Impact of Redox-Active Polymer Molecular Weight on the Electrochemical Properties and Transport Across Porous Separators in Nonaqueous Solvents

2014 ◽  
Vol 136 (46) ◽  
pp. 16309-16316 ◽  
Author(s):  
Gavvalapalli Nagarjuna ◽  
Jingshu Hui ◽  
Kevin J. Cheng ◽  
Timothy Lichtenstein ◽  
Mei Shen ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Electrochemical Properties ◽  
Nonaqueous Solvents ◽  
Polymer Molecular Weight ◽  
Redox Active

Crystallization of Isotactic Poly(propylene) in Solution as Followed by Slow Calorimetry

1995 ◽  
Vol 60 (11) ◽  
pp. 1905-1924 ◽  
Author(s):  
Hong Phuong-Nguyen ◽  
Geneviève Delmas
Keyword(s):  
Molecular Weight ◽  
Crystal Growth ◽  
High Temperature ◽  
Heat Of Fusion ◽  
Complete Dissolution ◽  
Polymer Molecular Weight ◽  
Solvent Quality ◽  
Temperature Ramp ◽  
Poly Propylene

Dissolution, crystallization and second dissolution traces of isotactic poly(propylene) have been obtained in a slow temperature ramp (3 K h-1) with the C80 Setaram calorimeter. Traces of phase-change, in presence of solvent, are comparable to traces without solvent. The change of enthalpy on heating or cooling, ∆Htotal, over the 40-170 °C temperature range, is the sum of two contributions, ∆HDSC and ∆Hnetwork. The change ∆HDSC is the usual heat obtained in a fast temperature ramp and ∆Hnetwork is associated with a physical network whose disordering is slow and subject to superheating due to strain. When dissolution is complete, ∆Htotal is equal to ∆H0, the heat of fusion of perfect crystals. The values of ∆Htota for nascent and recrystallized samples are compared. Dissolution is the tool to evaluate the quality of the crystals. The repartition of ∆Htotal, into the two endotherms, reflects the quality of crystals. The crystals grown more rapidly have a higher fraction of network crystals which are stable at high T in the solvents. A complete dissolution, i.e. a high temperature (170 °C or more) is necessary to obtain good crystals. The effect of concentration, polymer molecular weight and solvent quality on crystal growth is analyzed.

scholarly journals Insight to Microbial Fe(III) Reduction Mediated by Redox-Active Humic Acids with Varied Redox Potentials

2021 ◽  
Vol 18 (13) ◽  
pp. 6807
Author(s):  
Jingtao Duan ◽  
Zhiyuan Xu ◽  
Zhen Yang ◽  
Jie Jiang
Keyword(s):  
Molecular Weight ◽  
Electron Transfer ◽  
Humic Acids ◽  
Weight Fraction ◽  
Electrochemical Analysis ◽  
Microbial Reduction ◽  
Redox Potentials ◽  
Groundwater Environment ◽  
Redox Active ◽  
Different Molecular Weight

Redox-active humic acids (HA) are ubiquitous in terrestrial and aquatic systems and are involved in numerous electron transfer reactions affecting biogeochemical processes and fates of pollutants in soil environments. Redox-active contaminants are trapped in soil micropores (<2 nm) that have limited access to microbes and HA. Therefore, the contaminants whose molecular structure and properties are not damaged accumulate in the soil micropores and become potential pollution sources. Electron transfer capacities (ETC) of HA reflecting redox activities of low molecular weight fraction (LMWF, <2.5) HA can be detected by an electrochemical method, which is related to redox potentials (Eh) in soil and aquatic environments. Nevertheless, electron accepting capacities (EAC) and electron donating capacities (EDC) of these LMWF HA at different Eh are still unknown. EDC and EAC of different molecular weight HA at different Eh were analyzed using electrochemical methods. EAC of LMWF at −0.59 V was 12 times higher than that at −0.49 V, while EAC increased to 2.6 times when the Eh decreased from −0.59 V to −0.69 V. Afterward, LMWF can act as a shuttle to stimulate microbial Fe(III) reduction processes in microbial reduction experiments. Additionally, EAC by electrochemical analysis at a range of −0.49–−0.59 V was comparable to total calculated ETC of different molecular weight fractions of HA by microbial reduction. Therefore, it is indicated that redox-active functional groups that can be reduced at Eh range of −0.49–−0.59 are available to microbial reduction. This finding contributes to a novel perspective in the protection and remediation of the groundwater environment in the biogeochemistry process.

scholarly journals The Influence of Polymer Molecular Weight in Lamellar Gels Based on PEG-Lipids

1998 ◽  
Vol 75 (1) ◽  
pp. 272-293 ◽  
Author(s):  
Heidi E. Warriner ◽  
S.L. Keller ◽  
Stefan H.J. Idziak ◽  
Nelle L. Slack ◽  
Patrick Davidson ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Polymer Molecular Weight

Effects of drug and polymer molecular weight on drug release from PLGA-mPEG microspheres

2014 ◽  
Vol 132 (6) ◽  
pp. n/a-n/a ◽  
Author(s):  
Shuibin Feng ◽  
Lei Nie ◽  
Peng Zou ◽  
Jinping Suo
Keyword(s):  
Molecular Weight ◽  
Drug Release ◽  
Polymer Molecular Weight

Optimisation of diketopyrrolopyrrole:fullerene solar cell performance through control of polymer molecular weight and thermal annealing

2014 ◽  
Vol 2 (45) ◽  
pp. 19282-19289 ◽  
Author(s):  
Zhenggang Huang ◽  
Elisa Collado Fregoso ◽  
Stoichko Dimitrov ◽  
Pabitra Shakya Tuladhar ◽  
Ying Woan Soon ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Solar Cells ◽  
Solar Cell ◽  
Thermal Annealing ◽  
Bulk Heterojunction ◽  
Cell Performance ◽  
Polymer Molecular Weight ◽  
Solar Cell Performance ◽  
Heterojunction Solar Cells ◽  
Bulk Heterojunction Solar Cells

The performance of bulk heterojunction solar cells based on a novel donor polymer DPP-TT-T was optimised by tuning molecular weight and thermal annealing.

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