ABSTRACT

Methoxypoly(ethylene glycol)–oligo(aspartic acid) (MPEG–Asp_n-NH₂, n = 2–5) hybrid block copolymers were synthesized and used as stabilizers to prepare superparamagnetic Fe₃O₄ nanoparticles with magnetite as the inner core and and poly(ethylene glycol) as the hydrophilic outer shell. The aqueous dispersions of the nanoparticles were stable at pH 2–11 and in 1M NaCl solution, when repeat number, n, was 3 or more. Transmission electron microscopy showed that the nanoparticles, stabilized with MPEG–Asp₃-NH₂, were about 14 nm in diameter. Magnetic measurements indicated that MPEG–Asp₃-NH₂-coated iron oxide nanoparticles showed superparamagnetic behavior. Cell adhesion assay and in vitro cell viability/cytotoxicity studies showed that MPEG–Asp₃-NH₂-coated iron oxide nanoparticles had less effect on cell adhesion/viability and morphology, and less cytotoxicity compared with uncoated, poly (acrylic acid)-coated, and MPEG–poly(acrylic acid)-coated iron oxide nanoparticles. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006

To investigate the effects of multiple weak interactions on the binding of phenolic compounds by polymeric adsorbents, macroporous polystyrene (PS) resin and PS-based adsorbents with different hydrogen-bond acceptor atoms (PSCH₂(OCH₂CH₂)_nOCH₃, n = 0, 1, 2, and 3, denoted as PS-EG₀, PS-EG₁, PS-EG₂, and PS-EG₃) were prepared. The phenol adsorption strength order on these adsorbents was PS/PS-EG₀ < PS-EG₁ < PS-EG₂ < PS-EG₃, indicating that the adsorption on PS and PS-EG₀ was driven by hydrophobic and π–π interactions, and the adsorption on PS-EG₁, PS-EG₂, and PS-EG₃ was driven by a hydrogen bond in addition to hydrophobic and π–π interactions. PS-EG₂ may adsorb a second phenol molecule on each binding site and PS-EG₃ may adsorb second and third ones. The adsorption strength of resorcinol increased in the order of PS, PS-EG₁, and PS-EG₂, indicating that the adsorption was driven by 0, 1, and 2 hydrogen bonds in addition to hydrophobic and π–π interactions. Similarly, the adsorption of phloroglucinol on PS, PS-EG₁, PS-EG₂, and PS-EG₃ was driven by 0, 1, 2, and 3 hydrogen bonds in addition to hydrophobic and π–π interactions because the adsorption strength increased in this order. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4652–4658, 2006

Summary: Solketal acrylate (SA) was homopolymerized by atom transfer radical polymerization (ATRP) using CuBr/N,N,N′,N″,N″-pentamethyldiethylenetriamine as the catalyst and cyclohexanone as the solvent with controlled molecular weights and low polydispersities. The prepared bromine-terminated homopolymers, PSA, were used as macroinitiators to initiate polymerization of tert-butyl acrylate (tBA) under similar ATRP conditions to produce diblock copolymers, PSA-b-PtBA, with controlled molecular weights and low polydispersities. ATRP of SA using bromine-terminated PtBA as the macroinitiator was also carried out and diblock copolymers, PtBA-b-PSA, were obtained. The PSA block was selectively hydrolyzed by stirring for 3 h in 6 N HCl/THF (1/9, v/v) at room temperature to form a poly(glycerol monoacrylate) block. Both blocks of PSA and PtBA were hydrolyzed by stirring in anhydrous trifluoroacetic acid (TFA)/dichloromethane for 4 h, then adding water to the system and stirring for another 3 h to form corresponding diblock copolymers of glycerol monoacrylate and acrylic acid.