Synthesis of Dual Thermosensitive and pH-Sensitive Hollow Nanospheres Based on Poly(acrylic acid-b-2-hydroxyethyl methacrylate) via an Atom Transfer Reversible Addition–Fragmentation Radical Process

Abstract

A seven-step approach was developed to synthesize poly(acrylic acid-b-2-hydroxyethyl methacrylate) [P(AA-b-HEMA)]-based temperature-and pH-sensitive hollow nanospheres. Silica nanoparticles were used as primary cores that could be etched with an aqueous hydrofluoric acid (HF) solution. A surface-attached atom transfer radical polymerization initiator was converted to a reversible addition−fragmentation chain transfer (RAFT) agent, and AA and HEMA were polymerized via "grafting from" RAFT polymerization. The PAA block was cross-linked partially via an esterification reaction with -COOH groups with 1,4-butanediol, and hollow nanospheres were obtained by etching silica cores with an aqueous HF solution. These hollow nanospheres exhibited dual pH-sensitive and thermosensitive properties as measured by the hydrodynamic diameter at different values of pH (3−12) and temperature (25−55 °C) at different concentrations (1 and 5 mg/mL). Results showed that this behavior could be changed at different concentrations; therefore, at low contents, the particles show one lower critical solution temperature (LCST), while at higher contents, two LCSTs are observed.

A temperature-controlled method to produce Janus nanoparticles using high internal interface systems: Experimental and theoretical approaches

“…The first small amount of weight loss (2 wt. %) in both Janus samples is attributed to evaporation of water adsorbed on the surface of nanoparticles [33]. The second weight loss in both Janus samples is mainly due to the degradation of -NH2 and -CH2-groups.…”

Synthesis of poly(2-hydroxyethyl methacrylate)-grafted poly(aminoamide) dendrimers as polymeric nanostructures

“…% excess of methyl acrylate was used while to synthesize amine-terminated dendrimers, molar ration of [EDA]/[ester groups] was 15-20. After reaction, the solvent was removed under reduced pressure at 50°C for 48 h. Synthesis of RAFT agent-attached 4.0GD dendrimer (4.0GD-R) 4.0GD dendrimer ideally contains 64 primary amine groups on its surface. These amine groups can be used as functional groups to attach carboxylic acid-containing RAFT agent.…”

“…Recently, different polymeric nanostructures such as inorganic/polymeric hybrid nanoparticles [1,2], hollow nanostructures [3,4], and dendrimers [5,6] have got much attention due to their applications in drug delivery [7], gene delivery [8], etc. Among mentioned structures, dendrimers as three-dimensional (3D), highly branched, and monodispersed nanostructures are obtained by iterative sequence of reaction steps [9,10].…”

Grafting of pH-sensitive poly (N,N-dimethylaminoethyl methacrylate-co-2-hydroxyethyl methacrylate) onto HNTS via surface-initiated atom transfer radical polymerization for controllable drug release

“…Surface initiated atom transfer radical polymerization (SI-ATRP) is widely used to attach well-defined and narrowlydispersed polymer chains via "grafting from" approach. Also, ATRP reaction is tolerant to various reaction conditions and variety of monomer functionalities [27]. Well-defined polymers have been grafted onto different substrates by atom transfer radical polymerization [28][29][30][31][32][33][34][35].…”