Accelerated development of human monocyte-macrophages cultured on Plastek-C tissue culture dishes

Summary Many investigators have found that the surface on which cells are cultured can be an important factor in their adherence and subsequent growth. To enhance the development of monocyte-macrophage cultures, we have grown these cells on polystyrene tissue cultureware that has been treated with gas plasma to induce a positively charged culture surface (Plastek-C cultureware from Tekmat). Human monocyte-macrophages grown on Plastek-C tissue cultureware demonstrated a greater cell protein content during culture development as compared to monocyte-macrophages grown on standard polystyrene tissue cultureware. Part of the reason for enhanced development of human monocyte-macrophage cultures on Plastek-C cultureware seemed to be due to a higher density of cells maintained during the initial stages of culture development.     

New Functionalized Anionic Initiators Prepared from Substituted 1,1‐Diphenylethylene Derivatives with Acetal‐Protected Monosaccharides and Their Application to Chain‐Multi‐Functionalized Polymers with Glucose and Galactose Molecules

Living anionic polymerizations of methyl methacrylate, tert‐butyl methacrylate, 2‐(perfluorobutyl)ethyl methacrylate, tert‐butyl acrylate, and ethylene oxide were carried out with functionalized initiators prepared from substituted 1,1‐diphenylethylene (DPE) derivatives with two and four acetal‐protected α‐D ‐glucofuranose and α‐D ‐galactopyranose residues and carbanionic species such as sec‐butyllithium (sec‐BuLi), cumylpotassium, lithium and potassium naphthalenides. In certain cases, either LiCl or diethylzinc was used as an additive to control the polymerization. Several new well‐defined chain‐end‐ and in‐chain‐functionalized polymers with two and four glucose and two galactose molecules were successfully synthesized by these living polymerizations followed by deprotection. We have proposed a promising iterative methodology based on a convergent approach, with which novel two dendritic substituted DPE derivatives with four and eight acetal‐protected D ‐glucofuranose residues can successively be synthesized. With use of the functionalized anionic initiators prepared from such dendritic DPE derivatives and sec‐BuLi in the polymerization of methyl methacrylate, well‐defined chain‐end‐functionalized poly(methyl methacrylate)s with four and eight glucose molecules were synthesized.

     

Microdome-Tunable Graphene/Carbon Nanotubes Pressure Sensors Based on Polystyrene Array for Wearable Electronics

Resistive pressure sensors are appealing due to having several advantages, such as simple reading mechanisms, simple construction, and quick dynamic response. Achieving a constantly changeable microstructure of sensing materials is critical for the flexible pressure sensor and remains a difficulty. Herein, a flexible, tunable resistive pressure sensors is developed via simple, low-cost microsphere self-assembly and graphene/carbon nanotubes (CNTs) solution drop coating. The sensor uses polystyrene (PS) microspheres to construct an interlocked dome microstructure with graphene/CNTs as a conductive filler. The results indicate that the interlocked microdome-type pressure sensor has better sensitivity than the single microdome-type and single planar-type without surface microstructure. The pressure sensor’s sensitivity can be adjusted by varying the diameter of PS microspheres. In addition, the resistance of the sensor is also tunable by adjusting the number of graphene/CNT conductive coating layers. The developed flexible pressure sensor effectively detected human finger bending, demonstrating tremendous potential in human motion monitoring.     

Analysis and Optimization of Dimensional Accuracy and Porosity of High Impact Polystyrene Material Printed by FDM Process: PSO,JAYA, Rao,and Bald Eagle Search Algorithms

High impact polystyrene (HIPS) material is widely used for low-strength structural applications. To ensure proper function, dimensional accuracy and porosity are at the forefront of industrial relevance. The dimensional accuracy cylindricity error (CE) and porosity of printed parts are influenced mainly by the control variables (layer thickness, shell thickness, infill density, print speed of the fused deposition modeling (FDM) process). In this study, a central composite design (CCD) matrix was used to perform experiments and analyze the complete insight information of the process (control variables influence on CE and porosity of FDM parts). Shell thickness for CE and infill density for porosity were identified as the most significant factors. Layer thickness interaction with shell thickness, infill density (except for CE), and print speed were found to be significant for both outputs. The interaction factors, i.e., shell thickness and infill density, were insignificant (negligible effect) for both outputs. The models developed produced a better fit for regression with an R² equal to 94.56% for CE, and 99.10% for porosity, respectively. Four algorithms (bald eagle search optimization (BES), particle swarm optimization (PSO), RAO-3, and JAYA) were applied to determine optimal FDM conditions while examining six case studies (sets of weights assigned for porosity and CE) focused on minimizing both CE and porosity. BES and RAO-3 algorithms determined optimal conditions (layer thickness: 0.22 mm; shell thickness: 2 mm; infill density: 100%; print speed: 30 mm/s) at a reduced computation time equal to 0.007 s, differing from JAYA and PSO, which resulted in an experimental CE of 0.1215 mm and 2.5% of porosity in printed parts. Consequently, BES and RAO-3 algorithms are efficient tools for the optimization of FDM parts.     

Thermal Analysis of Plastics Used in the Food Industry

Fires in landfills, where used plastic packaging waste is discarded, have shown how great a fire hazard these types of materials pose. In this study, the course of thermo-oxidation of samples made of polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET) based plastics was determined. Based on an analysis of the dissociation energy of bonds between atoms in a polymer molecule, the mechanisms responsible for the character and course of degradation were observed. It was found that the degradation rate of PP and PS could be a result of the stability of C-H bonds on the tertiary carbon atom. In the case of PS, due to facilitated intramolecular hydrogen transfer, stabilization of hydroperoxide, and formation of a stable tertiary alcohol molecule, the onset of degradation is shifted towards higher temperatures than in the case of PP. Notably, the PP fragmentation occurs to a greater extent due to the easier course of β-scission. In addition, it was found that during a fire, the least amount of heat would be generated by thermo-oxidation of PS-based plastics. This is a result of the formation of a styrene molecule during decomposition that, due to the high stability of bonds in the aromatic ring, escapes from the combustion zone without oxidation. It has been proven that the greatest thermal effect accompanies PET decomposition, during which a phenyl radical is produced, where the C-H bonds break more easily in comparison with the bonds of an intact ring.     

Control of the radical polymerization by 2,2,15,15‐tetramethyl‐1‐aza‐4,7,10,13‐tetraoxacyclopentadecan‐1‐oxyl and its sodium salt

The control of the radical polymerization of styrene by 2,2,15,15‐tetramethyl‐1‐aza‐4,7,10,13‐tetraoxacyclopentadecan‐1‐oxyl is reported here in bulk at 90 °C, 120 °C and in miniemulsion. Similarly, the control by its sodium complex is reported in bulk at 90 °C.

M _n vs. conversion for 3 , 3Na , and TEMPO.     

Graft Copolymerization of Styrene onto Ozonized Polyethylene

Grafting of styrene onto ozonized high and low density polyethylene (LDPE and HDPE) and characterization of the obtained grafted copolymers were investigated in this study. Previous works showed that grafting rates of styrene onto PE are low and do not exceed 30 wt.‐% when these reactions were carried out at 150°C. To improve grafting rates and increase the length of grafts, we have used specific catalysts which favor the decomposition of peroxide and hydroperoxide groups at lower temperature (40–60°C). The use of tertiary amines does not improve the grafting rates of copolymers. Inversely, cobalt salts such as cobalt naphthenate lead to better grafting and higher conversion rates, longer grafts and do not influence the thermal homopolymerization of styrene. To compare the length of grafts with these of the homopolymer formed, we used a heterolysis reaction of the ether bond. The results obtained show that a large part of grafts originate from C—O∗︁ radicals, indicating that the grafts are bound to PE by an ether bond.     

para‐Substituted Poly(styrene peroxide)s: Synthesis,Characterization, Thermal Reactivities,and Chain Dynamics Studies in Solution

The synthesis and spectroscopic characterization of three polymeric peroxides of styrene monomers with substituents in the para position are discussed. NMR spectroscopy revealed the alternating copolymer structure with labile peroxy bonds (—O—O—) in their main chain. The thermal reactivity of the polymers was studied by differential scanning calorimetry and thermogravimetry. The measured heat of degradation of these polymers is nearly the same as that of poly(styrene peroxide). The mechanism of the primary exothermic degradation has been substantiated by thermochemical calculations. The chain dynamics studies of these polyperoxides in terms of ¹³C spin‐lattice relaxation time (T₁) have been carried out to understand their main chain flexibility. The temperature dependence of correlation time has been utilized for the determination of the activation energy for the overall segmental motion and internal group rotation. Their flexibility in terms of glass transition temperature (T_g) have been examined. The flexibility trend observed in solution parallels that in the bulk.     

End‐Group Selectivity of Low‐Molecular‐Weight Polystyrenes on a Carbon‐Clad Zirconia Stationary Phase in Reversed‐Phase HPLC

The separation of isomers of polystyrene oligomers was demonstrated on a carbon‐clad zirconia stationary phase in an acetonitrile mobile phase. The carbon‐clad zirconia surface gave considerably better resolution of isomers than a C18 surface, and the separation was sensitive to the end group of the oligomer. Oligomers with sec‐butyl end groups displayed almost twice as many isomers as the corresponding n‐butyl oligomer on the carbon‐clad zirconia surface. These additional bands could be explained by the stereochemistry of the sec‐butyl end group. In addition, the migration rate of the polystyrene isomers was dependent upon the end group, with n‐butyl polystyrenes displaying significantly greater retention on the carbon‐clad zirconia stationary phase. In comparison, the selectivity of conventional C18 columns could not discriminate between the n‐butyl and sec‐butyl end groups.     

亚微米级聚苯乙烯/聚硅氧烷核壳粒子的制备及其应用

以乳液聚合制备的聚苯乙烯乳液为种子,加入甲基三甲氧基硅烷(MTMS)水解溶液进行缩聚反应,合成亚微米级聚苯乙烯/聚硅氧烷核壳粒子,并以此作为光散射剂添加至聚甲基丙烯酸甲酯(PMMA)树脂中,制备了光散射材料;考察了亚微米级核壳粒子添加在PMMA树脂中的分散性。结果表明:经过双螺杆剪切作用的挤出加工后,可以实现核壳粒子在PMMA树脂中的良好分散。核壳粒子可以大幅度提高PMMA的雾度,当聚苯乙烯/聚硅氧烷核壳粒子(NS82)的含量为1%时,制得的PMMA样片(厚度为2 mm)的雾度为89%,透光率为69%,有效光散射系数为61%。