j.polymer.2016.04.016
Synthesis and gas permeability of highly elastic poly(dimethylsiloxane)/graphene oxide composite elastomers using telechelic polymers
First, a known amount of telechelic PDMS (for 1 wt % GO composites, 990 mg) was dissolved in THF (6 ml) while stirring to ensure complete dissolution of the polymers. Then, dried GO (10 mg) was suspended in the solution with vigorous stirring, and a homogeneous dispersion of GO in this solution was promoted by sonication using a 400 W probe sonicator (Branson Digital Sonifier 450) with 10% amplitude for 10 min (24 kJ) in an ice bath. It is noteworthy to point out that, although THF is not a good solvent for GOs, amine terminated telechelic PDMS can effectively act as a surfactant to assist in dispersing GOs homogeneously in THF through hydrogen bonding between amine ends and oxygen containing groups on GO surfaces. A good dispersion after sonication was confirmed by examining the residual liquid film in the vial while rolling the vial containing the solution and after pouring the majority of the solution into a PTFE dish for solution casting. In either case, the liquid film in the vial was essentially transparent (although brownish-black from the GO content) for all solution concentrations and no aggregates could be identified with the naked eye. This solution was immediately poured into a Teflon dish and covered in order to slowly evaporate the solvent thereby solution casting a film at room temperature. Solvent was evaporated for at least 2 days and then the sample was vacuum dried at room temperature for an additional day to make a homogenous PDMS/GO uncrosslinked liquid sol. In order to form a crosslinked elastomer, the sol precursor was heated to 160 degC in a vacuum oven for 24 h and cooled slowly to room temperature before use.
THF
6 ml
ml
GO composites
1 wt %
wt %
telechelic PDMS
dissolved
990 mg
mg
dried GO
suspended in the solution
10 mg
mg
probe sonicator (Branson Digital Sonifier 450)
400 W
W
solution
sonication
10 min
min
solution
sonication
24 kJ
kJ
sonication
amplitude
10%
%
Solvent
evaporated
2 days
days
sol precursor
heated
160 degC
degC
sol precursor
heated
24 h
h