The regioselective functionalization of both model and commercial polypropylenes of varying tacticity has been conducted by a rhodium-catalyzed functionalization of the methyl C-H bonds of the polymer with diboron reagents. Rhodium-catalyzed borylation of the polypropylenes, followed by oxidation of the boron-containing material, produced polymers containing 0.2-1.5% hydroxymethyl side chains. Both the number-average molecular weights and molecular weight distributions of the polypropylenes were essentially unchanged after the catalytic and oxidative functionalization process. The efficiency of the borylation process was affected by the molecular weight of the polymer, the steric hindrance around the methyl groups, and the ratio of the diboron reagent to the monomer repeat unit. The hydroxylated derivative of the commercial isotactic polypropylene was used as macroinitiator for the aluminum-mediated ring-opening polymerization of epsilon-caprolactone to prepare polypropylene-graft-polycaprolactone. This graft copolymer was an effective compatibilizer for melt blends of polypropylene and polycaprolactone.

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Antisense technology holds tremendous potential in the research and clinical settings. However, successful delivery of antisense oligodeoxynucleotides (ODNs) to the intracellular site of action requires the passage of many barriers, including survival against extracellular serum nucleases and escape from endolysosomal degradation. Previous work has shown that the effectiveness of antisense delivery by the cationic liposome, dioleoyl-3-trimethylammonium-propane (DOTAP), is enhanced substantially by the incorporation of a pH-sensitive polymer, poly (propylacrylic acid) (PPAA), in serum-free media. To improve this system for application in serum-containing media conditions, PPAA was modified in this work by grafting onto it either poly(ethylene oxide) (PEO) or a more hydrophobic analog, poly (oxyalkylene amine), known as Jeffamine. The ternary formulation of DOTAP/ODN/PPAA-g-Jeffamine resulted in 8-fold increased uptake of fluorescently-labeled ODNs compared to DOTAP/ODN/PPAA and ∼80% silencing of green fluorescent protein (GFP) expression in CHO-d1EGFP cells treated in the presence of 10% FBS-containing media. In contrast, the carrier systems that contained PPAA or PPAA-g-PEO failed to display any significant antisense activity in the presence of serum, even though all of the delivery systems displayed moderate to high levels of antisense activity in serum-free conditions. The results reveal that the carrier system with the Jeffamine graft copolymer effectively mediates specific gene silencing in the presence of serum, while the system with the PEO graft copolymer fails to do so. While the pH-dependent lytic functionality of PPAA was found to be lost upon grafting with PEO or Jeffamine, the hydrophobicity of the latter was sufficient to mediate cellular internalization and endosomal escape. Thus, the PPAA-g-Jeffamine copolymers hold substantial promise as agents for controlled therapeutic delivery of antisense oligonucleotides.

This article explores current challenges in the use of automated parallel synthesizers in polymeric materials research. Four types of polymerizations were investigated: carbodiimide‐mediated polyesterification, diphenol phosgenation, free radical, and reversible addition‐fragmentation chain‐transfer (RAFT). Synthetic challenges of condensation polymerization, such as liquid and solid dispensing accuracy, dropwise addition, and toxic chemical handling, were successfully met using the automated synthesizer. Both solid and liquid dosing of the diphenol and diacid were successful for polyarylate synthesis. The high precision of liquid dispensing made it possible to achieve stoichiometric balance using reagent stock solutions. For all reactions, molecular weights and their reproducibility were comparable to those obtained with manual synthesis. For RAFT polymerizations, solvent and mol ratio of chain transfer reagent to initiator were successfully optimized on the automated synthesizer and a library of over 60 polymethacrylate copolymer compositions was generated. Considerable savings in time relative to manual methods were achieved when generating polymer libraries (e.g., 4.5× faster for 96 polymethacrylates and 20× faster for 45 for polycarbonates). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 49–58, 2009