Water soluble poly(ethylene oxide) functionalized norbornene polymers

Synthesis and characterization of poly(ethylene glycol) bottlebrush networks via ring‐opening metathesis polymerization

Herein it is reported how the overlap concentration (C*) can be used to overcome crosslinking due to diol impurities in commercial PEG, allowing for the synthesize of bottlebrush polymers with good control over molecular weight. Additionally, PEG-based bottlebrush networks are synthesized via ROMP, attaining high conversions with minimal sol fractions (<2%). The crystallinity and mechanical properties of these networks are then further altered by solvent swelling with phosphate buffer solution (PBS) and 1-ethyl-3-methylimidazolium ethyl sulfate/DCM cosolvents. The syntheses reported here highlight the potential of the bottlebrush network architecture for use in the rational design of new materials.

Recent development of brush polymers via polymerization of poly(ethylene glycol)-based macromonomers

Polymerization of poly(ethylene glycol)-based macromonomers is a facile and versatile synthetic method to generate well-defined brush polymers.

Surface-Attached Poly(oxanorbornene) Hydrogels with Antimicrobial and Protein-Repellent Moieties: The Quest for Simultaneous Dual Activity

By copolymerizing an amphiphilic oxanorbornene monomer bearing N- tert-butyloxycarbonyl (Boc) protected cationic groups with an oxanorbornene-functionalized poly(ethylene glycol) (PEG) macromonomer, bifunctional comb copolymers were obtained. Varying the comonomer ratios led to copolymers with PEG contents between 5⁻25 mol %. These polymers were simultaneously surface-immobilized on benzophenone-bearing substrates and cross-linked with pentaerythritoltetrakis(3-mercaptopropionate). They were then immersed into HCl to remove the Boc groups. The thus obtained surface-attached polymer hydrogels (called SMAMP*-co-PEG) were simultaneously antimicrobial and protein-repellent. Physical characterization data showed that the substrates used were homogeneously covered with the SMAMP*-co-PEG polymer, and that the PEG moieties tended to segregate to the polymer⁻air interface. Thus, with increasing PEG content, the interface became increasingly hydrophilic and protein-repellent, as demonstrated by a protein adhesion assay. With 25 mol % PEG, near-quantitative protein-adhesion was observed. The antimicrobial activity of the SMAMP*-co-PEG polymers originates from the electrostatic interaction of the cationic groups with the negatively charged cell envelope of the bacteria. However, the SMAMP*-co-PEG surfaces were only fully active against E. coli, while their activity against S. aureus was already compromised by as little as 5 mol % (18.8 mass %) PEG. The long PEG chains seem to prevent the close interaction of bacteria with the surface, and also might reduce the surface charge density.

Sugar-Functional Vinyl Addition Poly(norbornene)-Photopatternable Poly(norbornenyl gluconamide) Compositions Developed with Water

The norbornenyl gluconamide (NBGA) monomer can be polymerized by a number of palladium catalysts to give water-soluble, vinyl addition poly(NBGA). Depending on the catalyst used, the reaction conditions, and the chain-transfer additives employed, high-molecular-weight polymers can be obtained. These polymers can be thermally cross-linked at ca. 190 °C or at ca. 150 °C when the difunctional glutaraldehyde is added. A photopatternable composition is formed by the addition of a water-soluble diazide when the poly(NBGA) molecular weight is sufficiently high. After image-wise exposure, negative-tone patterns are revealed by water development. A detailed analysis of NBGA monomer structures by high-resolution nuclear magnetic resonance techniques including pure shift is reported showing that two diastereomers of each endo- and exo-isomer are formed from the reaction of norbornene methylamine and δ-gluconolactone.

Synthesis and characterization of high grafting density bottle-brush poly(oxa)norbornene-g-poly(ε-caprolactone)

The synthesis and the ring-opening metathesis polymerization of well-defined poly(ε-caprolactone)-based (oxa)norbornene macromonomers bearing two poly(ε-caprolactone) chains on the polymerizable entity are reported.

Unique nanotubes from polynorbornene derived graphene sheets

Graphene functionalized polynorbornene nanohybrids (PNAGRs) have been synthesized successfully and their interesting self-aggregation in organic solvent (tetrahydrofuran, THF) has been investigated thoroughly for the 1^st time in our present study.

Stimuli responsive nanocarrier for an effective delivery of multi-frontline tuberculosis drugs

We prepare stimuli responsive polymeric nanocarrier, RCP-2 to demonstrate the high drug content as well as controlled release in a systematic manner.

V, Shunmugam R. Reversible pH- and Lipid-Sensitive Vesicles from Amphiphilic Norbornene-Derived Thiobarbiturate Homopolymers

Synthesis of a new molecular architecture, an amphiphilic, norbornene-derived thiobarbiturate homopolymer (NTBH), by ring-opening metathesis polymerization (ROMP) and its characterization is discussed. The newly designed hompolymer shows a self-assembled vesicle formation in aqueous solution. Dynamic light scattering and critical aggregation concentration studies confirm the aggregate formation in solution while atomic force microscopy and transmission electron microscopy of the dried sample on the silicon substrate further confirm the vesicular morphologies of these amphiphilic homopolymers. Encapsulation studies of hydrophilic doxorubicin and hydrophobic Nile red suggest the reversible nature of the NTBH vesicles. Dye release studies in acidic and lipophilic environment demonstrate the stimuli-responsive nature of the novel systems. The results demonstrate that these self-assembled NTBH vesicles have great scope in the field of medicine as they symbolize themselves as promising carriers for the stimuli-triggered intracellular delivery of hydrophobic drugs.

Dual-functional ROMP-based betaines: effect of hydrophilicity and backbone structure on nonfouling properties

Foundational materials for nonfouling coatings were designed and synthesized from a series of novel dual-functional zwitterionic polymers, Poly[NRZI], which were easily obtained via ring-opening metathesis polymerization (ROMP) followed by a single step transformation of the cationic precursor, Poly[NR(+)], to the zwitterion, Poly[NRZI]. The resulting unique dual-functional structure contained the anion and the cation within the same repeat unit but on separate side chains, enabling the hydrophilicity of the system to be tuned at the repeat unit level. These dual-functional zwitterionic polymers were specifically designed to investigate the impact of structural changes, including the backbone, hydrophilicity, and charge, on the overall nonfouling properties. To evaluate the importance of backbone structure, and as a direct comparison to previously studied methacrylate-based betaines, norbornene-based carbo- and sulfobetaines (Poly[NCarboZI] and Poly[NSulfoZI]) as well as a methacrylate-based sulfobetaine (Poly[MASulfoZI]) were synthesized. These structures contain the anion-cation pairs on the same side chain. Nonfouling coatings were prepared from copolymers, composed of the zwitterionic/cationic precursor monomer and an ethoxysilane-containing monomer. The coatings were evaluated by using protein adsorption studies, which clearly indicated that the overall hydrophilicity has a major influence on the nonfouling character of the materials. The most hydrophilic coating, from the oligoethylene glycol (OEG)-containing dual-functional betaine, Poly[NOEGZI-co-NSi], showed the best resistance to nonspecific protein adsorption (Γ(FIB) = 0.039 ng/mm(2)). Both norbornene-based polymers systems, Poly[NSulfoZI] and Poly[NCarboZI], were more hydrophilic and thus more resistant to protein adsorption than the methacrylate-based Poly[MASulfoZI]. Comparing the protein resistance of the dual-functional zwitterionic coatings, Poly[NRZI-co-NSi], to that of their cationic counterparts, Poly[NR(+)-co-NSi], revealed the importance of screening electrostatic interactions. The adsorption of negatively charged proteins on zwitterionic coatings was significantly less, despite the fact that both coatings had similar wetting properties. These results demonstrate that the unique, tunable dual-functional zwitterionic polymers reported here can be used to make coatings that are highly efficient at resisting protein adsorption.

End-functionalized ROMP polymers for Biomedical Applications

We present two novel allyl-based terminating agents that can be used to end-functionalize living polymer chains obtained by ring-opening metathesis polymerization (ROMP) using Grubbs' third generation catalyst. Both terminating agents can be easily synthesized and yield ROMP polymers with stable, storable activated ester groups at the chain-end. These end-functionalized ROMP polymers are attractive building blocks for advanced polymeric materials, especially in the biomedical field. Dye-labeling and surface-coupling of antimicrobially active polymers using these end-groups were demonstrated.

Hydrophilic modifications of an amphiphilic polynorbornene and the effects on its hemolytic and antibacterial activity

Here we report the modification of an amphiphilic antibacterial polynorbornene, Poly3, via incorporation of hydrophilic, biocompatible groups. The sugar, zwitterionic, and polyethylene glycol based moieties were incorporated in varying ratios by copolymerization and postpolymerization techniques. Well-defined copolymers with molecular weights of 3 kDa and narrow polydispersity indices ranging from 1.08 to 1.15 were obtained. The effects of these modifications on the biological activity of these polymers were analyzed by determining their minimum inhibitory concentrations (MIC) and their hemolytic activities (HC50).