Mechanical Behavior of PMMA/SiO 2 Multilayer Nanocomposites: Experiments and Molecular Dynamics Simulation Abstract Poly(methyl methacrylate) (PMMA)/nano-silica (nano-SiO2) nanocom-posite film with 256 layers containing different amounts of nano-SiO2 was manufactured by a new type of micro-nano multilayer co-extrusion technology. The structure, morphology and mechanical properties of PMMA/nano-SiO2 nanocomposite films were investigated through Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and tensile test Besides, molecular dynamics simulation ^J^ was adopted to study the dispersion and content effect on mechanical properties of PMMA/nano-SiO2 nanocomposite film. It is demonstrated that the tensile strength and the elongation at break of the composites improved with increasing nano-SiO2 content from 0 to 5 wt%, which was in good agreement with the Molecular Dynamics simulation. And the nanofiller dispersion in the multilayer nanocomposite film was better than that in the single-layer film with equivalent thickness under the effect of torsion lamination. Overall, the best performance was found for the nanocomposites of PMMA with nano-SiO2 content of 3.5 wt%.

Surface Modification of Polystyrene Beads with Sulfonamide Derivatives and Application to Water Softening System Abstract Removal of magnesium and calcium cations in water, called water softening, is an important procedure for industrial use. Although ion exchange resin and chelate resin are one of the most widely used materials for desalination, they have a drawback in regeneration, in which huge amount of salt or strong acidic/basic aqueous solution needs to be applied. In this research, sulfonamide-derived cation capturing system was suggested as an alternative. Sulfonamide derivatives usually show a sharp transition from charged to uncharged form at a specific pH, which alleviates the condition of regeneration. A variety of sulfonamide derivatives were introduced to polystyrene microbeads. 1.88±0.05 mmol/g of the sulfonamide-based ligand was introduced in maximal amount Cation chelating capacities of products were quantified through calcium ion capturing test, identifying several sulfonamides as promising cation capturing systems. Finally, their metal ion capturing capacities within specific pH ranges and regeneration properties in moderate acidic condition were verified. Among the surface-treated sulfonamide derivatives, glycine-conju-gated sulfonamide group, which had 0.90±0.01 mmol/g of ion capturing capacity and rapidly regenerated at pH 5.0, was found to be most appropriate for water softening application.

Direct Solvent-Free Modification of the Inner Wall of the Microchip for Rapid DNA Extraction with Enhanced Capturing Efficiency Abstract Nucleic acid (NA) extraction and purification are one of the crucial steps for NA-based molecular diagnosis. However, the currently developed methods are still suffering from many issues including long process time, complicated steps, requirement of trained personnel and potential inhibition caused by chaotropic agents and/ or residual reagents. Herein, a surface-modified NA extraction microchip (SNC) is newly fabricated by introducing poly(2-dimethylaminomethyl styrene) (pDMAMS) film engaged directly on the microchip surface via initiated chemical vapor deposition (iCVD) process. The positively charged SNC inner surface could directly capture the negatively charged NA efficiently and its performance is confirmed by fluorescence microscopy and X-ray photoelectron spectroscopy. The developed SNC exhibits the deoxyribonucleic acid (DNA) capture efficiency higher than 92% regardless of initial DNA concentration in range of 20 ng/µL to 0.01 ng/µL. With this versatile DNA-capturing surface, the genomic DNAs of Escherichia Coli O157:H7 (E. coli O157:H7) is successfully extracted directly from cell lysate in the SNC with higher than 90% of efficiency within 30 min. The extraction time can be reduced to at least of 10 min maintaining extraction efficiency higher than 50%. Furthermore, the genomic DNAs are directly extracted using the SNC without loss from various real samples including juice, milk and blood serum. The proposed SNC enables us to perform an one-step NA extraction for molecular diagnosis and has the potential to be integrated into a micro-total analysis in the fields of point-of-care diagnosis.

Fabrication of POX/PLGA Scaffold for the Potential Application of Tissue Engineering and Cell Transplantation Abstract Poly lactic-co-glycolic acid (PLGA), a synthetic polymer, belongs to the fabrication of poly(α-hydroxy acid) systems approved by the US Food and Drug Administration. PLGA has been widely used in clinical applications due to its excellent biocompatibility, controlled biodegradability, and convenient processability. However, their degradation products cause inflammation, their rate of hydrolysis is slow, and the release rate of the drug is delayed. Therefore, polyoxalate (POX), which is a biodegradable polymer, was used to overcome these problems. The amount of POX was gradually increased to reduce the toxicity of PLGA, and the degree of cell proliferation was confirmed. In this study, POX/PLGA film in different composition was prepared and they were characterized using scanning electron microscope (SEM). Fourier-transform infrared spectroscopy (FTIR), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), and real-time polymerase chain reaction (RT-PCR). Among the different combination studied, 50% POX/PLGA film showed better results for all the analyses performed compared with other scaffolds, when the National Institute of Health (NIH)/3T3 mouse embryo fibroblasts were cultured in vitro. We confirmed that 50% POX/PLGA film can be applied in different tissue engineering fields including bone tissue engineering and drug delivery applications.

Structure and Properties of Aromatic Polyimide Fibers Fabricated by a Novel “Reaction-Spinning” Method Abstract In this work, two sets of high performance polyimide (PI) fibers fabricated by a more environmentally-friendly and highly efficient “reaction-spinning” method were firstly reported. The relationship between the spinning rate, chemical structure and the imidization degree of the PI precursor fibers were investigated, and the results indicated a moderate low spinning speed and relatively flexible molecular chains are both favorable for the partial imidization reaction in the spinning process. 2D WAXD results demonstrate that the rigid PDA-based PI fibers possess a higher alignment of polymer chains along the fiber axis during the spinning compared to the flexible ODA-based PIs, resulting in enhanced mechanical properties, with the tensile strength of 1.2-2.8 GPa and modulus of 53.6-111.2 GPa, respectively. Meanwhile, ODA sets of PI fibers exhibit a higher loop strength and knot strength than the commercial Aramid and PBO fibers. The process used in this study has a significant potential for realizing industrial level production of high strength and high modulus PI fibers.

Effects of Hard Segment of Polyurethane with Disulfide Bonds on Shape Memory and Self-Healing Ability Abstract Self-healing polyurethane with disulfide bonds was synthesized using polycarbonate diol as a soft segment, and methylene diphenyl diisocyanate and 2-hydroxyethyl disulfide as a hard segment. Well-developed phase separation as the hard segments increased was confirmed by Fourier transform infrared spectra. The X-ray diffraction data showed that the crystallinity of the polycarbonate with a semicrystalline structure decreased as the HS increased, which affected the thermal, mechanical, and thermomechanical properties of the PU block copolymer. As the hard segments increased, the yield point on the strain-stress curve disappeared, and the mechanical properties (elongation at break and breaking stress) and the shape recovery rate of SHPU improved. The increase in the physical crosslinking between the hard segments contributed to improving shape recovery and mechanical properties. In particular, self-healing polyurethane with 30, and 35 wt% hard segments showed excellent self-healing ability at 80 C, while the self-healing ability for self-healing polyurethane with 40 wt% hard segments was decreased. The increase of the hard segment restricted the movement of the soft segment, thus the self-healing ability of SHPU with 40 wt% HS was decreased. It could be concluded that self-healing polyurethane synthesized using semicrystalline PC diol has a significant effect on shape recovery and self-healing efficiency due to the crosslinks between the hard segments.

Preparation of Degradable Polymeric Nanoparticles with Various Sizes and Surface Charges from Polycarbonate Block Copolymers Abstract ABA-type polycarbonate block copolymers with pendant vinyl ether and benzyl functionalities were synthesized by sequential ring-opening polymerization of functional cyclic carbonate monomers using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as an organobase catalyst. The vinyl ether moieties on the resulting block copolymers were readily conjugated with 3-mercaptopropionic acid, cysteamine hydrochloride, and L-cysteine hydrochloride monohydrate through thiol-ene “click” reactions, yielding anionic, cationic, and zwitterionic self-assembled nanoparticles, respectively, in corresponding buffers. The effect of pH on the size and surface charge of nanoparticles were examined.

Pretreatment of Microfibrillated Cellulose on Polylactide Composites Abstract Microfibrillated cellulose (MFC) in polymer has attracted increasing applications with the fully bioderived nanocomposites. Polymer composites from polylactide (PLA) and MFC were prepared using two different fiber preparations. Freezedried MFC was prepared and directly mixed with PLA in an internal mixer. The MFC premixed with PLA in an organic solvent was prepared, followed by an internal mixer for another composite. In addition, grafting cellulose on PLA using a compatibilizer was performed. In this research, composites containing 10 wt% MFC were used to investigate the influence of processing and compatibilizer on the mechanical and thermal properties. The processing procedure had a great influence on the mechanical and physical properties. The tensile strength was increased with filler loading and showed different values depending on the premixing step prior to processing. The storage modulus and loss tangent confirmed that the compatibilizer acted as the role of a bridge between filler and matrix, enhancing the mechanical properties. This experiment was conducted to compare the effect of pretreatment on the change of mechanical and thermal properties by using freeze-dried cellulose and cellulose suspension substituted with an organic solvent.

Cationic Oligopeptide-Functionalized Mitochondria Targeting Sequence Show Mitochondria Targeting and Anticancer Activity Abstract Mitochondrial drug delivery systems require development of highly selective mitochondria-targeting carriers. In this study, we report that mitochondria targeting sequence (MTS)-hybrid cationic oligopeptide, MTS-H3R9, shows the dual role of a mitochondria targeting vector along with anticancer effect for cancer therapy. In cytotoxicity assays, MTS-H3R9 was shown to be more effective than MTS. MTS-H3R9 showed significant cell penetration and internalization activity compared to that of MTS along with more efficient escape from lysosome to the cytosol. We showed efficient targeting of MTS-H3R9 to mitochondria in HeLa cell line. Furthermore, we exhibited anticancer agent properties that mitochondrial-accumulated MTS-H3R9 caused cell death by reactive oxygen species generation and loss of mitochondrial membrane potential. MTS-H3R9 exhibited dramatically increased anticancer activity in 3D spheroids as well as in a 2D culture model. We demonstrated that MTS-H3R9 provides dual potentials both as a vehicle for targeted delivery and as a cancer treatment agent for therapeutic applications.

Improving Mechanical Properties and Thermal Conductivity of Styrene-Butadiene Rubber via Enhancing Interfacial Interaction Between Rubber and Graphene Oxide/Carbon Nanotubes Hybrid Abstract To fully utilize the fascinating comprehensive properties of graphene oxide (GO) and carbon nanotubes (CNTs), GO was used to promote the dispersion of carboxylated multi-walled carbon nanotubes (CC) in rubber matrix. Additionally, carboxylated acrylonitrile butadiene rubber (xNBR) was used to enhance the interfacial interaction between the styrene-butadiene rubber (SBR) and the GO/CC hybrid fillers for the formation of hydrogen bonds between the oxygenated functional groups of GO/CC hybrid fillers and the carboxyl groups of xNBR. Moreover, the interfacial interaction was investigated by Fourier transform infrared spectroscopy and further proved by differential scanning calorimetry. As a result, the mechanical property and thermal conductivity of SBR composites were improved significantly compared with the neat SBR vulcanizate, which were much higher than those of the SBR composites without xNBR. In contrast to adding GO/CNTs directly to the rubber matrix, enhancing the interfacial interaction between GO/CC hybrid fillers and rubber matrix as demonstrated herein is a valuable strategy to prepare rubber composites with remarkable comprehensive properties.