A Versatile Approach for the Synthesis of Antimicrobial Polymer Brushes on Natural Rubber/Graphene Oxide Composite Films via Surface-Initiated Atom-Transfer Radical Polymerization.

A simple strategy was adopted for the preparation of an antimicrobial natural rubber/graphene oxide (NR/GO) composite film modified through the use of zwitterionic polymer brushes. An NR/GO composite film with antibacterial properties was prepared using a water-based solution-casting method. The composited GO was dispersed uniformly in the NR matrix and compensated for mechanical loss in the process of modification. Based on the high bromination activity of α-H in the structure of cis-polyisoprene, the composite films were brominated on the surface through the use of N-bromosuccinimide (NBS) under the irradiation of a 40 W tungsten lamp. Polymerization was carried out on the brominated films using sulfobetaine methacrylate (SBMA) as a monomer via surface-initiated atom transfer radical polymerization (SI-ATRP). The NR/GO composite films modified using polymer brushes (PSBMAs) exhibited 99.99% antimicrobial activity for resistance to Escherichia coli and Staphylococcus aureus. A novel polymer modification strategy for NR composite materials was established effectively, and the enhanced antimicrobial properties expand the application prospects in the medical field.

Grafting photochromic spiropyran polymer brushes on graphene oxide surfaces via surface-initiated ring-opening metathesis polymerization.

A practical "grafting-from" strategy is described to grow photochromic polymer brushes bearing spiropyran (SP) functional groups on graphene oxide (GO) surfaces via surface-initiated ring-opening metathesis polymerization (SI-ROMP). The Grubbs II catalyst was fixed on the GO surface, and the norbornene derivatives functionalized using spiropyran were synthesized from this active site via the ROMP method. The results indicated that the spiropyran-modified polymer brushes were obtained on the GO surface in the form of thin films. The solubility of GO modified by spiropyran polymers (GO-SPs) in organic solvents was significantly improved. The GO-SPs exhibited excellent photochromic properties, including fast coloration/decoloration. The modified GO with an isomeric structure was colored in 90 s under ultraviolet irradiation and decolored in 360 s under white light. The fading kinetic rate in the dark was slow and the kinetic attenuation curve followed bi-exponential decay. The GO-SP composite materials took more than 2 h to return to thermodynamically stable forms. The reversible change in the water contact angle reached 8° after continuous cycling with ultraviolet and visible light. GO-SP maintained its photochromic performance and possessed excellent fatigue resistance after more than six successive UV/light cycles. This work describes a practical strategy for the preparation of photochromic polymer brush modified GO composite materials and extends the applications of GO in photochromic materials.

Preparation and Self-Cleaning Performance of High-Strength Double-Layer PVDF-PVC-Nano-Graphite/PVDF-PVC Super-Hydrophobic Composite Membrane.

The double-layer PVDF-PVC (D-PP/PP) super-hydrophobic composite membrane was prepared by the coating immersion phase separation method to enhance the mechanical properties of the composite membrane. The D-PP/PP super-hydrophobic membrane was prepared using the casting solution concentration of 12 wt% PVDF-PVC composite membrane as basement and 4% casting of PVDF-PVC coating. The contact angle of the D-PP/PP membrane was 150.4 ± 0.3°, and the scanning electron microscope showed that the surface of the D-PP/PP membrane was covered by a cross-linked micro-nano microsphere. The mechanical properties showed that the maximum tensile force of the D-PP/PP composite membrane was 2.34 N, which was 19.4% higher than that of PVDF-PVC (1.96 N). Nano-graphite was added to the coating layer in the experiment. The prepared double-layer PVDF-PVC-nano-graphite/PVDF-PVC (D-PPG/PP) composite membrane reached 153.7 ± 0.5°, the contact angle increasing by 3.3°. The SEM comparison showed that the D-PPG/PP composite membrane had a more obvious micro-nano level microsphere layer. The mechanical properties are also superior. By preparing the D-PP/PP membrane, the mechanical properties of the membrane were improved, and the super-hydrophobic property of the coating was also obtained. At the same time, it was found that adding nano-graphite to the coating layer can better improve the hydrophobic, mechanical, and self-cleaning properties of the D-PP/PP composite membrane.

Study of a Multiple Responses, High Deformation, and Programmable PLA-PPC/PVA-PDA Actuator.

The intelligent response actuators based on bilayer polymer can deform under the stimulation of temperature, humidity, light, and other external environment, which is the focus of research. However, achieving multiple responses, high deformation, and programmability is still one of the challenges for these actuators. Herein, a nondetachable bilayer structure, polylactic acid-polypropylene carbonate/polyvinyl alcohol-polydopamine (PLA-PPC/PVA-PDA) multiresponse programmable actuator is prepared by a simple scraping film method. Using PLA-PPC as the solvent-driven response layer, the effects of length, thickness, shape, and solvent vapor on the deformation of PLA-PPC/PVA-PDA actuators are studied. Among them, the high curvature of the film stimulated by ethyl acetate (EA) solution is 29.85 cm-1 . Using PVA-PDA as the response layer to water molecules and infrared (IR) light, the bilayer film shows excellent curling performance. Moreover, the dynamic processes of human clothing and biomimetic squid under solvent stimulation, the picture rolling motion under water molecule stimulation, the biomimetic flower blooming and merging under the synergistic of water molecules and IR light, and the deformation process of biomimetic mimosa under the competition between water molecules and IR light are simulated, which broadens the road for the development of intelligent driving materials.

The Preparation of Superhydrophobic Polylactic Acid Membrane with Adjustable Pore Size by Freeze Solidification Phase Separation Method for Oil-Water Separation.

An environmentally friendly pore size-controlled, superhydrophobic polylactic acid (PLA) membrane was successfully prepared by a simpler freeze solidification phase separation method (FSPS) and solution impregnation, which has application prospects in the field of oil-water separation. The pore size and structure of the membrane were adjusted by different solvent ratios and solution impregnation ratios. The PLA-FSPS membrane after solution impregnation (S-PLA-FSPS) had the characteristics of uniform pore size, superhydrophobicity and super lipophilicity, its surface roughness Ra was 338 nm, and the contact angle to water was 151°. The S-PLA-FSPS membrane was used for the oil-water separation. The membrane oil flux reached 16,084 L·m-2·h-1, and the water separation efficiency was 99.7%, which was much higher than that of other oil-water separation materials. In addition, the S-PLA-FSPS membrane could also be applied for the adsorption and removal of oil slicks and underwater heavy oil. The S-PLA-FSPS membrane has great application potential in the field of oil-water separation.

Preparation of a Series of Highly Efficient Porous Adsorbent PGMA-N Molecules and Its Application in the Co-Removal of Cu(II) and Sulfamethoxazole from Water.

This paper presents a highly efficient porous adsorbent PGMA-N prepared through a series of amination reactions between polyglycidyl methacrylate (PGMA) and different polyamines. The obtained polymeric porous materials were characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), specific surface area test (BET), and elemental analysis (EA). Thereinto, the PGMA-EDA porous adsorbent exhibited excellent ability to synergistically remove Cu(II) ions and sulfamethoxazole from aqueous solutions. Moreover, we studied the effects of pH, contact time, temperature, and initial concentration of pollutants on the adsorption performance of the adsorbent. The experimental results showed that the adsorption process of Cu(II) followed the pseudo-second-order kinetic model and Langmuir isotherm. The maximum adsorption capacity of PGMA-EDA for Cu(II) ions was 0.794 mmol/g. These results indicate that PGMA-EDA porous adsorbent has great potential for application in treating wastewater coexisting with heavy metals and antibiotics.

Improving the communication skills of medical students --A survey of simulated patient-based learning in Chinese medical universities.

BACKGROUND: It is useful to advance simulated patient (SP) participation in teaching to improve the communication skills of medical students, so this study aims to explore the current state of Chinese mainland SP education. METHODS: A cross sectional survey was designed utilizing well defined quantitative research methods and descriptive statistics. The questionnaire sought information which elucidated the current status of SP-based education, the origin of SP-based learning, SP training, challenges of this learning strategy and future developments. Questionnaires were distributed to 79 medical colleges in mainland China, and 68 were returned. Of these, 64 constituted valid responses (81%). RESULTS: The number of SP-based education activities in medical colleges offering 5-year、7-year and 8-year clinical medicine programs was significantly higher than that in medical colleges which offered only a single 5-year program (p < 0.01). Communication skills training accounted for 73% of the content of SP-based learning activities, and was expected to rise in the future to 90%, in response to a need to improve doctor-patient relationships. Persons recruited as 'simulated patients' included students (21% of the total), residents (49%), medical staff (15%) and teaching staff (14%). Colleges, planning a SP-based education program, preferred teachers (80%) and students (55%) to assume 'simulated patient' roles. In objective structured clinical education (OSCE) scenarios, co-scoring by both SPs and teachers featured more highly in the 'consultation' station and 'doctor-patient communication' station. A number of factors were identified as hindering future development and implementation of SP-based learning including budget restraints, SP selection and training. CONCLUSIONS: SP-based learning programs offer clear benefits for improving the clinical education of medical students and their communication skills. The main obstacles to achieving more widespread and higher quality SP-based education are insufficient funding and the lack of standardized training and performance evaluation processes for simulated patients. Medical colleges should consider reducing the proportion of students and teachers acting as SPs, and attract more citizens to participate in SP-based learning activities. Formalised training and evaluation of SPs performance are necessary to establish a 'standard simulated patient' for a particular medical discipline, thus improving SP-based activities and student learning.

Mechanochromic luminescence properties of fluoro-substituted pinene-containing cyclometalated platinum(II) complexes with multiple triplet excited states.

The structure-mechanochromism relationship is explored with respect to packing patterns and corresponding intermolecular interactions that are affected by the number and location of -F. The distinct and reversible mechanochormic luminescence (Δλem up to ca. 90 nm) of yellow solids (-)-1-Yg, (-)-2-Yg, and (-)-3-Yg was displayed with a simultaneous crystal-to-amorphous transformation. The change of multiple triplet excited states accounted for the mechanochormic luminescence, and a switch from the 3π,π* monomer to the excimer/3MMLCT occurred in the grinding process. The mechanical force led to perturbation in the molecular packing, and aggregates with effective PtPt and π-π interactions were formed in the amorphous phase, leading to the variation of excited states. The mechanochromic luminescence could be reverted by dropping in CH2Cl2 and could be cycled multiple times without perceivable performance degradation. This work gives a reference for designing mechanochromic luminescent materials toward multicolor and multicomponent responses.