Amphiphilic quasi-block copolymers and their self-assembled nanoparticles via thermally induced interfacial absorption in miniemulsion polymerization

Abstract

A facile and nontoxic strategy for the preparation of amphiphilic quasi-block copolymers and nanoparticles has been developed utilizing miniemulsion polymerization. By volume phase transition behavior of poly(Nisopropyl acrylamide) (PNIPAM) and thermally induced interfacial absorption, amphiphilic copolymer was generated, which can self-assemble into core-shell nanoparticles in situ. Stearyl methacrylate (SMA) was used as hydrophobic monomer and to form crystalline core, because it has pendent long alkyl side chain and can form crystalline domain to synthesize comb-like polymers. A volatile organic cosolvent was used to enhance the formation process and particles size, and the formation mechanism was investigated. Impacts of cosolvent concentration, monomer feed ratio and polymerization temperature on the morphology and thermal characteristics of particles were studied by DLS, TEM and DSC. 1 H NMR, 13 C NMR and GPC were carried out to analyze the chemical structure and composition of copolymers.The triads sequence and average block length are analyzed to determine the sequence distribution of copolymers. Volume phase transition temperature (VPTT) of PNIPAM copolymer was first increased to nearly 40 C with hydrophobic monomer rather than hydrophilic monomer. In addition, hydrophilic property of copolymer and the drug release behavior were studied to understand further applications. These amphiphilic quasi-block copolymers show great potential in the controlled delivery system for drugs.

A novel drug loading and release from a thermoresponsive hydrogel formedin situemulsion polymerization

“…NIPAM (J&K Chemical, America) was purified by recrystallizing three times in n ‐hexane and then dried at 45 °C in a vacuum oven 2b. 2,2′‐Azobis (isobutyronitrile) (AIBN, J&K Chemical, China) was recrystallized from ethanol and then dried in vacuum at 45 °C.…”

“…In general, nanoparticles, nanocapsules, and hydrogels are suitable vehicles to overcome these limitations . In particular, thermal‐sensitive core‐shell nanoparticles and capsules can open access to load drugs in their hydrophobic core and release them when the temperature is higher than their lower critical solution temperature (LCST) . Hydrogels are formed with three‐dimensional self‐assembled networks and can retain large amounts of water in them.…”

Controlled co‐delivery of hydrophilic and hydrophobic drugs from thermosensitive and crystallizable copolymer nanoparticles

“…The size and morphology of nanoparticles formed by amphiphilic block copolymers can be varied by changing the composition, molecular weight, and block length ratios of hydrophobic and hydrophilic segments on the polymer chains. 14 Poly(N-isopropyl acrylamide) (PNIPAM) formed the hydrophilic shell of nanoparticles, and its volume phase transition behavior could improve temporal control. Most present research on drug delivery systems are applied to load and delivery a single drug, which often could not satisfy the demands of combination therapy.…”

“…In our previous work, we developed a facile and nontoxic strategy for preparing amphiphilic block copolymers and self-assembled core-shell nanoparticles via thermally induced interfacial absorption in miniemulsion polymerization. 14 Poly(N-isopropyl acrylamide) (PNIPAM) formed the hydrophilic shell of nanoparticles, and its volume phase transition behavior could improve temporal control. Stearyl methacrylate (SMA) was used as hydrophobic monomer to synthesize comblike polymers and form nanocrystalline core, since it has pendent long alkyl side chain to form crystalline domain.…”