查看更多>>摘要：Bypass or replacement surgery is required in patients with chronic atherosclerotic artery occlusions. In the absence of an autogenous vein, synthetic polytetra-fluoroethylene prostheses can be used. However, these prostheses have shown unsatisfactory bypass grafting results in small-diameter arteries less than 6 mm in diameter. In addition, xenogeneic vessels and vascular prostheses made from biopolymers tend to have poor mechanical strength. The development of vascular prostheses to replace small-diameter vessels is therefore necessary because their hemodynamic properties provoke graft thrombosis. This article provides an overview of the biode- gradable synthetic polymers that are used for the experimental fabrication of small-diameter vascular prostheses. Information on the physicochemical properties of various biodegradable synthetic polymers is presented, and there is also a discussion of the methods capable of increasing the hemo- and biocompatibility of the synthetic materials. Currently the most studied polymers in vascular tissue engineering are polyhydroxybutyrate, polyglycolic acid, polycaprolactone, polyurethane and their corresponding copolymers. The use of copolymers and hybrid materials makes it possible to combine the desirable properties of different polymers. Among these polymers, the polyurethanes are the most promising for the development of small-diameter vessel engineering since their structure can provide different rates of biodegradation, strength, and elasticity.
查看更多>>摘要：The polycaprolactone (PCL)-b-polyethylene glycol (PEG) oligomer (Oli) and its derivative containing ionic elements (ILs) were used as interfacial compatibilizers and regulators, and the polylactic acid (PLA)/PCL/Oli and PLA/PCL/ILs blends were prepared by solution blending. The effects of Oli and ILs on the phase interfacial properties, aggregated structure, crystallization and mechanical properties of PLA/PCL blends were systematically studied. The results show that the ILs with strong interfacial emulsification ability can improve the dispersion of PCL in PLA matrix, and enhance the two-phase interfacial adhesion. When the content of ILs is 5 %, ion clusters can form and alleviate the restricted crystallization of PCL, and promote the segment movement of PLA through the non-covalent bonding of ionic elements. So the crystallization ability of PLA and PCL improve simultaneously. ILs have a strong regulatory effect on the phase interfacial morphology and aggregated structure of PLA/PCL blends, and the PLA/PCL blends containing high content of 5 % ILs can significantly improve the mechanical properties of PLA/PCL blends.
查看更多>>摘要：Silicone hydrogel contact lenses (SiH CLs) covalently grafted with a high-water-content copolymer layer, poly(2-methacryloyloxyethyl phosphorylcholine-co-2-hydroxyethyl acrylate) [P(MPC-co-HEA)], were fabricated, and their physical properties were investigated. SiH CLs were first prepared by radical copolymerization of a siloxane monomer and hydrophilic comonomers, and they were exposed to oxygen plasma to create peroxide groups on the lens surfaces. By letting peroxide-containing (O-2-plasma-treated) SiH CLs act as a thermal free radical initiator, the P(MPC-co-HEA) layer with a water content of approximately 87% could be incorporated onto the surface by graft copolymerization between the lenses and mixed monomers (MPC and HEA). A P(MPC-co-HEA)-grafted SiH CL showed a contact angle of 49.9 degrees, decreased from that of a pristine SiH CL (89.6 degrees). The oxygen permeability of the P(MPC-co-HEA)-grafted SiH CL was recorded to be 54.46 barrer, almost the same as that of the pristine SiH CL (56.01 barrer). Meanwhile, the optical transmittance, tensile strength, and thermal characteristics of the P(MPC-co-HEA)-grafted SiH CL did not deteriorate following the O-2 plasma treatment and graft copolymerization.
查看更多>>摘要：Based on the anthracene-pyrene dual core, a new blue fluorescent material in the form of a polymer was developed. After introducing styrene at the end of the dual-core, a polymer blue emitting material was obtained through radical polymerization. In the case of the newly synthesized Poly 1-(4-vinylphenyl)-6-(10-(4-vinyl-phenyl)anthracen-9-yl)pyrene (S-AP-S), it not only emitted in the blue region of 443 nm in solution state, but also showed a high photoluminescence quantum yield (PLQY) of 79%. When Poly S-AP-S was applied as an emitter to solution process organic light-emitting diodes (OLEDs), current efficiency of 4.48 cd/A and external quantum efficiency (EQE) of 3.62% were realized. It also exhibited the deep-blue color coordinates of (0.157, 0.094) which satisfy with the mobile specification.
查看更多>>摘要：Different composition ratios poly(ethylene oxide) (PEO) and poly(vinylidene fluoride) (PVDF) blend films (PEO/PVDF) were investigated by employing a differential scanning calorimeter (DSC), ultraviolet-visible (UV-Vis) spectrophotometer, and radio frequency impedance analyzer (RF-IA). Crystalline phases of the PEO and PVDF in the blends, their melting temperatures and the degree of crystallinity were determined using the DSC thermograms. These structural parameters of the semicrystalline polymers explain a significant alteration in heterogeneous chains interaction with the composition variation of the constituents in the PEO/PVDF blends. The UV-Vis range absorbance spectra of these blend films were reported and analyzed for the determination of their optical energy band gap values. The decreased band gap values of the polymer blends as compared to that of the pristine polymers evidenced a considerable structural disordering of the polymers functional groups which cause the creation of the localized states that assisted the electronic transitions. The RF range dielectric permittivity of the PEO/PVDF blend films showed a gradual decrease with sweeping the frequencies from 1 MHz to 1 GHz, but it enhanced anomalously at the starting frequencies when the PVDF amount was relatively increased in the polymer blend. The alternating current (AC) electrical conductivity of these blends exhibited a linear variation with the change of frequency, and it notably altered at a fixed frequency when the polymer composition ratio in the blend films was varied. These experimental results of the PEO/PVDF blend films are highly creditable to emerging polymer-based flexible technologies of radio-electronic and optoelectronic devices.
Lee, Gyeong SeokOh, Jong GyuSuh, Eui HyunLee, Kyumin...
7页
查看更多>>摘要：A naphthalene diimide (NDI)-based small molecule with a thienothiophene linker (NDI-TT-NDI) was synthesized for use as a semiconductor layer in solution-processable n-type organic field-effect transistors (OFETs). The thienothiophene linker was introduced to the donor site between the two NDIs to impart planarity to the molecular backbone, which is favorable for inducing high crystallinity, and the morphological and crystal characteristics of the resulting film were analyzed. An additional annealing treatment applied to the NDT-TT-NDI films changed their orientation such that the molecular ordering and crystallinity of the film were significantly improved at a specific annealing temperature. The optimally annealed NDI-TT-NDI film exhibited a distinct edge-on molecular orientation with a narrow intermolecular pi-pi stacking distance, which is advantageous for lateral charge transport along the stacks. Consequently, an optimally annealed NDI-TT-NDI-based OFET exhibited electron mobilities of up to 0.032 cm(2)V(-1)s(-1) and an on/off ratio of 1.0 x 10(7).
查看更多>>摘要：The strengthening mechanism of graphene derivatives in the polymer composites is an interesting issue, which exhibits the excellent mechanical and tribological properties. In this case, the visual observation about the existing state of graphene nanosheets in the polymer composites is much more attractive to explain the intrinsic origin of graphene-strengthening mechanism. At present, the Raman imaging via nondestructive spectroscopic detection is an impactful tool to observe the carbonaceous materials in the graphene nanocomposites. Therefore, the Raman imaging will be applied in this work to detect the existing state of graphene oxide (GO) nanosheets in GO-hybrid polyurethane (PU)/epoxy (EP) interpenetrating polymer network (IPN) with an aim to make clear the GO-strengthening mechanism in GO-hybrid PU/EP IPN. The results obviously indicated the GO nanosheets are chemically bonded between polyurethane and epoxy, which is a key factor to mechanically strengthen GO-hybrid PU/EP IPN by transferring the polymeric stress to the GO nanosheets with high mechanical strength. Besides, the graphitization of GO nanosheets on the tribological surface of GO-hybrid PU/EP IPN is also evidently identified by Raman imaging, which provides a powerful evidence for the improvement of tribological performance in GO-hybrid PU/EP IPN. This work provided the powerful visual Raman imaging proofs for the mechanically/tribologically-strengthening mechanism of GO-hybrid PU/EP IPN, including the appearance of mechanical/tribological quasi-steady state.
Lee, HojoonKim, Min AhLee, Jung-SickLee, Chang-Moon...
9页
查看更多>>摘要：C-Phycocyanin (CPC) obtained from Spirulina platensis is a natural blue dye and is attracting attention due to its photodynamic activity, anti-inflammatory effect and anti-cancer properties. The aim of this study is to prepare the CPC-doxorubicin (CPC-DOX) nanoparticles and evaluate chemo-photodynamic therapeutic effects of the nanoparticles in a mouse model bearing CT26 colorectal cancer xenograft CPC-DOX conjugate prepared by amide coupling method was characterized by Fourier transform infrared spectroscopy. CPC-DOX conjugate was suspended in PBS buffer and sonicated for formation of self-assembled nanoparticles. The size distribution and morphology of CPC-DOX nanoparticles were analyzed by dynamic light scattering and transmission electron microscopy. Reactive oxygen species (ROS) generation from CPC-DOX nanoparticles was evaluated using 1,2-diphenylisobenzofuran (DPBF). To confirm chemo-photodynamic therapeutic effects of CPC-DOX nanoparticles, cell viability and cancer growth were investigated on CT26 cells and a CT26 xenograft mouse model. The CPC-DOX conjugate was successfully synthesized by amide coupling reaction. The conjugate formed self-assembled nanoparticles in aqueous solution. In generation of ROS using DPBF, CPC-DOX nanoparticles exhibited significantly higher DPBF photobleaching effect than CPC. CPC-DOX nanoparticles significantly decreased cell viability in CT26 cells by generation of singlet oxygen after 635 nm near-infrared (NIR) laser irradiation in vitro. CT26-bearing mice injected with CPC-DOX nanoparticles through the tail vein and irradiated with a 635 nm NIR laser showed the most cancer inhibition among all groups. In summary, nanoparticles formed from CPC-DOX conjugate have potential as novel chemo-photodynamic therapeutic agents for treating cancer.
NSTL
Polymer Soc Korea