最新刊期
卷 ， 期 2 ， 2015
- 摘要：Nanoparticles (NPs) that are capable to convert near-infrared (NIR) irradiation into thermal energy have been demonstrated as the robust media for tumour curing. In this scenario, the photothermal performance of NPs greatly depends on their size, morphology, surface property, as well as the self-assembly architectures. Therefore, the practical applications of photothermal NPs in cancer therapy are determined by the technique progresses of nano-fabrications and multi-functional integration. In this scenario, the photothermal performance of NPs greatly depends on their size, morphology, surface property, as well as the self-assembly architectures. Therefore, the practical applications of photothermal NPs in cancer therapy are determined by the technique progresses of nano-fabrications and multi-functional integration. In this article, we summary a series of methods to enhance NP photothermal performance, such as control preparation of nanostructures, directing NPs self-assembly into specific architectures, and further photothermal polymer coating. The combination of these issues ensures the improvement of photothermal performance, colloidal and physiological stability, as well as biocompatibility.关键词：Photothermal therapy;Nanoplatform;Self-assembly;Nanoparticle;Composites
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发布时间：2021-03-19
Feature Articles
- 摘要：The two-dimensional network structure of graphdiyne and graphyne has high degrees of -conjunction, wide spacing, excellent chemical stability and semiconductor properties. The special electronic structure and pore structure of graphyne endow it with potentially important applications and market prospects in information technology, electronics, energy, catalysis and optoelectronics. Since the successful synthesis of graphdiyne in 2010, these materials are attracting much attention from attracting scientists from chemistry, physics, materials, electronics, microelectronics and semiconductors to explore their semiconductor, microelectronics, optics, energy storage, catalysis and mechanical properties. This paper summarizes the progress of two-dimensional polymer graphdiyne and graphyne, with a focus on theoretical predictions of the potential properties of graphdiynes and graphynes, as well as the synthesis of graphdiynes and its applications in electronics, photovoltaics, energy storage and catalysis.关键词：Two dimensional polymer;Carbon allotrope;Graphdiyne;Graphyne
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发布时间：2021-03-19
Reviews
- 摘要：The composites based on the EVA/EVM thermoplastic vulcanizates and organoclay have been fabricated by two different strategies:(1) One-step fabrication by directly dynamically vulcanizing the EVA/EVM blends with organoclay using a peroxide; (2) Two-step fabrication by first preparing the TPV by dynamic vulcanization followed by melt mixing with organoclay. The structure and properties of the composites have been investigated. Organoclay was selectively located in the crosslinked EVM phase for all the samples by the two strategies. However, it was found that the composites fabricated by the two-step strategy have much smaller phase size and the organocaly shows much higher exfoliation efficiency than those fabricated by one-step strategy. It was further found that the composites fabricated by the two-step strategy exhibit much better physical properties than those by one-step strategy. The tensile strength and elongation at break are 15. 5 MPa and 856% for the two-step fabricated sample with 5% organoclay, respectively, as compared with 9. 1 MPa and 423% for the one-step fabricated sample. Moreover, the limit oxygen index (LOI) of the two-step fabricated samples is also higher than that of the one-step fabricated sample.关键词：Dynamic vulcanization;Organo-montmorillonite;Thermoplastic vulcanizates;Composites
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发布时间：2021-03-19 - 摘要：The bio-catalysed cleavage of ester bonds in poly(butylene succinate-co-hexane succinate) (PBSH) was studied with the aim to gain more underlying information about the degradation rules and differences in chloroform and tetrahydrofuran. Among various hydrolytic enzymes the lipase from Pseudomonas cepacia (PC) was chosen for the studies. The rules of enzymatic degradation were investigated by molecular weight variation and MALDI-TOF-MS analysis of the degradation products. Additionally, solvent effect and mechanism of the combination between substrate and enzyme were studied with molecular dynamics (MD) simulations and molecular docking. The results suggested that PBSH showed an obvious degradation both in chloroform and tetrahydrofuran. Particularly higher activity of PC lipase and greater degradation of PBSH were observed in chloroform. Molecular dynamics simulations data showed that root mean square fluctuation (RMSF) of the whole residues of PC lipase in tetrahydrofuran was greater than that in chloroform. In tetrahydrofuran, the solvent molecules could reach the active site and interact intensively with the active residues Ser87. This interaction destroyed the hydrogen bonding between Ser87 and His286. According to the results of molecular docking, the substrate containing hexane succinate (HS) docked more stably in the enzyme active site than butylene succinate (BS).关键词：Enzymatic degradation;Degradation products;PBSH;Molecular dynamics;molecular docking
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发布时间：2021-03-19 - 摘要：A scaling theory is presented to analyze the effects of the added multivalent counterions on properties of cylindrical polyelectrolyte brushes. The theory demonstrates four possible regimes for the behavior of the brushes, while there are only two regimes for the quenched brushes and three for the annealed brushes with monovalent counterions. In the first regime, the salt concentration is too low to have effects on the brushes. In the next regime, the brush thickness decreases with the increase of the concentration of the added salt. The thickness of quenched polyelectrolyte brushes is independent of the salt concentration in the third regime, while the annealed polyelectrolyte brushes swell with the increase of the salt concentration in the regime and depend on the counterion valence. In the last regime, the brush with added multivalent counterions behaves as the brush with monovalent salt does. These regimes are consequences of the balance of the entropic elasticity of the grafted chains and the osmotic pressure of the mobile ions. The regimes are connected with the exchange of the monovalent and the multivalent counterions in the brush. The boundaries between the neighbour regimes are also discussed. The new findings wait for experiment and computer simulation testing.关键词：Cylindrical polyelectrolyte brush;Scaling theory;Mean field theory;Polyelectrolyte
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发布时间：2021-03-19 - 摘要：High softening point polycarbosilane (HPCS) was synthesized via hydrosilylation reaction by using low softening point polycarbosilane (LPCS) with an appropriate molecular weight distribution and tetramethyldivinyldisilazane (TMDS) as starting materials. The progress and characteristics of the hydrosilylation reaction were investigated, and the impact of mass ratio of TMDS on the properties of the production, as well as the relationship between structure and spinnability of HPCS were also discussed. The results show that the hydrosilylation reaction of LPCS and TMDS was in a stepwise manner. The low molecular weight part of LPCS reacted with one vinyl of TMDS to form a hanging structure in the initial stage of the reaction. Subsequently, another LPCS molecule coupled with the product of the first step to form a SiNSi bridged structure until the hydrosilylation reaction was completed. The increase of molecular weight and softening-point of HPCS can be adjusted by controlling the content of bridged structure in HPCS, which can be tuned by changing the mass ratio of TMDS. HPCS (244~278 ℃) with a number average molecular weight of 2. 5103 and good spinnability was successful synthesized by optimizing the mass ratio of TMDS and LPCS at 0. 08 which was suitable for preparing high-performance continuous silicon carbide fibers.关键词：High softening point;Polycarbosilane;Bridged method;Spinnability
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发布时间：2021-03-19 - 摘要：The MoS2 nanosheets suspensions were prepared based on liquid exfoliation method. The suspensions are characterized by absorbance and photoluminescence (PL) spectroscopy. The results show the PL signal from suspensions is enhanced evidently. Meanwhile, the optimized processing conditions, such as increasing of ultrasonic time, decreasing of centrifugal rotational speed, using large-size bulk MoS2 and adding ball-milling process, could enhance the absorbance of the suspensions. Using micro-area PL testing can obtain the PL signal from single MoS2 nanosheet, and it's PL main peak is located at 652 nm, which corresponds to a band gap of 1. 9 eV. When the single MoS2 nanosheet is annealed, its PL signal is enhanced. The morphology of MoS2 nansosheets is characterized by SEM and AFM, the results show the most MoS2 nansosheets have a lateral size of several hundred nanometers and a thickness of several nanometers. Besides, MoS2 nansosheets reinforced epoxy composites were prepared by mixing MoS2 nansosheets suspension and E51 epoxy. The composites are characterized by PL and tensile testing. And the results show the PL signal from composites is enhanced as well. While the composites are annealed, the PL signal shows obvious shift which could be ascribed to residual thermal stress in the composites. Meanwhile, the toughness of the composites is also improved.关键词：Liquid exfoliation;MoS2 nansosheets;Photoluminescence (PL);Composites;Annealing;Residual thermal stresses
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发布时间：2021-03-19 - 摘要：The weak and strong interaction between carbon black (CB) and polymer was separated by means of solution-soaking method and high-speed centrifugation method for CB filled BR compounds. The relationship between multi-interaction of CB filled BR composites and CB concentration was investigated and a multi-interaction evolution model between CB and polymer was proposed with increasing of CB concentration, based on the relationship between different bound rubber contents and relative storage modulus. The results showed that the glass transition temperature (Tg) and crystallization melting peak, which existed in CB gelⅠ, disappeared absolutely in CB gel II. It meant that the glass transition temperature and crystallization behavior, which were detected in CB gelⅠ, were attributed to the weak interaction between CB and polymer. The features of samples and measurement method should be noticed when glass transition temperature was used to indicate filler-polymer interaction. The concentration of BdR II (bound rubber II) increased linearly with increasing of CB concentration, when CB concentration was not more than 50 phr, and BdR I concentration was affected significantly by CB concentration. The multi-interaction of CB filled BR composites could be described by means of an overlapping model. There were BdR III layer overlap, BdR II layer overlapping with BdR III layer, and BdR II layer overlap, when the CB concentration was 25~35 phr, 50~55 phr and 70~80 phr, respectively.关键词：Bound rubber;Multi-interaction;Payne effect;Filler-polymer interaction;Overlapping layer
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发布时间：2021-03-19 - 摘要：Nanosilica particles (SiO2) were modified with 3-(trimethoxysilyl)propyl methacrylate (MPS) and octyltrimethoxysilane (OTMS), respectively. The density of anchored silanes could be conveniently adjusted through addition of various amounts of silane. The saturated densities for both silanes are about 3 mol (m2 SiO2)-1. The bulk free-radical polymerization of methyl methacrylate (MMA) was carried out in the presence of SiO2 with different surface modifications to prepare SiO2/poly(methyl methacrylate) (SiO2/PMMA) composites. Influences of the type of anchored silanes and the content of SiO2 on the polymerization rate, molecular weight of PMMA, and hardness of the SiO2/PMMA composites were investigated. The polymerization rate is obviously retarded by addition of SiO2 nanoparticles. The order of retardation effect on polymerization is unmodified SiO2 MPS-modified SiO2 OTMS-modified SiO2. Moreover, the retardation effect increases with the increase of the amount of SiO2 nanoparticles. In addition, the molecular weight of PMMA and the hardness of SiO2/PMMA composites are clearly reduced with the addition of SiO2 nanoparticles. We assume that the silanol groups on the SiO2 surface play a role of chain transfer agent to reduce the molecular weight of PMMA and subsequently to reduce the hardness of SiO2/PMMA composites. In addition, the produced SiO may be not as active as the primary or propagating radicals, and therefore retard the polymerization rate. For the MPS-modified SiO2. It is in addition to the chain transfer effect of silanols groups, the grafting of propagating radicals to MPS units will confine the radicals on the surface of SiO2, which may also decrease the activity of radicals and subsequently retard the polymerization rate and decrease the molecular weight of PMMA. These assumptions are confirmed by the fact that the retardation effect on the polymerization rate is alleviated and the molecular weight of PMMA is increased by using OTMS-modified SiO2 to replace unmodified or MPS-modified SiO2. It is because on one hand, the active silanol groups are consumed by OTMS, leading to the suppression of chain transfer reaction to SiO2, and on the other hand, the use of OTMS can avoid the grafting reaction to SiO2 nanoparticles. This study aims to understand how the surface properties of inorganic nanoparticles may influence the free-radical polymerization of acrylate monomer and the corresponding products.关键词：Nanosilica;Active group;Molecular weight;Inhibition and retardation effects
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发布时间：2021-03-19 - 摘要：Hybrid nanofiber membranes of poly(ethylene terephthalate) and chitosan (PET/CTS) were prepared by electrospinning technology. Moreover, adsorbing a layer of nanosilver on the fiber membrane was used to further increase the antibacterial properties of fiber membranes. The surface morphology of membranes with the different ratios of PET/CTS was characterized by scanning electron microscopy (SEM), and the results showed that 12. 5% is the best ratio and the average diameter of nanofiber was 405 nm. Besides, the influences of membrane thinkness on mechanical properties, air permeability and air filtration performance were studied. Results reveal that when the spinning time is 7 h, the fiber membrane has good performance, and its elastic modulus is 48. 15 MPa, elongation at break is 183. 30%, tensile stress is 2. 11 MPa, tensile strength is 2. 49 MPa, the tensile yield stress is 1. 23 MPa, the maximum force is 1. 38 N, the air resistance value is 3. 99 kPa S/m, the filtration efficiency is 99. 55% and the pressure drop is 621. 32 Pa, respectively. In addition, the result of crosslinking experiment indicates that the best proportion is GA(vol%)=3. 5%. Finally, UV visible spectroscopy (UV) and transmission electron microscopy (TEM) characterization reveals that the size of nanosilver is above 10 nm and the antimicrobial test shows that the antibacterial ratio for s. a. and E. coli. can reach 99. 97% and 99. 99%, respectively.关键词：Electrospinning;Air filter;PET/CTS;Antibacterium;Nanofiber membrane
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发布时间：2021-03-19 - 摘要：To obtain the shell cross-linked PLGA-NPs (PCV-NPs), PLGA nanoparticles (PNPs) were prepared by emulsification technique first. Subsequently, chitosan was coated on the surface of the PLGA-NPs via the electrostatic interaction. Finally, vanillin, a non-toxic chemical cross-linker, was chosen to react with the chitosan to form Schiff base on the surface of nanoparticles. Size and zeta potential of PCV-NPs detected by Malvern Zetasizer Nano ZS90 were in the range of (277. 60 38. 01) nm and (21. 60 4. 51) mV, respectively. Besides, SEM images show PCV-NPs have smooth and spherical morphology. Infrared spectroscopy was used to detect the chemical structure of all the NPs, and the characteristic vibrating peak of the Schiff base at 1640 cm-1 emerged on the spectral line of PCV-NPs. PCV-NPs performed excellent stability within 24 h incubation in the serum containing medium. The cellular uptake study was performed using hydrophobic fluorescein coumarin 6, the results indicated coumarin 6-loaded PCV-NPs possessed better transmembrane transport capacity compared with P-NPs. And the cytotoxicity studies demonstrated that there was no obvious cytotoxicity of blank PCV-NPs. Furthermore, docetaxel, a model drug, was encapsulated into PCV-NPs with high drug loading (7. 48%) and entrapment efficiency (34. 98%). In addition, the DTX cumulative release of DTX-loaded PCV-NPs was 58. 66% after 90 h of incubation at pH 5. 0. In comparison, the drug release was reduced to 50. 63% at pH 7. 4. DTX-loaded PCV-NPs showed efficient cell killing ability after 48 h incubation with A549 cells, the IC50 value of which was 0. 0009 g/mL.关键词：PLGA nanoparticles;Chitosan;Vanillin;Shell crosslinked;pH-responsible
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发布时间：2021-03-19 - 摘要：To obtain side-chain ferrocene-containing multifunctional polymers 2-acryloyloxyethyl ferrocenecarboxylate(AEFC) was synthesized and characterized via esterification reaction in this work. Ferrocenecarboxylic acid (FCA), 2-hydroxyethylacrylate (HEA), N, N'-dicyclohexylcarbodiimide(DCC) and 4-di(methylamino)-pyridine (DMAP) were used as reagent, dehydrating agent and catalyst, respectively. Then poly(2-acryloyloxyethyl ferrocenecarboxylate) (PAEFC) was synthesized and characterized by ATRP in toluene at 100 ℃, wherein, AEFC, copper(I) bromide (CuBr), 2, 2'-bipyridine (bpy) and three kinds of bromoalkane were used as monomer, catalyst, ligand, and initiator, respectively. Three kinds of different initiators are ethyl bromoacetate (EBrA), methyl 2-bromopropionate (2-MBP) and ethyl 2-bromoisobutyrate (EBiB) respectively. Meanwhile, the influences of these different initiators on the polymerization kinetics were compared. These studies indicated that the procedure of polymerization of monomers doesn't follow a living/controlled manner with EBrA as initiator, while, the procedure of polymerization follows a living/controlled manner with 2-MBP and EBiB as initiator, respectively, and the controlability of EBiB is better than that of 2-MBP. In addition, the effects of EBiB and CuBr dosages on the process of polymerization were studied, and the suggested molar ratios AEFC/EBiB and AEFC/CuBr were 100/1 and 100/2, respectively. Thermal properties of the polymer demonstrated that it has lower melting point 158. 2 ℃, thermal decomposition enthalpy of 9541 J/g and higher decomposition temperature of 200~460 ℃.
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发布时间：2021-03-19
Research Article
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