Effect of Structure of Polymers Grafted from Graphene Oxide on the Compatibility of Particles with a Silicone-Based Environment and the Stimuli-Responsive Capabilities of Their Composites

Abstract

This study reports the utilization of controlled radical polymerization as a tool for controlling the stimuli-responsive capabilities of graphene oxide (GO) based hybrid systems. Various polymer brushes with controlled molecular weight and narrow molecular weight distribution were grafted from the GO surface by surface-initiated atom transfer radical polymerization (SI-ATRP). The modification of GO with poly(n-butyl methacrylate) (PBMA), poly(glycidyl methacrylate) (PGMA), poly(trimethylsilyloxyethyl methacrylate) (PHEMATMS) and poly(methyl methacrylate) (PMMA) was confirmed by thermogravimetric analysis (TGA) coupled with online Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Various grafting densities of GO-based materials were investigated, and conductivity was elucidated using a four-point probe method. Raman shift and XPS were used to confirm the reduction of surface properties of the GO particles during SI-ATRP. The contact angle measurements indicated the changes in the compatibility of GOs with silicone oil, depending on the structure of the grafted polymer chains. The compatibility of the GOs with poly(dimethylsiloxane) was also investigated using steady shear rheology. The tunability of the electrorheological, as well as the photo-actuation capability, was investigated. It was shown that in addition to the modification of conductivity, the dipole moment of the pendant groups of the grafted polymer chains also plays an important role in the electrorheological (ER) performance. The compatibility of the particles with the polymer matrix, and thus proper particles dispersibility, is the most important factor for the photo-actuation efficiency. The plasticizing effect of the GO-polymer hybrid filler also has a crucial impact on the matrix stiffness and thus the ability to reversibly respond to the external light stimulation.

Structure/Properties Relationship of Anionically Synthesized Diblock Copolymers “Grafted to” Chemically Modified Graphene

“…Grafting polymers on modified graphene sheets results in nanocomposites presenting a combination of properties resulting from both materials, namely improved solubility and interfacial energy alternations [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ]. The reaction between polymers and graphene oxide nanosheets involves two methods and specifically the “ grafting from ” [ 17 ], where the GO–initiator complex is primarily prepared in order to initiate the polymerization from the GO surface, and the “ grafting to ” [ 18 ], where the polymeric precursor bearing a functional group reacts with the chemically modified GO [ 19 , 20 , 21 , 22 , 23 ]. Employing the “ grafting to ” method, better control over the polymer’s molecular characteristics can be realized and satisfactory dispersity, and solubility are achieved, while the “ grafting from ” method results in higher coupling yields, but limited control over the molecular characteristics is reported [ 24 ].…”

Electrorheological Fluids of GO/Graphene-Based Nanoplates

“…Kutalkova et al [ 80 ] prepared two kinds of GO/PHEMATMS composites with different molar masses by the SI-ATRP method, as shown in Figure 4 , and proved that the relaxation time and dielectric polarization strength of the composites had a direct influence on the ER effect. Zygo et al [ 81 ] also prepared four kinds of composite ER materials, GO/PMMA, GO/PBMA, GO/PGMA, and GO/PHEMATMS, and all of them showed improved ER effect. It was also found that GO/PHEMATMS, which is similar to silicon-based environment, showed the best suspension stability and ER effect, where the yield stress is neat GO < PMMA < PBMA < PGMA < PHEMATMS.…”

Effect of Nano-Sized Poly(Butyl Acrylate) Layer Grafted from Graphene Oxide Sheets on the Compatibility and Beta-Phase Development of Poly(Vinylidene Fluoride) and Their Vibration Sensing Performance

“…In agreement with the listed literature sources above, the compatibility of the particles and PVDF matrix seems to be crucial. In this respect the modification of the GO particles with various polymers was already developed by our group, when enhanced compatibility was obtained by grafting of poly(methyl methacrylate), poly(butyl methacrylate), poly(styrene), poly(glycidyl methacrylate) and finally, poly(trimethylsilyloxyethyl methacrylate) [ 50 , 51 , 52 ], and thus their stimuli-responsive capabilities were significantly improved. Moreover, such approach provides a considerably softer and more flexible composite than observed for composites consisting of neat particles [ 53 ].…”