One-Pot Controlled Synthesis of Homopolymers and Diblock Copolymers Grafted Graphene Oxide Using Couplable RAFT Agents

Abstract

An original strategy is presented to synthesize homopolymers and diblock copolymers grafted graphene oxide by simultaneous coupling reaction and RAFT process. Zfunctionalized S-methoxycarbonylphenylmethyl S′-3-(trimethoxysilyl)propyltrithiocarbonate (MPTT) and R-functionalized S-4-(trimethoxysilyl)benzyl S′-propyltrithiocarbonate (TBPT) were used as couplable RAFT agents to prepare the target nanocomposites. Under similar conditions, MPTTmediated grafting reaction was liable to afford grafted chains with shorter chain length, narrower molecular weight distribution and lower grafting density than TBPT-based reaction owing to increased shielding effect and different grafting process. The grafted polymers had nearly controlled molecular weight and polydispersity ranging between 1.11 and 1.38, and the apparent molar grafting ratio was estimated to be 73.6−220 μmol/g as the molecular weights of grafted polymers were in the range of 3980−12500 g/mol. The improved solubility and dispersibility of GO−polymer composites in various solvents comprising hexane and water confirmed their amphiphilicity. The grafting process offers an opportunity to alter GO morphologies, and surface morphologies involving nanosheets, nanoparticles, and nanorods were observed as the composites were dispersed in different solvents with the aid of sonication treatment. This tandem approach is promising for surface modification of solid substrates with hydroxyl surface due to its mild conditions, straightforward synthesis and good controllability.

Modification of graphene/graphene oxide with polymer brushes using controlled/living radical polymerization

“…Jiang et al92 modified GO with various polymers (styrene, NIPAM, N , N ,‐dimethyl acrylamide, methyl acrylate, and t ‐butyl acrylate) by use of a tandem approach involving “simultaneous” coupling of the RAFT agent S ‐4‐(trimethoxysilyl)benzyl S '‐propyltrithiocarbonate via the R‐group and RAFT polymerization initiated by AIBN at 60 °C in DMF in a one‐pot procedure. Reasonable control/livingness was observed, with brushes of M n ≈ 4000–12,000 g/mol and M w / M n ≈ 1.3.…”

Temperature responsive polymer brushes grafted from graphene oxide: an efficient fluorescent sensing platform for 2,4,6-trinitrophenol

“…The strong band at 1654 cm -1 is corresponding to the stretching vibrations of N-H and the other two bands are originated from the C-H vibrations of -CH(CH 3 ) 2 in PNIPAM. [36][37][38][39][40] The D band arises due to the vibration of carbon atoms with dangling bonds in plane terminations of disordered graphite, confirming the formation of sp 3 carbon in GO. 35 After acidification (Fig.1e), the band at 906 cm -1 disappears, illustrating that the ring-opening reaction of epoxy groups of PGMA units occurs.…”

“…36,37 The G bands in GO-RAFT and block copolymer brush-GO hybrids exhibit a gradual blue shift from 1609 to 1595 cm −1 . 38,42 When a comparison is made between pure GO and Alq 3 -containing block copolymer brush-GO hybrid (Fig.3b), we can clearly see that the resulting Alq 3 -containing block copolymer brush-GO hybrid presents the thin homogeneous polymer layer on the surface of GO with the black patches over the GO sheets. 37 Generally, the intensity ratio of D and G bands (I D /I G ) is the common metric that is used to characterize the defect density of graphene.…”

Grafting polymerization of single‐handed helical poly(phenyl isocyanide)s on graphene oxide and their application in enantioselective separation

“…Surface functional groups in GO such as hydroxyls, epoxides, and carboxylic acids can provide the suitable and enough reaction sites to couple or initiate polymer chains. Based on this strategy, GO nanocomposites grafted with various functional polymers have been prepared by a variety of methods including in situ polymerization, coupling reaction, ultrasonic irradiation, photopolymerization, and living/control polymerization such as atom transfer radical polymerization and reversible addition–fragmentation chain transfer polymerization.…”