Poly(ethylene glycol)-graft-poly(vinyl acetate) single-chain nanoparticles for the encapsulation of small molecules

Abstract

Amphiphilic poly(ethylene glycol)-graft-poly(vinyl acetate) copolymers with a low degree of grafting undergo self-folding in water driven by hydrophobic interactions, resulting in single-chain nanoparticles (SCNPs) possessing a hydrodynamic radius of about 10 nm. A temperature scan revealed a lower critical solution temperature (LCST)-type phase behavior. In addition, SAXS data collected close to the LCST showed that these SCNPs aggregate into one-dimensional elongated objects, preferentially. With respect to the typical linear complex-structured polymer chains, this material is ideally suited for industrial and/or biomedical applications because of its simple molecular architecture and persistence of SCNPs up to 100 mg mL. The so-obtained single-chain globular particles are able to swell upon loading with small hydrophobic molecules therefore promoting solubilization of flavors or drugs, which could be of interest in the food and pharmaceutical industry.

Associative properties of poly(ethylene glycol)–poly(vinyl acetate) comb-like graft copolymers in water

“…This coincides with the polymer's cloud point as determined in previous work. 34 The 20% sample does not show such a transition, as the SAXS pattern at 65°C is consistent with spherical objects and the structure factor signature is lost; this seems to suggest that the interactions leading to the formation of the bicontinuous structure are weak and easily disrupted at high temperatures. However, at higher polymer concentrations (ESI, Fig.…”

“…In the curve pertaining to the 10% polymer sample, the Q peak value (0.03 Å −1 ) translates into a real-space distance d SAXS = 2π/Q peak = 21.7 nm, which is in good agreement with the hydrodynamic diameter of PEG-g-PVAc single-chain nanoparticles as reported for highly diluted systems. 34 Therefore, d SAXS is likely the centreto-centre distance between SCNPs whose outer hydration shells are interacting. The SAXS pattern can be fitted ( Fig.…”

“…Previous studies have shown that the here reported comb-like PEG-g-PVAc graft copolymer with low grafting density was capable of self-folding in water into single-chain polymer nanoparticles (SCNPs) in a concentration range up to 10%. 34 The most intriguing aspect of these nanoparticles was the spontaneous formation by an intra-molecular self-assembly mechanism driven simply by the amphiphilic character of the copolymer, while most SCNPs described in the literature require the presence of either appropriate cross-linking agents, at specific points along the polymer segments, or the introduction of external stimuli like pH variation or UV irradiation to drive the self-folding process. 35 In the present work, we extended the investigation of the binary system PEG-g-PVAc/ water to polymer concentrations in the 10-90 wt% range, using rheological and scattering experiments that are fully in agreement with DPD simulations, demonstrating a progressive structuration of the SCNPs into hierarchically complex systems when increasing the polymer concentration.…”

“…Recent studies by our group highlighted that low-grafted PEG-g-PVAc can undergo self-folding into single-chain nanoparticles (SCNPs) when in water at concentrations below 10% w/w, and they are able to introduce hydrophobic molecules into the PVAc core. 34 The most interesting aspect here is that the SCNPs are formed spontaneously thanks to the amphiphilic properties of the copolymer, with no need for cross-linkers or external stimulibased strategies to drive the collapse and folding of one of the blocks. 35 Given the peculiar structures found in PEG-g-PVAc aqueous solutions at relatively low polymer concentrations, in the present work we expand the investigation in the 10-90% w/w concentration range and characterize the polymer's structural polymorphism by thermal, rheological and structural analyses, together with molecular calculations via Dissipative Particle Dynamics.…”

An Investigative Study on the Effect of Pre-Coating Polymer Solutions on the Fabrication of Low Cost Anti-Adhesive Release Paper

“…In addition to favorable surface roughness and smoothness tests, PEVA was shown to self-assemble into uniform layers of nanospheres of approximately 100 nm in diameter. Self-assembly has previously been observed for copolymers of PEVA and polyethylene glycol [30,33]. Based on the comparison of each of the pre-coating blends we can say that PEVA is the best option as a pre-coater blend to create RP from cheaper OPD paper.…”