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1.
Alvianto Wirasaputra Lijun Zheng Shumei Liu Yanchao Yuan Jianqing Zhao 《大分子材料与工程》2016,301(5):614-624
The flame retardancy and mechanical properties of polyamide‐6 (PA6)/aluminum diethylphosphinate (AlPi) composite are greatly improved by the addition of novelly synthesized phosphorus flame retardant‐based diepoxide (DEP) during extrusion. The PA6/AlPi/DEP composite passes V‐0 rating of UL94 test with limiting oxygen index (LOI) of 32.6% at 13 wt% AlPi and 1 wt% DEP, as revealed by the results of flammability. The synergistic flame retardation mechanism offered by the two additives (AlPi and DEP) is studied in terms of in‐depth characterization of the charred residue and evolved gas. The deteriorated mechanical strength of PA6 due to existence of AlPi is compensated by the simultaneous chain extension effect of DEP. Accordingly, the flexural and impact strengths of PA6/AlPi/DEP composite are even superior to those of neat PA6.
2.
Polydopamine‐Assisted Electrochemical Fabrication of Polypyrrole Nanofibers on Bone Implants to Improve Bioactivity 下载免费PDF全文
Zhengao Wang Lei Zhou Peng Yu Yan Liu Junqi Chen Jingwen Liao Weiping Li Wei Chen Wenhao Zhou Xin Yi Kongyou Ouyang Zhengnan Zhou Guoxin Tan Chengyun Ning 《大分子材料与工程》2016,301(11):1288-1294
Dopamine is a molecule that facilitates biomineralization, and it is used to prepare electropolymerization‐induced polydopamine (PDA). For the first time, dopamine is used for template‐free electrochemical polymerization to form biocompatible polypyrrole (PPy) nanofiber coatings on bone implants. Dopamine monomers are electropolymerized to PDA chains affixed to biomedical titanium after the nanomicelles are tuned to self‐assemble by triggering the potential, resulting in nanofiber formation. Dopamine serves as a dopant to induce the formation of conductive PPy nanofibers and as a promoter to accelerate biomineralization, cell proliferation, and adhesion.
3.
Polymer Self‐Etching for Superhydrophobicity through a Green Hot‐Pressing‐Exfoliation Process: Low and High Adhesion 下载免费PDF全文
A green polymer self‐etching strategy for fabricating superhydrophobic surfaces exhibiting low and high adhesion is proposed by using hot‐pressing and exfoliation on a pair of low density polyethylene (LDPE) films. It is demonstrated that the hot‐pressing temperature has significant influence on the surface morphology of LDPE. Effective hot‐pressing temperature for low‐adhesive superhydrophobicity ranges from 109 to 161 °C. Bird's‐nest like micro‐/nanostructures are observed in the unzipped LDPE surfaces compressed at 109 °C, which shows excellent water repellency. LDPE surface compressed at 108 °C demonstrates superhydrophobicity with high adhesion, i.e., a water droplet cannot roll off even when the surface is turned upside down. Furthermore, superhydrophobic vessels are processed and applied to transport water and microdroplets of water losslessly.
4.
Nanofiber‐Based Hydrocolloid from Colloid Electrospinning Toward Next Generation Wound Dressing 下载免费PDF全文
Nanofiber‐based hydrocolloid scaffold is prepared by colloid electrospinning of thermoplastic polyurethane (TPU)/sodium carboxymethyl cellulose (S.CMC) in tetrahydrofuran (THF)/dimethylformamide (DMF). The most suitable process of electrospinning for successful formation of fibers is investigated by controlling the concentration of polymeric solution and co‐solvent ratio. In order to accomplish high wettability, the amount of colloid (S.CMC) and the co‐solvent ratio (THF/DMF), which affects the morphology of fibers, are adjusted. Finally, the open wound healing effect is confirmed using nanofiber‐hydrocolloid from in vivo animal studies. A detailed study of the wound healing process is also demonstrated for the first time.
5.
Impressive Rate Raise of the Hydrosilation Reaction Through UV‐Activation: Energy and Time Saving 下载免费PDF全文
Silicone materials are widely used in many fields such as electrical or food industries and their consumption is constantly growing. They are generally cured by vulcanization reaction for long time at high temperatures which requires high energy consumption. The possibility to achieve the polymerization of silicone rubbers by UV‐activation promotes the reduction of both time and temperature leading to an impressive energy saving. Indeed, this process is more than 30 times faster than the thermal one. Moreover, the properties of the two resulting materials are comparable, indicating that the low time of UV‐activated hydrosilation reaction is suitable for the formation of crosslinked silicone polymers.
6.
Fabrication and Characterization of Electrospun Dopants/PS Composite Fibers with Porous and Hollow‐Porous Structures 下载免费PDF全文
Lidong Tian Junwei Gu Xingfeng Lei Zhaoyuan Lv Mingtao Qiao Changjie Yin Qiuyu Zhang 《大分子材料与工程》2016,301(5):625-635
Three different dopants are used to fabricate electrospun dopants/polystyrene (dopants/PS) composite fibers from PS solution and PS sol. The relative humidity and the influence of the dopants on the morphologies, diameter, porous structures, and dopant distribution of electrospun PS fibers are investigated. Compared to those obtained from PS solution, electrospun dopants/PS composite fibers from PS sol with hollow‐porous and multichannel hollow‐porous structures present significant advantages due to the multi‐stage degree of interfacial structure and diversity of the internal environment. In comparison to coaxial electrospun PS fibers, the electrospun dopants/PS composite fibers from PS sol obtained in one step have an improved yield and a simplified technological process simultaneously, leading to significant competitiveness in fields such as catalysis, fluidics gas storage, and sensing.
7.
Observation of Confinement‐Induced Self‐Poling Effects in Ferroelectric Polymer Nanowires Grown by Template Wetting 下载免费PDF全文
Ferroelectric polymer nanowires grown using a template‐wetting method are shown to achieve an orientated “self‐poled” structure resulting from the confined growth process. Self‐poling is highly desirable as it negates the need for high electric fields, mechanical stretching, and/or high temperatures typically associated with poling treatments in ferroelectric polymers, as required for piezoelectric and/or pyroelectric applications. Here, differential scanning calorimetry, infrared spectroscopy, and dielectric permittivity measurements have been presented on as‐fabricated template‐grown polyvinylidene fluoride‐trifluoroethylene nanowires, and quantitatively compared with spin‐cast films of the same composition that have been electrically poled, both before and after subsequent depoling temperature treatment. The measurements reveal remarkably similar trends between the physical properties of the as‐grown nanowires and the electrically poled film samples, providing insight into the material structure of the “self‐poled” nanowires. In addition, piezoresponse force microscopy data are presented that allow for unambiguous identification of self‐poling in ferroelectric polymer nanostructures. Our results indicate the suitability of the template‐wetting approach in fabricating nanowires that can be used directly for piezoelectric/pyroelectric applications, without the need for post‐deposition poling/processing.
8.
Synthesis and Properties of GO‐Doped Porous Hydrogel Nanocomposites with Semi‐Interpenetrating Network Structure 下载免费PDF全文
Superabsorbent hydrogel nanocomposites (SHN) with semi‐interpenetrating polymer network (semi‐IPN) are synthesized by the polymerization of acrylamide monomer in a polyethylene glycol aqueous solution in the presence of the octadecylamine (ODA)‐modified graphene oxide (GO‐ODA) nanosheets. The hydrogel composites are characterized by Fourier transform infrared spectroscopy, thermal gravity analysis, and scanning electron microscopy. The water absorbency of the resulting SHN in distilled water and saline solutions are measured. The results show that doping GO‐ODA nanosheets into hydrogel semi‐IPN would enhance both their salt resistance and water retention. Using a simple freezing‐dry method, porous SHN with macroscopically interconnected pores is prepared, which exhibits excellent separation ability for removal of trace water from oils. Based on their better water absorbency, salt resistance, and excellent oil/water separation ability, the resulting SHN has great potentials in a wide range of applications, for example, oil dehydration, absorption, and separation.
9.
Alvianto Wirasaputra Xiaohao Yao Yaming Zhu Shumei Liu Yanchao Yuan Jianqing Zhao Yi Fu 《大分子材料与工程》2016,301(8):982-991
A 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO)‐triazine based anhydride (2,4,6‐tris‐(DOPO‐methylformatephthalic anhydride‐phenoxy)‐1,3,5‐triazine (TDA)) is synthesized and used as a halogen‐free flame retardant co‐curing agent for diglycidyl ether of bisphenol A/methylhexahydrophthalic anhydride (DGEBA/MHHPA) system. The conjugation of anhydride group is increased by the utilization of TDA, leading to the reduction in the curing activation energy. The cured epoxy resin passes V‐0 rating of UL 94 test with the limiting oxygen index of 32.7 vol% when the phosphorus content is only 1.5 wt%. The flame‐retarding action of triazine ring and DOPO moiety is investigated by the residue analysis and the characterization of pyrolysis gas. Due to the presence of bulky aromatic subunits in the molecular structure of TDA, the flame‐retarded epoxy resins maintain the high glass transition temperature of DGEBA/MHHPA. Besides, the moisture absorption is diminished following the usage of TDA.
10.
Enhancement of Mechanical and Self‐Healing Performance in Multiwall Carbon Nanotube/Rubber Composites via Diels–Alder Bonding 下载免费PDF全文
Mechanically robust and self‐healing rubbers are highly desired to satisfy the increasing demand of high‐performance smart tires and related materials. Herein, a self‐healing rubber nanocomposite with enhanced mechanical and self‐healing performance based on Diels–Alder chemistry has been investigated. The furfuryl grafted styrene‐butadiene rubber and furfuryl terminated MWCNT (MWCNT‐FA) are reacted with bifunctional maleimide to form a covalently bonded and reversibly cross‐linked rubber composite. Obvious reinforcing effect is obtained at high cross‐linking density. Over 200–300% increase in the Young's modulus and toughness can be achieved in the rubber nanocomposites with 5 wt% MWCNT‐FA. Meanwhile, the healing efficiency increased with MWCNT‐FA content. MWCNT‐FA plays dual roles of effective reinforcer and a kind of healant.
11.
Fabrication of Robust Hydrophobic and Super‐Hydrophobic Polymer Films with Onefold or Dual Inverse Opal Structures 下载免费PDF全文
Hydrophobic and super‐hydrophobic materials have many important applications, but most of the artificially hydrophobic and super‐hydrophobic surfaces suffer from poor durability. Herein, a facile method is reported to fabricate robust hydrophobic and super‐hydrophobic polymer films through backfilling the silica colloidal crystal templates with the mixture of fluoropolymer, thermoset hydroxyl acrylate resins, and curing agent. After removal of the template, 3D ordered porous structures are obtained. The obtained polymer films have not only excellent hydrophobic or super‐hydrophobic properties but also good stability against temperatures, acids, and alkalis. Dual ordered porous structure can obviously enhance the hydrophobicity of polymer films compared to unitary one.
12.
Grafting of a Stimuli Responsive Polymer on Nanolayered Coextruded PS/PCL Films by Surface Initiated Polymerization 下载免费PDF全文
Katrina D. Pangilinan Al Christopher C. de Leon Joey Dacula Mangadlao Eric Baer Rigoberto C. Advincula 《大分子材料与工程》2016,301(7):870-875
A simple method of preparing stimuli‐responsive polystyrene (PS)/polycaprolactone (PCL) nanolayered films with by growing poly(N‐isopropylacrylamide) (PNIPAM) brush on the surface by surface‐initiated polymerization is reported. Atom transfer radical polymerization (ATRP) initiator with a benzophenone moiety is attached onto the surface by UV irradiation. After ATRP polymerization, PNIPAM brush films with varying thicknesses are produced. X‐ray photoelectron spectroscopy (XPS) confirms the successful deposition of initiator and grafting of the polymer. Moreover, the behavior of the brush film as a function of temperature is demonstrated by contact angle experiments. Photopatterning is also achieved by using a photomask and is confirmed by Fourier Transform Infrared (FTIR) imaging.
13.
Effects of Surface Deactivation of Carbon Black on Thermomechanical Sensitivity of Filler Networks in Rubber Compounds 下载免费PDF全文
The strain and thermal dependence of the dynamic mechanical properties of carbon black filler networks underpin the performance of many rubber components. These effects are examined by varying the surface energetics of carbon black. This has a profound influence on the level of flocculation of the carbon black network in the final crosslinked compounds. Filler networks comprised of thermally deactivated carbon blacks are significantly more strain‐sensitive – shifting the onset of the Payne effect to smaller dynamic strains. Using free vibration equipment to precisely probe the thermal sensitivity of the linear viscoelastic properties of the filled compounds, it is shown that carbon black deactivation results in carbon black networks which are more thermally sensitive than corresponding unmodified carbon black networks. Increased thermal dependence of the dynamic moduli results in the appearance of a secondary increase in tan δ as a function of increasing temperature well above the rubber Tg – which is not correlated with any thermal transitions in calorimetric experiments. Such effects are prevalent in the relevant literature for various rubber–filler combinations but their physical origins are often misinterpreted or unexplained. A rationalization of these effects based on the dynamics of the filler network is presented.
14.
Utilization of Electrospun Polystyrene Membranes as a Preliminary Step for Rapid Diagnosis 下载免费PDF全文
Recent advances in clinical practice drive deoxyribonucleic acid (DNA) as an important class of biomarker. Monitoring the change in their concentration suggests the initiation and/or progression of various disorders. However, low quantity of DNA biomarkers in body fluids requires a delicate isolation methodology that provides efficient separation and easy handling. This study describes a newer‐generation separation technology relying on electrospun fibers of sub‐micrometer diameter of a commodity polymer for DNA biomarkers in simulative serum. Fibrous polystyrene membranes are prepared by electrospinning and they are subjected to post‐modification with Au. The composite membranes may provide a convenient environment for the removal of bovine serum albumin (BSA) from BSA and DNA mixtures. The eluent can be used as an efficient tool for detection of DNA biomarkers associated with diagnosis of numerous life‐threatening diseases.
15.
Making Nonwoven Fibrous Poly(ε‐caprolactone) Constructs for Antimicrobial and Tissue Engineering Applications by Pressurized Melt Gyration 下载免费PDF全文
Zewen Xu Sunthar Mahalingam Pooja Basnett Bahijja Raimi‐Abraham Ipsita Roy Duncan Craig Mohan Edirisinghe 《大分子材料与工程》2016,301(8):922-934
A pressurized melt gyration process has been used for the first time to generate poly(ε‐caprolactone) (PCL) fibers. Gyration speed, working pressure, and melt temperature are varied and these parameters influence the fiber diameter and the temperature enabled changing the surface morphology of the fibers. Two types of nonwoven PCL fiber constructs are prepared. First, Ag‐doped PCL is studied for antibacterial activity using Gram‐negative Escherichia coli and Pseudomonas aeruginosa microorganisms. The melt temperature used to make these constructs significantly influences antibacterial activity. Neat PCL nonwoven scaffolds are also prepared and their potential for application in muscular tissue engineering is studied with myoblast cells. Results show significant cell attachment, growth, and proliferation of cells on the scaffolds.
16.
Yamin Pan Xianhu Liu Suyu Shi Chuntai Liu Kun Dai Rui Yin Dirk W. Schubert Guoqiang Zheng Changyu Shen 《大分子材料与工程》2016,301(12):1468-1472
The mechanical properties and microstructure of injection molded isotactic polypropylene parts with high orientation before and after annealing are analyzed. The mechanical properties of the annealed samples are improved effectively. Through thorough analysis of various structural characterizations, a microstructural model based on the fact that the total length of long period kept constant to analyze the variation of mechanical properties is proposed. It is suggested that the increase of overall crystallinity, the recombination of crystalline phase, and the increase of amorphous phase, respectively, are beneficial for the improvements of the strength, stiffness, and toughness of annealed samples.
17.
Blends of polyamide 12 and small amounts (0.15–1 wt%) of the excimer‐forming fluorescent dye 1,4‐bis(α‐cyano‐4‐octadecyloxystyryl)‐2,5‐dimethoxybenzene (C18‐RG) are produced by melt‐processing. While green monomer fluorescence from well‐individualized chromophores is observed at low dye concentration (0.15%), higher dye concentrations lead to aggregation of the dye so that the emission characteristics are dominated by red excimer fluorescence. Upon mechanical deformation of samples with appropriately selected dye content (0.25 wt%), a pronounced mechanochromic effect can be observed, which manifests itself through a mechanically induced transformation from excimer‐dominated to monomer‐rich emission. The monomer to excimer emission ratio IM/IE is increased by a factor of up to 2 in a step‐wise manner when samples are uniaxially deformed past the yield point.
18.
Polydimethylsiloxane Fluidic Device with Polydopamine‐Coated Inner Channel for Production of Uniform Droplets 下载免费PDF全文
A polydimethylsiloxane (PDMS)‐based fluidic device with two flow channels is fabricated by using a rapid prototyping method. The PDMS‐based fluidic device is used to produce water‐in‐oil emulsion (W/O) droplets due to its intrinsic hydrophobicity. To produce uniform oil‐in‐water (O/W) emulsion droplets, the inner channel of the PDMS fluidic device is coated with polydopamine (PDA) by flowing a dopamine precursor in the water channel of the fluidic device. The PDA coating is confirmed by an increase in morphological roughness and nitrogen content. In addition, the contact angle of the PDMS surface decreases from 95° to 30° during PDA coating, suggesting that the inner surface of the fluidic device is hydrophilic. Uniform W/O and O/W emulsion droplets are produced by the pristine PDMS and PDA‐coated PDMS fluidic devices, respectively.
19.
Self‐Cleaning,Thermoresponsive P(NIPAAm‐co‐AMPS) Double Network Membranes for Implanted Glucose Biosensors 下载免费PDF全文
Ruochong Fei A. Kristen Means Alexander A. Abraham Andrea K. Locke Gerard L. Coté Melissa A. Grunlan 《大分子材料与工程》2016,301(8):935-943
A self‐cleaning membrane that periodically rids itself of attached cells to maintain glucose diffusion could extend the lifetime of implanted glucose biosensors. Herein, we evaluate the functionality of thermoresponsive double network (DN) hydrogel membranes based on poly(N‐isopropylacrylamide) (PNIPAAm) and an electrostatic co‐monomer, 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS). DN hydrogels are comprised of a tightly crosslinked, ionized first network [P(NIPAAm‐co‐AMPS)] containing variable levels of AMPS (100:0–25:75 wt% ratio of NIPAAm:AMPS) and a loosely crosslinked, interpenetrating second network [PNIPAAm]. To meet the specific requirements of a subcutaneously implanted glucose biosensor, the volume phase transition temperature is tuned and essential properties, such as glucose diffusion kinetics, thermosensitivity, and cytocompatibility are evaluated. In addition, the self‐cleaning functionality is demonstrated through thermally driven cell detachment from the membranes in vitro.
20.
Application of Gurson Model for Evaluation of Density‐Dependent Mechanical Behavior of Polyurethane Foam: Comparative Study on Explicit and Implicit Method 下载免费PDF全文
Recently, liquefied natural gas (LNG) is a focus of interest around the world for several reasons, and LNG cargo containment systems (CCS) increase in quality to prevent loss of LNG during shipping. For insulation of CCS, polyurethane foam (PUF), an outstanding insulation material, is commonly used. However, until now, although its mechanical properties are relatively good, the material is not considered as a structural member under compressive loading, principal load direction in CCS. Moreover, as PUF is a porous material by mixing and foaming, its mechanical properties depend on voids, which is a dominant parameter for density. Therefore, in the present study, nonlinear behavior of PUF is described using Gurson model with a novel technique, i.e., an acceleration factor. The model expresses the behavior through the volume fraction of voids with consideration of the density effect to evaluate structural performance using user‐defined material subroutine with explicit and implicit methods.