Fluorescent gold nanoparticles with chain-end grafted RAFT copolymers: influence of the polymer molecular weight and type of chromophore

2016 ◽  
Vol 7 (44) ◽  
pp. 6812-6825 ◽  
Author(s):  
Cristina Cepraga ◽  
Arnaud Favier ◽  
Frédéric Lerouge ◽  
Pierre Alcouffe ◽  
Cécile Chamignon ◽  
...  

Fluorescence of gold nanoparticles functionalized with chain-end grafted RAFT copolymers increases with polymer corona thickness.

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Norma A. Cortez-Lemus ◽  
Angel Licea-Claverie ◽  
Francisco Paraguay-Delgado ◽  
Gabriel Alonso-Nuñez

Poly(N,N′-diethylaminoethyl methacrylate) (PDEAEM) with different molecular weights was used to stabilize gold nanoparticles (AuNPs) obtained byin situreduction of tetrachloroauric acid using citrates under acidic conditions and in organic/alcoholic medium. The influence of the pH value on gold nanoparticle size in the presence of PDEAEM was investigated. Results show that the pH of the reacting mixture has a dramatic effect on the size, polydispersity, and morphology of the resulting AuNPs. Moreover, the size of the nanoparticles (NPs) may be modified by changing the solution’s pH or by changing the solvent type. Electron microscope images showed that the sizes of AuNPs coated with PDEAEM were not sensitive to the variation of the polymer molecular weight in the range between 9000 and 29300 g/mol; however their aggregation behavior depended strongly on the polymer molecular weight as revealed by dynamic light scattering studies. AuNPs stabilized with PDEAEM (AuNP@PDEAEM) are stable in water at acidic pH and in organic polar solvents.


1995 ◽  
Vol 60 (11) ◽  
pp. 1905-1924 ◽  
Author(s):  
Hong Phuong-Nguyen ◽  
Geneviève Delmas

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.


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

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

Cellulose ◽  
2011 ◽  
Vol 18 (4) ◽  
pp. 929-936 ◽  
Author(s):  
Yukiko Enomoto-Rogers ◽  
Hiroshi Kamitakahara ◽  
Arata Yoshinaga ◽  
Toshiyuki Takano

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