Journal of Polymer Science Part A: Polymer Chemistry

Electronic coupling via the cardo structure in polyfluorene is investigated by Hyeonuk Yeo, Kazuo Tanaka, and Yoshiki Chujo on page 4433. The electronic states of the main chain of polyfluorene can be preserved from the introduction of electronic withdrawing and/or donating groups by the cardo structure. Pure blue emissions can be obtained from these polymers. Moreover, this preservation effect by the cardo structure is perceived even in the film state after annealing. These results suggest the possibility that the cardo polyfluorene is promising as a scaffold for assembling functional molecules based on preprogrammed positions to obtain desired functions.

An easy encapsulation technique of carbon nanotubes within a polymer sheath of tunable thickness is presented on page 4403 by Weiheng Zhong, Jules Nguendia Zeuna, and Jerome P. Claverie. The image shows various single-wall and multi-wall carbon nanotubes encapsulated in a polystyrene or poly(methyl methacrylate) layer. This method, which does not require any covalent modification of the carbon nanotube, or any organic solvent, could easily be implemented on a large scale. It is expected that the encapsulated nanotubes exhibit greater compatibility with polymeric matrices, thus facilitating the preparation of nanotube-polymer nanocomposites.

Nowadays, durable esthetic direct resin-based filling composites in combination with efficient enamel-dentin adhesives play an important role in modern dentistry. Thereby, the surface of the cavity is etched and primed with a self-etching enamel-dentin adhesive. After filling the cavity with the composite and photocuring (see picture), a highly esthetic tooth shaded composite restoration is created. The article describes the continuous improvement of the properties of the direct restorative materials by the use of new tailor-made functionalized monomers and cross-linkers as well as new additives and photoinitiators.

Using a RAFT polymerization process, uniform polymer coats are physically adsorbed onto the surface of a SWNT and MWNT.

A series of triblock copolymers having self-complementary hydrogen-bonding units have been synthesized through RAFT polymerization of the methacrylate monomer containing bis-dendritic benzamide group. The triblock copolymers showed the formation of polymeric nanoparticles and aggregation behavior through intramolecular and intermolecular hydrogen bondings. Well-ordered hexagonal structures were prepared by “Breath Figure” technique.

A novel approach is developed for the preparation of a unique class of core/shell nanoparticles using self-assembled polymer micelle as a reactive nanoreactor. Such core/shell nanoparticles are composed of optically active helical-substituted polyacetylene (forming the core) and thermosensitive poly(N-isopropylacrylamide) (forming the shell). The nanoparticles simultaneously exhibit remarkable optical activity and thermosensitivity.

Graphene–polymer composites of positive-charged poly(dimethyl aminoethyl acrylate), negative-charged poly(acrylic acid) and neutral polystyrene were prepared by “graft from” methodology using reversible addition fragmentation chain transfer (RAFT) polymerization via a pyrene functional RAFT agent modified graphene precursor. Fluorescence spectroscopy evidenced that the RAFT agent was attached on the graphene basal planes by π–π stacking interactions, which is strong enough for anti-dissociation in the polymerization mixture up to 80°C.

The electronic coupling via the cardo structure in polyfluorene was investigated. It was found that the electronic states of polyfluorene can be preserved from the introduction of electronic withdrawing and/or donating groups by the cardo structure. The pure blue emissions can be obtained from these polymers.

Poly[(oligoethylene glycol) methyl ether acrylate] [poly(OEGA)] brushes on gold substrate were synthesized by RAFT-mediated polymerization. Poly(OEGA) chains with the terminal carboxylic acid groups introduced by chain transfer agent were functionalized with amine-functionalized biotin units to provide selective attachment points for streptavidin. The successful immobilization of streptavidin molecules on the polymer brushes was observed by fluorescence microscopy.

PNIPAM polymer chains were grown in situ from the surface of “TRIS”-modified graphene oxide sheets via SET–LRP under mild conditions to afford polymer/graphene oxide hybrid materials with excellent dispersibility and thermoresponsibility.

A new approach for vinyl polymerization of norbornene (NB) by using nickel precursors bearing salicylaldimine ligands is presented. These novel catalytic systems catalyze the polymerization of NB with very high activity (78,000 kg of polymer/mol of catalyst × h). The high activity appears particularly attractive considering that these precursors areeconomically and ecofriendly prepared in situ with simple synthetic procedure.

This study elucidates the influence of the initiator structure formed using diazonium chemistry on the kinetics of the surface-initiated atom transfer radical polymerization (SI-ATRP) of methyl methacrylate in acetone using the quartz crystal microbalance technique with dissipation (QCM-D). The QCM-D measurements reveal several new interesting insights. For the first time a direct detection of the formation of a precursor complex between the surface immobilized initiator and the catalyst is shown. Moreover, QCM data allow for the discrimination of mushroom, semi-dilute, and concentrated brush regimes.

Diels–Alder click reaction is used for the preparation of various types of aliphatic polycarbonates (PCs). The novel anthracene-functionalized cyclic carbonate monomer, anthracen-9-ylmethyl 5-methyl-2-oxo-1,3-dioxane-5-carboxylate (2), was prepared and used for the following ROP affording the synthesis of the PC with pendant anthracene groups (PC-anthracene) using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)/1-(3,5-bis(trifloromethyl)phenyl)-3-cyclohexylthiourea (TU) as catalyst and benzyl alcohol as initiator in CH₂Cl₂ at room temperature. Subsequently, the PC-anthracene was clicked with a linear α-furan protected-maleimide terminated-poly(methyl methacrylate) (PMMA-MI), or –poly(ethylene glycol) (PEG-MI), or a mixture of PMMA-MI and PEG-MI to yield well-defined PC graft or hetero graft copolymers, PC-g-PMMA or PC-g-PEG, or PC-g-(PMMA)-co-PC-g-(PEG), respectively using Diels-Alder click reaction in toluene at 110°C.

Chitosan-based nanoparticles were prepared by interpolymer polyelectrolyte complexation with a poly(acrylic acid) homopolymer and with a polystyrene-block-poly(acrylic acid) diblock copolymer, respectively. Parameters such as the charge ratio between the mixed partners, pH, and ionic strength were thoroughly studied by dynamic light scattering and led to the identification of domains of stability for the accordingly obtained nanoparticles.

Synthesis and dynamics of supramolecular poly(isobutylene) networks bearing statistically distributed hydrogen-bonding moieties (a weak pyridinium/pyridine interaction and a (stronger) 2,6-diaminotriazine/thymine interaction) are reported, aiming at the understanding of network formation in self-healing materials. In the melt state, a clear difference in the (weaker) pyridinium/pyridine interaction (effective cluster lifetime τ_b * ∼ 1 s) to the 2,6- (stronger) diamintriazine/thymine interaction (τ_b * ∼ 100 s) is observed now enabling the future design of self-healing rubbery supramolecular polymers.

Conversion of reactive glycidyl groups as determined from the area of DSC measured exotherms versus time for different isothermal cure temperatures of a phosophotungstate-epoxy nanocomposite with a phosophotungstate volume fraction of 0.05. The solid lines are best fits to an autocatalytic rate expression.

The synthesis of poly(2-ethyl-2-oxazoline)-block-poly(2-H-2-oxazoline) (PEtOx-b-PHOx) and the subsequent selective hydrolysis to PEtOx-b-LPEI is described. Therefore, an improved and straightforward synthesis of the monomer HOx was developed, and its polymerization kinetics were investigated. The polymers were characterized in detail by ¹H NMR spectroscopy and MALDI-TOF-MS.

A new stereoregular 2-amino-glycan composed of a mannosamine residue was prepared by ring-opening polymerization of anhydro sugars. Two different monomers, 1,6-anhydro-2-azido-mannose derivative and 1,6-anhydro-2-(N, N-dibenzylamino)-mannose derivative, were synthesized and polymerized. Although the 2-azido monomer gave merely oligomers, the 2-(protected amino) monomer was promptly polymerized into high polymers with 1,6-α stereoregularity. The differences of each polymerizability from those of the corresponding glucose homologs were discussed from the view point of configuration of the substituent on C2.

A novel amphiphilic poly(ethylene glycol)-block-poly(γ-cholesterol-L-glutamate) (mPEG-PCHLG) diblock copolymer has been synthesized and characterized. The mPEG-PCHLG copolymers could aggregate into nanoparticles with PCHLG blocks as the hydrophobic core and PEG blocks as the hydrophilic shell and the nanoparticles have shown good physicochemical properties and low toxicity.

Stereocomplex of poly(L-lactide) and poly(D-lactide) containing imidazolium ionic liquid end-groups (PLA-IL) precipitates from 1,4-dioxane solution in the form of monodisperse, perfectly spherical microspheres. Such behavior of PLA-IL, not observed for polymers containing other end-groups such as HO, C₄H₉O, CF₃O, or C₄F₇H₂O groups, can be attributed to the presence of strongly interacting end-groups derived from ionic liquid.

An epoxide-containing pyrene derivative is designed, synthesized, and used as a reactive noncovalent dispersant for improving dispersion and integration of single-walled carbon nanotubes in epoxy composites.

For the purpose of developing an efficient blue-emitting polymer used in organic light-emitting diodes (OLEDs), N-arylcarbazole-2,7-diyl unit was copolycondensed with 9,9-dioctylfluorene-2,7-diyl unit in random and alternating orders, respectively, to add electron injection ability in addition to hole-injection and -transport ability of poly(carbazole-2,7-diyl)s. An OLED device embedded with the random copolycondensate worked efficiently under operating voltages lower than 7 V, whose performance was notably higher compared to other devices embedded with the alternating copolycondensate and each homopolymer.

A series of well-defined organic–inorganic hybrid block copolymers were synthesized by atom transfer radical polymerization. The inorganic block consisted of a ladder-like structured polyphenylsilsesquioxane and was utilized as polymeric macroinitiator for the polymerization for hard and soft organic polymers, polystyrene, and poly(n-butyl acrylate). Synthesized hybrid block copolymers exhibited unique thermal properties.

Highly effective cationic addition polymerization of 1,4-dioxene, a six-membered cyclic olefin with two oxygen atoms adjacent to the double bond, was performed using a simple metal halide catalyst system in dichloromethane. The propagating reaction was well controlled when the reaction was conducted using GaCl₃ with an isobutyl vinyl ether–HCl adduct as a cationogen at –78°C to give polymers with predetermined molecular weights and relatively narrow molecular weight distributions. The obtained poly(1,4-dioxene) exhibited a very high glass transition temperature of 217°C and unique solubility.

An acid-sensitive PEG-b-PtBA-b-P(HEMA-CAD) prodrug with high drug loading content reaching up to 38% was synthesized, which can deliver drugs through either physical embedding method or covalently linkage method.