High Tm linear poly(l-lactide)s prepared via alcohol-initiated ROPs of l-lactide

RSC Advances ◽  
2021 ◽  
Vol 11 (23) ◽  
pp. 14093-14102
Author(s):  
Hans R. Kricheldorf ◽  
Steffen M. Weidner ◽  
Andreas Meyer
Keyword(s):  
High Melting ◽  
Reaction Conditions ◽  
Linear Poly ◽  
A Performance

By variation of reaction conditions and catalysts a cyclic tin(ii) compound was found, which enables synthesis of high melting (>190 °C) poly(l-lactide) via ROP of l-lactide, whereas the technically used catalyst SnOct2 does not show such a performance.

Synthesis and Characterization of Polysulfonyldiphenylene Phenylphosphonate with High Melting Range

2011 ◽  
Vol 396-398 ◽  
pp. 2342-2345
Author(s):  
Zhong Wei Wang ◽  
Hao Dong Duan ◽  
Qing Yu
Keyword(s):  
Thermal Stability ◽  
Reaction Time ◽  
Thermogravimetric Analysis ◽  
Synthesis And Characterization ◽  
Target Product ◽  
High Melting ◽  
Melting Range ◽  
Reaction Conditions ◽  
Good Thermal Stability

Polysulfonyldiphenylene phenylphosphonate (PSPPP) with high melting range of 197 to 205 °C was synthesized via molten polycondensation method. The effect of material ratio, reaction temperature and reaction time of the method was studied, and the preferred reaction conditions were obtained. The target product was characterized by FTIR and thermogravimetric analysis (TGA) was carried out to confirm the thermal stability. The PSPPP synthesized in this paper showed fairly good thermal stability.

scholarly journals Synthesis of 1,1,3,3,5,5-Hexamethyl-7,7-diorganocyclotetrasiloxanes and Its Copolymers

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 28
Author(s):  
Evgeniya V. Talalaeva ◽  
Aleksandra A. Kalinina ◽  
Evgeniy V. Chernov ◽  
Alina G. Khmelnitskaia ◽  
Marina A. Obrezkova ◽  
...  
Keyword(s):  
Reaction Conditions ◽  
Preparative Yield ◽  
Linear Poly ◽  
Regular Alternation

This paper reports a method for the synthesis of 1,1,3,3,5,5-hexamethyl-7,7-diorganocyclotetrasiloxanes by the interaction of 1,5-disodiumoxyhexamethylsiloxane with dichlorodiorganosilanes such as methyl-, methylvinyl-, methylphenyl-, diphenyl- and diethyl dichlorosilanes. Depending on the reaction conditions, the preparative yield of the target cyclotetrasiloxanes is 55–75%. Along with mixed cyclotetrasiloxanes, the proposed method leads to the formation of polymers with regular alternation of diorganosylil and dimethylsylil units. For example, in the case of dichlorodiethylsilane, 70% content of linear poly(diethyl)dimethylsiloxanes with regular alternation of units can be achieved in the reaction product. Using 7,7-diethyl-1,1,3,3,5,5-hexamethylcyclotetrasiloxane as an example, the prospects of the mixed cycle in copolymer preparation in comparison with the copolymerization of octamethyl- and octaethylcyclotetrasiloxanes are shown.

Undecagold labeling of tRNA

1991 ◽  
Vol 49 ◽  
pp. 44-45
Author(s):  
James F. Hainfeld ◽  
Kyra M. Alford ◽  
Mathias Sprinzl ◽  
Valsan Mandiyan ◽  
Santa J. Tumminia ◽  
...  
Keyword(s):  
High Resolution ◽  
Transmission Electron Micrograph ◽  
Anticodon Loop ◽  
Electron Micrograph ◽  
Reaction Conditions ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

The undecagold (Au11) cluster was used to covalently label tRNA molecules at two specific ribonucleotides, one at position 75, and one at position 32 near the anticodon loop. Two different Au11 derivatives were used, one with a monomaleimide and one with a monoiodacetamide to effect efficient reactions.The first tRNA labeled was yeast tRNAphe which had a 2-thiocytidine (s2C) enzymatically introduced at position 75. This was found to react with the iodoacetamide-Aun derivative (Fig. 1) but not the maleimide-Aun (Fig. 2). Reaction conditions were 37° for 16 hours. Addition of dimethylformamide (DMF) up to 70% made no improvement in the labeling yield. A high resolution scanning transmission electron micrograph (STEM) taken using the darkfield elastically scattered electrons is shown in Fig. 3.

A Tem Study of Slip Systems in MoSi2/WSi2 Alloys

1991 ◽  
Vol 49 ◽  
pp. 942-943
Author(s):  
Stuart A. Maloy
Keyword(s):  
Solid Solution ◽  
Solid Solution Hardening ◽  
Slip Systems ◽  
High Melting ◽  
Group 14 ◽  
Solution Hardening ◽  
Brittle To Ductile Transition ◽  
High Melting Temperature ◽  
Tetragonal Unit Cell ◽  
Structural Applications

MoSi2 has recently been investigated as a potential material for high temperature structural applications. It has excellent oxidation resistance up to 1700°C, a high melting temperature, 2030°C, and a brittle-to-ductile transition temperature at 900-1000°C. WSi2 is isomorphous with MoSi2 and has a body-centered tetragonal unit cell of the space group 14/mmm. The lattice parameters are a=3.20 Å and c=7.84 Å for MoSi2 and a=3.21 Å and c=7.88 Å for WSi2. Therefore, WSi2 was added to MoSi2 to improve its strength via solid solution hardening. The purpose of this study was to investigate the slip systems in polycrystalline MoSi2/WSi2 alloys.

A performance schedule for extended space flight with the chimpanzee.

1962 ◽  
Author(s):  
F. H. Rholes ◽  
H. H. Reynolds ◽  
M. E. Grunzke ◽  
D. N. Farrer
Keyword(s):  
Space Flight ◽  
Extended Space ◽  
A Performance
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