Thermo-Responsive Graphene Oxide/Poly(Ethyl Ethylene Phosphate) Nanocomposite via Ring Opening Polymerization.

Xue Jiang,Hong Chen,Fangqi Cao,Guolin Lu,Yu Li,Wenbin Liu,Xiaoyu Huang

doi:10.3390/nano9020207

Xue Jiang, Hong Chen + Show 5 more

Open Access

https://doi.org/10.3390/nano9020207

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Abstract

An efficient strategy for growing thermo-sensitive polymers from the surface of exfoliated graphene oxide (GO) is reported in this article. GO sheets with hydroxyls and epoxy groups on the surface were first prepared by modified Hummer’s method. Epoxy groups on GO sheets can be easily modified through ring-opening reactions, involving nucleophilic attack by tris(hydroxymethyl) aminomethane (TRIS). The resulting GO-TRIS sheets became a more versatile precursor for next ring opening polymerization (ROP) of ethyl ethylene phosphate (EEP), leading to GO-TRIS/poly(ethyl ethylene phosphate) (GO-TRIS-PEEP) nanocomposite. The nanocomposite was characterized by 1H NMR, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential thermal gravity (DTG), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Since hydrophilic PEEP chains make the composite separate into single layers through hydrogen bonding interaction, the dispersity of the functionalized GO sheets in water is significantly improved. Meanwhile, the aqueous dispersion of GO-TRIS-PEEP nanocomposite shows reversible temperature switching self-assembly and disassembly behavior. Such a smart graphene oxide-based hybrid material is promising for applications in the biomedical field.

Highlights

Graphene oxide (GO), a single layer of carbon atoms in a closely packed honeycomb two-dimensional lattice with carboxylic acid, epoxide, and hydroxyl groups, has attracted considerable attention in recent years [1–9]
The fabrication process of GO-tris(hydroxymethyl) aminomethane (TRIS)-PEEP polymer-modified nanocomposite via ring opening polymerization of ethylene phosphate (EEP) monomer is outlined in Scheme 1
The obtained epoxy groups can be modified through ring-opening reactions, on the basis of the mechanism of nucleophilic attack by amine groups [17]. 1,1,1-Tris(hydroxymethyl) methanamine (TRIS) is a kind of primary amine with three hydroxyls, which has been extensively used in chemical modification of macroporous materials [41,42]

Summary

Introduction

Graphene oxide (GO), a single layer of carbon atoms in a closely packed honeycomb two-dimensional lattice with carboxylic acid, epoxide, and hydroxyl groups, has attracted considerable attention in recent years [1–9]. The presence of abundant functional groups at the surface of GO may be very interesting since that they provide enough reactive sites for the subsequent chemical modification using known carbon surface chemistry [14]. A considerable number of works have been performed on enhancing the properties of GO by adding additional functionality to the groups already present on the surface of GO [15–28]. “intelligentizing” graphene can been obtained by attaching stimuli-responsive polymers. Nanomaterials 2019, 9, 207 to the backbone of GO [21–28] These attachments are typically made by either grafting-from or -onto abpyperiotahcehregsr. Preparation of graphene oxide-tris(hydroxymethyl) aminomethane-poly(ethyl ethylene pShcohsepmheat1e). (PGreOp-aTrRaItSio-PnEoEfPg) rnaapnhoecnoemopxoidsiete-t.ris(hydroxymethyl) aminomethane-poly(ethyl ethylene phosphate) (GO-TRIS-PEEP) nanocomposite Preparation of graphene oxide-tris(hydroxymethyl) aminomethane-poly(ethyl ethylene pShcohsepmheat1e). (PGreOp-aTrRaItSio-PnEoEfPg) rnaapnhoecnoemopxoidsiete-t.ris(hydroxymethyl) aminomethane-poly(ethyl ethylene phosphate) (GO-TRIS-PEEP) nanocomposite

Experimental

Preparation of GO Sheets

Preparation of GO-TRIS-PEEP