Effect of block molecular weight distribution on the structure formation in block copolymer/homopolymer blends

2011 ◽  
Vol 50 (2) ◽  
pp. 106-116 ◽  
Author(s):  
Jessica Listak ◽  
Xiaolong Jia ◽  
Andrzej Plichta ◽  
Mingjiang Zhong ◽  
Krzysztof Matyjaszewski ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Block Copolymer ◽  
Structure Formation ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Homopolymer Blends

scholarly journals Exploiting Molecular Weight Distribution Shape to Tune Domain Spacing in Block Copolymer Thin Films

2018 ◽  
Vol 140 (13) ◽  
pp. 4639-4648 ◽  
Author(s):  
Dillon T. Gentekos ◽  
Junteng Jia ◽  
Erika S. Tirado ◽  
Katherine P. Barteau ◽  
Detlef-M. Smilgies ◽  
...  
Keyword(s):  
Thin Films ◽  
Molecular Weight ◽  
Block Copolymer ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Distribution Shape

scholarly journals Preparation of Quaternary Amphiphilic Block Copolymer PMA-b-P (NVP/MAH/St) and Its Application in Surface Modification of Aluminum Nitride Powders

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 5884
Author(s):  
Yu Wang ◽  
Guangdong Zhu ◽  
Shun Wang ◽  
Jianjun Xie ◽  
Zhan Chen ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Block Copolymer ◽  
Aluminum Nitride ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Hot Water ◽  
Amphiphilic Block Copolymer ◽  
Vinyl Pyrrolidone ◽  
Charge Transfer Complexes ◽  
Nuclear Magnetic Spectroscopy

Poly(methyl acrylate)-b-poly(N-vinyl pyrrolidone/maleic anhydride/styrene) (PMA-b-P (NVP/MAH/St)) quaternary amphiphilic block copolymer prepared by reversible addition-fragmentation chain transfer (RAFT) was used to improve the anti-hydrolysis and dispersion properties of aluminum nitride (AIN) powders that were modified by copolymers. Its structure was characterized by Fourier transform infrared spectroscopy (FT-IR) and Hydrogen nuclear magnetic spectroscopy (1H-NMR). The results demonstrate that the molecular weight distribution of the quaternary amphiphilic block copolymers is 1.35–1.60, which is characteristic of controlled molecular weight and narrow molecular weight distribution. Through charge transfer complexes, NVP/MAH/St produces a regular alternating arrangement structure. After being treated with micro-crosslinking, AlN powder modified by copolymer PMA-b-P(NVP/MAH/St) exhibits outstanding resistance to hydrolysis and can be stabilized in hot water at 50 °C for more than 14 h, and the agglomeration of powder particles was improved remarkably.

Extraction and Partial Purification of Protease from Bilimbi (Averrhoa bilimbi L.)

2013 ◽  
Vol 10 (2) ◽  
pp. 29
Author(s):  
Normah Ismail ◽  
Nur' Ain Mohamad Kharoe
Keyword(s):  
Molecular Weight ◽  
Protein Content ◽  
Ammonium Sulfate ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Protease Activity ◽  
Protein Concentration ◽  
Temperature Stability ◽  
Partial Purification ◽  
Ammonium Sulfate Precipitation

Unripe and ripe bilimbi (Averrhoa bilimbi L.) were ground and the extracted juices were partially purified by ammonium sulfate precipitation at the concentrations of 40 and 60% (w/v). The collected proteases were analysed for pH, temperature stability, storage stability, molecular weight distribution, protein concentration and protein content. Protein content of bilimbi fruit was 0.89 g. Protease activity of both the unripe and ripe fruit were optimum at pH 4 and 40°C when the juice were purified at 40 and 60% ammonium sulfate precipitation. A decreased in protease activity was observed during the seven days of storage at 4°C. Molecular weight distribution indicated that the proteases protein bands fall between IO to 220 kDa. Protein bands were observed at 25, 50 and 160 kDa in both the unripe and ripe bilimbi proteases purified with 40% ammonium sulfate, however, the bands were more intense in those from unripe bilimbi. No protein bands were seen in proteases purified with 60% ammonium sulfate. Protein concentration was higher for proteases extracted with 40% ammonium sulfate at both ripening stages. Thus, purification using 40% ammonium sulfate precipitation could be a successful method to partially purify proteases from bilimbi especially from the unripe stage. 

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