The Synthesis Of SiO₂ Nanotubes Based On Unimolecular Bottlebrush-Like Copolymers And Application As General Template

Owing to the hollow interior offering the ability for encapsulating reactive compounds as nanoreactors or loading guest molecules for delivery application,silica(SiO2)nanotubes have attracted much research attention.At present,there are relatively few effective methods for the preparation of size-controlled SiO2 nanotubes,and a typical strategy is in situ growth of SiO2 by using linear block copolymer self-assembled micelles as templates.However,there are still some bottlenecks in this method that need to be solved:(1)The dynamical stability of multimolecular micelles can be greatly affected by the external environment(temperature,solvent properties,etc.),and lead to the difficult precise control of the size and shape of self-assembled structure;(2)The amphiphilicity of the linear block copolymers is not only basic for the formation of functional micelles via self-assembly,but also limits the function and composition of the selected copolymers;(3)The formation of multimolecular micelles of linear block copolymer through self-assembly process is complicated.So a general template strategy for noble metal nanorods with controlled dimensions and tunable surface chemistry by water-soluble size-tunable nanotubes based on unimolecular bottlebrush-like block copolymers was developed,aims to solve the current shortcomings in the polymer template method,and promotes the practical applications of one-dimensional noble metal nanomaterials.Cylindrical bottlebrush-like diblock copolymers were firstly crafted through atom transfer radical polymerization(ATRP)with cellulose as the backbone,styrene(St)as the first monomer and 3-(isobutylene acyl oxygen)propyl silane(TMSPMA)as the second monomer.Water-soluble Organic-silica hybrid core/shell nanorods were then formed under alkali catalyst which causes the crosslinking of(Si(OCH3)3)in outer trimethoxysilyl moieties.Size-controlled water-soluble SiO2 nanotubes can be achieved after the selectively removing of the inner polymeric core.Then water-soluble size-tunable silica nanotubes can be utilized as general templates to fabricate a variety of noble metal nanorods,including Au,Ag,Pt,etc.The length and diameter of noble metal nanorods can be precisely tuned by controlling the dimensions of the interior cavity of silica nanotubes.At last,the functional group-terminated polymers,such as PS-SH or PEG-SH,were chosen as functional ligands for the surface modification of nanorods to fabricate organic solvent-soluble or water-soluble colloidal noble metal nanorods.This general strategy affords a variety of noble metal nanorods with well-controlled dimensions and surface chemical properties,which may find wide applications in many fields,such as catalysis,photonics,sensing,biomedicine and so on.