Helix-sense-selective co-precipitation for preparing optically active helical polymer nanoparticles/graphene oxide hybrid nanocomposites

Abstract

Constructing optically active helical polymer based nanomaterials without using expensive and limited chirally helical polymers has become an extremely attractive research topic in both chemical and materials science. In this study, we prepared a series of optically active helical polymer nanoparticles/graphene oxide (OAHPNs/GO) hybrid nanocomposites through an unprecedented strategy-the co-precipitation of optically inactive helical polymers and chirally modified GO. This approach is named helix-sense-selective co-precipitation (HSSCP), in which the chirally modified GO acted as a chiral source for inducing and further stabilizing the predominantly one-handed helicity in the optically inactive helical polymers. SEM and TEM images show quite similar morphologies of all the obtained OAHPNs/GO nanocomposites; specifically, the chirally modified GO sheets were uniformly decorated with spherical polymer nanoparticles. Circular dichroism (CD) and UV-vis absorption spectra confirmed the preferentially induced helicity in the helical polymers and the optical activity of the nanocomposites. The established HSSCP strategy is thus proven to be widely applicable and is expected to produce numerous functional OAHPNs/GO nanocomposites and even the analogues.

Dispersion Polymerization of Substituted Acetylenes in the Presence of Chiral Source for Preparing Monodispersed Chiral Nanoparticles

“…It is further indicative of that the polymer chains in P-1 and P-2 nanoparticles formed helical conformations but with left-and right-handed helices in equal amount, referring to our earlier series of studies dealing with helical poly acetylenes and the particles thereof. [7][8][9][10][11][12] The obtained P-3 and P-4 nanoparticles were also characterized by CD and UV-vis techniques and the obtained spectra are presented in Figure 3A,B. In Figure 3A, intense mirror-image CD signals are observed at about 300 nm, in which P-3 nanoparticles show the minus signal while P-4 nanoparticles show the plus signal.…”

“…That is, the formation of hydrogen bonds between achiral monomers and chiral additives is a key factor for the successful chiral induction in HSSDP, which is also found and discussed in detail in our previous studies dealing with helix-sense-selective polymerizations. [7][8][9][10][11][12] Besides, we also found that the prepared chiral P-2 nanoparticles cannot retain their chirality after dissolution ( Figure S18, Supporting Information), that is, the induced predominated one-handed helixes can be maintained only in nanoparticle state. We think the cause of this phenomenon may be due to the thermodynamic control in the HSSDP process.…”

Preparation and Applications of Chiral Polymeric Particles

“…Apart from the CPPs constructed by pure racemic helical polymers, Deng's group prepared CPPs/GO hybrid nanocomposites by helix-sense-selective co-precipitations (HSSCP) of chirally modified GO and racemic helical polymers in THF/ water solution systems. [55] The chirally modified GO acted as a chiral source for inducing and further stabilizing the predominantly induced one-handed helicity in the optically inactive helical polymers. Three racemic helical polymers underwent HSSCP along with chirally modified GO resulting in CPPs/ GO hybrid materials.…”

Graphene Oxide (GO) as Stabilizer for Preparing Chirally Helical Polyacetylene/GO Hybrid Microspheres via Suspension Polymerization

“…Optically active helical polymers have attracted great attention owing to their fascinating helical structures and significant potentials in chiral recognition, chiral separation, and asymmetric catalysis . Optically active spheres combining the advantages of helical polymers and the strength of particulate materials become increasingly interesting as a newly emerging type of advanced materials . More importantly, spheres with remarkable optical activity are expected to be prepared from chirally helical polymers holding “chiral amplification” effects .…”

“…[20] Optically active spheres combining the advantages of helical polymers and the strength of particulate materials become increasingly interesting as a newly emerging type of advanced materials. [21][22][23][24] More importantly, spheres with remarkable optical activity are expected to be prepared from chirally helical polymers holding "chiral amplification" effects. [25,26] In our earlier studies, we have prepared optically active polymeric spheres constructed by chirally helical substituted polyacetylenes by diverse polymerization methods.…”