Facile and controllable synthesis of hybrid silica nanoparticles densely grafted with poly(ethylene glycol)

Abstract

We report that a mixture of good and poor solvents greatly enhances the grafting density of nanosized silica grafted with poly(ethylene glycol) (PEG) by the ‘grafting to’ method. Methoxypolyethylene glycol (MPEG) (molecular weight 750, 2000 and 4000 g mol−1) was modified in a controlled manner to prepare epoxide terminated PEG (MPEG‐EO). Silica nanoparticles were modified with N‐(2‐aminoethy)‐3‐aminopropylmethyldimethoxysilane through the silanization coupling reaction to obtain a well‐defined siloxane structure. MPEG‐EO was coupled to the modified silica by the reaction of their terminal groups in a mixed solvent (n‐decane/toluene). The grafting density of MPEG‐EO was found to be controlled by the concentration of MPEG‐EO and the ratio of n‐decane to toluene in the grafting system. Based on TGA, the maximum grafting density was found to be about 2.8, 1.47 and 0.76 chains nm−2 for molecular weights of 750, 2000 and 4000, respectively, which is extremely high compared to previous reports. This high grafting density can be explained by the decreased chain dimension of PEG in the presence of the poor solvent. The method can be applied to other nanoparticles and polymers which can greatly enhance the application of SiO2 nanocomposites. © 2017 Society of Chemical Industry

Facile meltPEGylation of flame-made luminescent Tb3+-doped yttrium oxide particles: hemocompatibility, cellular uptake and comparison to silica

“…For comparison, surface grafting densities for functionalization with commercially available PEG-silanes following the protocol described by Lucky et al 39 were included in Table 1. Grafting densities obtained by the meltPEGylation route are comparable to reported maximum PEG densities on silica (0.24-2.3 chains per nm 2 ) 40 and iron oxide (0.5-3 chains per nm 2 ). 23 Importantly, meltPEGylation can give access to a brush-like conformation of PEG.…”

Recovery of Polyphenols from Grape Pomace Using Polyethylene Glycol (PEG)-Grafted Silica Particles and PEG-Assisted Cosolvent Elution

“…The surface functional groups on the surface of silica particles were confirmed based on the presence of the characteristic peaks for different moieties, such as C=O, N−H, and −CH 2 (Figure 1). For both bare and mPEG-grafted silica particles, the peaks at ~1045 cm −1 are attributed to asymmetric vibrations of Si−O−Si [33]. A characteristic peak of carbonyl group (C=O) stretching in the range of 1715 ± 100 cm −1 appeared for mPEG-functionalized silica particles due to presence carbonyl groups in the mPEG–silane structure (Figure 1).…”

“…An −NH group is also present in the structure of mPEG silane due to coupling chemistry used. Moreover, the peak around 2800 ± 100 cm −1 appeared is attributed to −CH 2 stretching vibration from the repetitive units of mPEG grafted on silica particles [33,35]. The small peaks at ~1462 and 1347 cm −1 are attributed to −CH 2 bending and wagging vibration, respectively [33,35].…”

“…Moreover, the peak around 2800 ± 100 cm −1 appeared is attributed to −CH 2 stretching vibration from the repetitive units of mPEG grafted on silica particles [33,35]. The small peaks at ~1462 and 1347 cm −1 are attributed to −CH 2 bending and wagging vibration, respectively [33,35]. In summary, identification of characteristic peaks of carbonyl (C=O), N−H, and −CH 2 suggest that successful coupling of mPEG–silane to silica particles was achieved.…”

Acrylic acid/allyloxy polyethylene glycol copolymer with methoxysilicon end groups as a highly effective dispersant for nano‐SiO2aqueous system

“…During the past several decades, many methods have been used to modify the surface of nano‐SiO 2 particles. Among them, grafting polymers on the surface of nano‐SiO 2 has attracted much attention because polymers have long molecular chain, easily adjustable structure and the high degree of the modification for nanoparticles . For example, Lin et al .…”