Note in 2012

The cloud point was determined for aqueous solutions of two poly(N-isopropylacrylamide) samples, one having a hydrophobic nonionic chain-end group (M sample) and the other having a hydrophilic anionic chain-end group (R sample), with an addition of two kinds of surfactants, anionic sodium n-dodecyl sulfate (SDS) or cationic n-dodecyltrimethylammonium chloride (DTAC). It is found that behavior of the cloud point as a function of the concentration c_s of the surfactants largely depends on the kinds of chain-end group and surfactant.

A highly bulky methacrylate, tris(trimethylsilyl)silyl or supersilyl methacrylate, was polymerized quantitatively with 9-fluorenyllithium in the presence of (−)-sparteine as a chiral ligand in toluene at −78 °C to give insoluble polymers. The obtained polymers exhibited high isotacticity (mm>99%) and chirality, which was confirmed by diffuse reflectance circular dichroism spectroscopy. Thus, the bulky silyl methacrylate undergoes asymmetric anionic polymerization with the chiral initiating systems via formation of a prevailing one-handed helical conformation.

A series of two-dimensional conjugated polymers (P1–P4) based on benzo[1,2-b:4,5-b’]dithiophene donor unit and thiophene unit modified by pendant acceptor groups were synthesized. P1–P4 possess good solubility, thermal stability, tunable optical properties and low HOMO energy levels. Bulk heterojunction polymer solar cells based on P2 exhibit a power conversion efficiency of 1.89% and an impressively high V_oc of 0.93 V.

Noncovalent functionalization of multi-walled boron nitride nanotubes (BNNTs) was achieved through water-soluble synthetic polymers wrapping. This led to the excellent disentanglement and dispersion of BNNTs in an aqueous phase. Various spectroscopic techniques revealed that π-π stacking interactions played the key role for the polymer-functionalization of BNNT. To show a prospective application of polymer-functionalized BNNTs in surface engineering fields, the disentangled BNNTs were used as the raw/starting materials for the creation of superhydrophobic surfaces.

Triblock copolymers comprising multifunctional poly(oxyethylene) (PEO) central block with various regularly distributed side functionalities and poly(D,L-lactide) outer blocks were synthesized. In the first step, an acetal-linked, in-chain multifunctional PEO was used as a macroinitiator for the metal-free controlled ring-opening polymerization of D,L-lactide. The amphiphilic biodegradable triblock copolymers provide a platform for further multifunctionalization through efficient quaternization and ‘click’ reactions. Thus, zwitterionic, fluorophilic, alkyne and alkyl pendant functionalities were introduced into the central PEO-block.

The glycosaminoglycan model polymers with poly-γ-glutamate backbone were synthesized by conjugation with a p-aminophenyl 6-sulfo-β-GlcNAc or taurine. Poly-γ-glutamate with 6-sulfo-β-GlcNAc exhibited the inhibition activity on aggregation of Alzheimer amyloid beta peptide(1–40). On the other hand, the polymer with taurine didn't show the inhibitory activity on aggregation of amyloid beta peptide and rather accelerated the aggregation.

Chemical oxidative polymerization (COP) of 3-hexylthiophene in polar solvents, such as CH₃CN and CH₂Cl₂, smoothly proceeded at temperatures below 0 °C to afford regio-controlled poly(3-hexylthiophene-2,5-diyl) (P3HexTh) with a head-to-tail (HT) content of higher than 80%. Use of CH₃CN at −40 °C gave P3HexTh with 83% HT content, M_n (number-average molecular weight) of 42 000, and a relatively narrow polydispersity of 1.6. Obtained P3HexTh formed an ordered structure in solid, and NOBF₄-treated film of P3HexTh with the HT content of 83% showed electrical conductivity of 3.0 S cm⁻¹.

Monodisperse polystyrene particles were prepared by enzymatic emulsifier-free emulsion polymerization using a horseradish peroxidase (HRP)/H₂O₂/β-diketone system in water. The resultant polymer particles were stabilized by the β-diketone moieties located at the surface of the particle. Enzymatic emulsifier-free emulsion polymerization might offer a practical method for the preparation of polymer particles under mild enzymatic conditions (that is, room temperature and surfactant-free).

Well-defined multifunctional diblock copolymers with terminal functional groups were synthesized by the combination of cationic ring opening polymerization (CROP) and reversible addition-fragmentation chain transfer radical (RAFT) polymerization. Poly(ɛ-caprolactone) (PCL)-based biodegradable macro-RAFT agent was synthesized by CROP of CL from hydroxylated RAFT agents. Subsequently, thermoresponsive poly(N-isopropylacrylamide) derivative was propagated using the biodegradable macro-RAFT agent. Obtained polymers highly preserved terminal dithiobenzoate groups, which were easily converted to thiol groups by aminolysis. Therefore, biotin-maleimide was able to be reacted with terminal group. The present method was promising for preparing block copolymer-based multi-functional polymeric micelles.

The local structure of the acidic-treated model peptides,(E)₈GGLGGQGAG(A)₆GGAGQGGYGG, derived from the consensus sequence of Nephila clavipes fibroin major ampullate spidroin 1 was determined using two-dimensional proton-driven spin-diffusion solid-state NMR under off-magic-angle spinning coupled with ¹³C isotope double labeling of specific residues. We observed a positional dependence on the torsion angles of Ala residues in the β sheet. Torsion angle of the Ala residue at the center of poly-Ala domain concentrates around at (ϕ, ψ) = (−150°, 150°), while that of its periphery is distorted and more distributed.

Mono- and bis-stannylation at the chain ends of regioregular poly(3-hexylthiophene) (P3HT) were conducted by post-functionalization of P3HT synthesized through Ni-catalyzed Grignard metathesis polymerization. Lithiation of P3HT with s-BuLi and subsequent stannylation with Me₃SnCl led to the formation of bis-stannylated P3HT. The highest conversion of 81% was achieved with the additive N,N,N′,N′-tetramethylethylenediamine (TMEDA), which could enhance the stability of the lithiated compound. On the other hand, mono-stannylated P3HT was synthesized without contamination by bis-stannylated P3HT through successive reactions with a Grignard reagent and Me₃SnCl.

Microscopic behaviors of explicit water molecules on biocompatible zwitterionic self-assembled monolayer (SAM) surfaces were investigated by molecular dynamics simulations. The orientational distribution of water molecules near the surfaces was evaluated to analyze its structural properties. Consequently, water molecules on the zwitterionic SAMs are randomly oriented. In contrast, those near the surface of poly(vinyl alcohol) are highly oriented, resulting from the structured hydrogen bonding network. Microscopic properties of water molecules on the interfaces would have a key role in the suppression of protein adsorption for zwitterionic biomaterials.

A novel Se-containing heterocycle 4,6-Bis(4′-hexylthiophen-2′-yl)thieno[3,4-c][1,2,5]selenadiazole (DTTSe) was synthesized for the first time and used as a new acceptor unit for developing donor−acceptor-conjugated copolymers.

In this study, we developed a method to prepare (R)-3-hydroxybutyryl-CoA for enzymatic cell-free polymerization, using crotonic anhydride as a starting material.

We have prepared silver nanoparticles from a solution of AgNO₃ and copolymers containing acryloylmorpholine and n-isopropylacrylamide (NIPAM) blocks by stirring the solution, and have examined the thermoresponsive properties of the associated plasmon peaks. The hydrosols prepared from the copolymer caused a red shift of the plasmon absorption with an increase in the temperature because the degree of nanoparticle protection was reduced owing to the shrinkage of the NIPAM blocks at 40 °C.

Biologically identified peptides that bind to the surfaces of isotactic poly(methyl methacrylate) (PMMA), syndiotactic PMMA, and their assembled stereocomplex films were used as noncovalent surface modifiers. Each peptide was biotinylated and immobilized onto the PMMA films to function as a linker for the subsequent immobilization of streptavidin. We demonstrated that the PMMA species had a great impact on the peptides' abilities to functionally modify the film surfaces.