title: Acid-Labile Amphiphilic PEO-b-PPO-b-PEO Copolymers: Degradable Poloxamer Analogs.
abstract: Poly ((ethylene oxide)-b-(propylene oxide)-b-(ethylene oxide)) triblock copolymers commonly known as poloxamers or Pluronics constitute an important class of nonionic, biocompatible surfactants. Here, a method is reported to incorporate two acid-labile acetal moieties in the backbone of poloxamers to generate acid-cleavable nonionic surfactants. Poly(propylene oxide) is functionalized by means of an acetate-protected vinyl ether to introduce acetal units. Three cleavable PEO-PPO-PEO triblock copolymers (Mn,total = 6600, 8000, 9150 g·mol(-1) ; Mn,PEO = 2200, 3600, 4750 g·mol(-1) ) have been synthesized using anionic ring-opening polymerization. The amphiphilic copolymers exhibit narrow molecular weight distributions (Ð = 1.06-1.08). Surface tension measurements reveal surface-active behavior in aqueous solution comparable to established noncleavable poloxamers. Complete hydrolysis of the labile junctions after acidic treatment is verified by size exclusion chromatography. The block copolymers have been employed as surfactants in a miniemulsion polymerization to generate polystyrene (PS) nanoparticles with mean diameters of ≈200 nm and narrow size distribution, as determined by dynamic light scattering and scanning electron microscopy. Acid-triggered precipitation facilitates removal of surfactant fragments from the nanoparticles, which simplifies purification and enables nanoparticle precipitation "on demand."
authors.affiliation: Institute of Organic Chemistry, Johannes Gutenberg-University, Duesbergweg 10-14, 55128, Mainz, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Worm
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
authors.forename: Biao
authors.initials: B
authors.lastname: Kang
authors.affiliation: Institute of Organic Chemistry, Johannes Gutenberg-University, Duesbergweg 10-14, 55128, Mainz, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Dingels
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
authors.forename: Frederik R
authors.initials: FR
authors.lastname: Wurm
authors.affiliation: Institute of Organic Chemistry, Johannes Gutenberg-University, Duesbergweg 10-14, 55128, Mainz, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Frey
mesh_terms: D063566:Biodegradable Plastics / Q000138:chemical synthesis* / Q000737:chemistry*; D006868:Hydrolysis; D011092:Polyethylene Glycols / Q000138:chemical synthesis* / Q000737:chemistry*; D013500:Surface Tension
chemical_list: D063566:Biodegradable Plastics; D011092:Polyethylene Glycols
keywords: acid-cleavable; amphiphilic copolymers; miniemulsions; nonionic surfactants; poloxamers