Well-defined 4-arm stars with hydroxy-terminated polyethylene, polyethylene-b-polycaprolactone and polyethylene-b-(polymethyl methacrylate)2 arms

2016 ◽  
Vol 7 (35) ◽  
pp. 5507-5511 ◽  
Author(s):  
Zhen Zhang ◽  
Yves Gnanou ◽  
Nikos Hadjichristidis
Keyword(s):  
Polymethyl Methacrylate ◽  
Dimethylsulfoxonium Methylide

Bis-boron-thexyl-silaboracycle was used to initiate the polyhomologation of dimethylsulfoxonium methylide to afford well-defined hydroxy-terminated 4-arm polyethylene (PE) stars, which served as precursors for the synthesis of PE-based starblock copolymers.

scholarly journals Research and Prediction of Wettability of Irregular Square Column Structure on Polymethyl Methacrylate (PMMA) Surface Prepared by Femtosecond Laser

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 529
Author(s):  
Bangfu Wang ◽  
Juan Song
Keyword(s):  
Contact Angle ◽  
Femtosecond Laser ◽  
Prediction Model ◽  
Polymethyl Methacrylate ◽  
Groove Width ◽  
Complete Wetting ◽  
Column Structure ◽  
Pmma Surface ◽  
Incomplete Wetting ◽  
Wetting Model

Based on the contact angle prediction model of a traditional square column structure, the prediction models for wettability of a parallelogram square column structure (PSCS) on polymethyl methacrylate (PMMA) surface prepared by femtosecond laser were established. An experiment was conducted to analyze the rationality of the established complete wetting model and incomplete wetting model. It was found that the incomplete wetting prediction model of the square column structure was more in line with the actual situation. For PSCS, the length of both the long and short sides of the boss and the width of the groove exerted an impact on the contact angle prediction results. Under the condition that the length of the long and short sides of the boss remained unchanged and the groove width increased, the contact angle increased under complete wetting and incomplete wetting. In contrast, under the condition that the long side length of the boss and the groove width remained unchanged and the short side length of the boss increased, the contact angle increased under complete wetting but decreased under incomplete wetting. The maximum contact angle reached 135.65°, indicating that PSCS on PMMA surface enhanced the surface hydrophobicity of the material.

scholarly journals Thermodynamic and Kinetic Characteristics of Combustion of Discrete Polymethyl Methacrylate Plates with Different Spacings in Concave Building Facades

Polymers ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 167
Author(s):  
Weiguang An ◽  
Lujun Peng ◽  
Minglun Cai ◽  
Kaiyang Hu ◽  
Song Li ◽  
...  
Keyword(s):  
Polymethyl Methacrylate ◽  
Flame Spread ◽  
Structure Factor ◽  
Turning Point ◽  
Fire Risk ◽  
Flame Height ◽  
Hazard Evaluation ◽  
Spread Rate ◽  
Building Facades ◽  
Flame Spread Rate

Polymethyl methacrylate plates are widely applied to buildings, producing significant fire hazards. It lacks a theoretical basis for the fire risk assessment of polymethyl methacrylate in concave building facades. Therefore, experimental methods are used to investigate combustion characteristics of discrete polymethyl methacrylate plates in a concave building facade. Influences of fuel coverage and structure factor are investigated, which is scant in previous works. When structure factor is invariable, average flame height increases first and then decreases as fuel coverage increases, and the turning point is between 0.64 and 0.76. In total, three different patterns of pyrolysis front propagation are first observed for different fuel coverages. Flame spread rate first increases and then decreases as fuel coverage rises, and the turning point is also between 0.64 and 0.76. When fuel coverage is invariable, the flame spread rate first increases and then decreases with increasing structure factor, and the turning point is 1.2. A model for predicting the flame spread rate of discrete polymethyl methacrylate is also developed. The predicted values are consistent with experimental results. Fuel spread rate of discrete polymethyl methacrylate rises as the fuel coverage increases. The above results are beneficial for thermal hazard evaluation and fire safety design of polymethyl methacrylate used in buildings.

Does microwave and hydrogen peroxide disinfection reduce Candida albicans biofilm on polymethyl methacrylate denture surfaces?

2021 ◽  
Author(s):  
Ilse Verónica Martínez-Serna ◽  
Marine Ortiz Magdaleno ◽  
Juan Antonio Cepeda-Bravo ◽  
Gabriel Fernando Romo-Ramírez ◽  
Luis Octavio Sánchez-Vargas
Keyword(s):  
Hydrogen Peroxide ◽  
Candida Albicans ◽  
Polymethyl Methacrylate
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