 6 (8.7%) were others for DM. The 20/20% consistency achieved 91.82%, which was higher than the target 65%. The percentage of A + B zones of Clarke and consensus error grid was 99.22% and 99.90%, respectively. The MARD value was 8.83% ± 4.03%. The mean score of usability questionnaire was 86.59 ± 5.17 out of 90. AE were observed in only one participant (mild fever), and no severe AEs occurred. Conclusions The SiJoy GS1 CGM system achieved satisfactory performance and usability. No severe AEs occurred and mild AE was reported in only one case.
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