Journal of Polymer Science Part A: Polymer Chemistry

The image shows a representative one-handed helical structure of poly(naphthalenecarboxamide) obtained by DFT calculation. On page 739, Koichiro Mikami and Tsutomu Yokozawa present the synthesis and chiral amplification of a helical aromatic polyamide, poly(naphthalenecarboxamide), with alkyl side chains. The helical polyamide is synthesized by means of chain-growth condensation polymerization. The folding of the polymer is exemplified using UV and CD spectroscopy. The copolymer of monomers having a chiral alkyl side chain and an achiral alkyl side chain shows a significant chiral amplification on the basis of the sergeants and soldiers principle in a hydrophobic environment even with only a tiny incorporation of chiral units.

The combination of UV curing and a new phosphonium borate salt has enabled the production of tough polyelectrolyte films in a single step, as described by B. M. Berven, P. J. Ragogna, et al. on page 499. A series of new polymerizable anions Na[BPh_xSty_4-x], x = 0–3, are prepared in high yields with 1–4 para-vinylphenyl units incorporated onto the boron atom, and these borates have the potential to be paired with a wide variety of cationic units. Pairing with a polymerizable phosphonium cation gives a series of organic salts that are directly polymerized by UV curing, affording highly crosslinked polyelectrolyte films that do not require the usual substrate pre-treatment (glass) or instillation of an anchoring layer. The mechanical properties of the polymeric materials could also be tailored by the anion functionality, as demonstrated by the increased scratch resistance as the crosslink density increased.

Highly reactive polyisobutylene (HR PIB) can be successfully prepared by cationic polymerizaion at room temperature using special initiating and catalyst systems like modified Lewis acids and metal complexes associated with weakly coordinating anions. Successful systems allow chain transfer to be regulated and protic activity to be reduced.

The radical thiol-ene reaction is used to modify the backbone of a common ROMP-prepared homopolymer. Hydrothiolation is successful in most instances in facilitating the ready introduction of a range of functionality including OH, pyrrole, alkyl, ester, and POSS species while still retaining the well-defined characteristics of the parent polymer.

A novel bifunctional cobalt-porphyrin catalyst which contains a Lewis acidic metal center and a quaternary ammonium salt unit in a molecule has been developed. This new catalyst system exhibits superior copolymerization activity in comparison to a traditional binary system.

Tough polyelectrolyte coatings have been produced in a single step by UV-curing novel phosphonium-borate monomers. The new tetrakis(styryl)borate anion enables high crosslink density upon rapid photopolymerization. The full series of borates NaBPh_xSty_4−x, x = 0−3, have also been prepared and incorporated into the phosphonium borate salt monomers. As the number of styrene groups in the monomer increases, the polymer films become more mechanically resilient. Analysis by nanoindentation showed an increase in the film hardness while scratch tests showed an increased scratch resistance of the polyelectrolyte surface.

A high-temperature reactive solution blending approach was successfully used to covalently incorporate fluorescent chromophores such as perylenebisimide (PBI) oligo(p-phenylene vinylene) (OPV) into the backbone of an engineering thermoplastic polyester [poly(1,4-cyclohexylenedimethylene-1,4-cyclohexanedicarboxylate)] (PCCD). The chemical incorporation of these chromophores into PCCD was confirmed by carrying out the melt condensation using 1,4-cyclohexanedimethanol and 1,4-dimethylcyclohexane dicarboxylate with varying mole ratios of terminal hydroxyl-functionalized PBI and OPV derivatives. The advantages of this solution blending approach over melt condensation were its ease of synthesis and high incorporation of the desired chromophore (>30 mol % of PBI) with thin film processability.

Aliphatic polyurethanes could be obtained in high yields via a non-isocyanate method based on the self-polycondensation of dihydroxyurethanes obtained by the reaction of diamines and ethylene carbonate. Two-step polycondensation, consisting of the polycondensation under a N₂ atmosphere followed by that under reduced pressure, was effective. The resulting polyurethane having hydroxyl groups at both of the end groups was converted to polyurethane methacrylate that served as a crosslinker for radical polymerization of methyl acrylate.

This study deals with control of the molecular weight of polyvinyl acetate (PVAc) emulsion by iodine-transfer radical polymerization and RAFT polymerization. Emulsion polymerization using ethyl iodoacetate more closely approximates the theoretical molecular weights than does the free radical polymerization. On the other hand, RAFT polymerizations reveal that the dithiocarbamate controls the polymer molecular weight more than xanthate under the same condition. Seed-emulsion polymerization is also performed using the chiral polyester seed to fabricate emulsions with core-shell structures.

Suspension cationic polymerization of IBVE coinitiated by AlPW₁₂O₄₀ in aqueous medium could be achieved to synthesize poly(IBVE) with m diad of around 60% in the presence of a sufficient amount of HCl. The cationic polymerization of IBVE in aqueous medium in the presence of HCl proceeded extremely rapidly even at very low concentration of AlPW₁₂O₄₀. All the poly(IBVE) growing chains were terminated by H₂O and further transferred to aldehyde and alkenal terminal groups.

Two series of mesogen-jacketed liquid crystalline polymers, PF3Cm and PC4Cm, were synthesized. Wide-angle X-ray diffraction measurements show that the mesophase structures of these polymers are dependent on the number of the carbon atoms in the fluorocarbon substituent and the property of the other terminal substituent. Polymers with fluorocarbon substituents enter into columnar nematic phases when m ≥ 4, whereas the polymer PF3C1 exhibits no liquid crystallinity. For polymers with butyl substituents, columnar nematic phases form when the number of carbon atoms at both ends of the side chain is not equal at high temperatures and disappear after the polymers are cooled to ambient temperature. However, when the polymer has the same number of carbon atoms at both ends of the side chain, a hexagonal columnar phase develops, and this phase remains after the polymer is cooled.

An original strategy to construct a new donor–acceptor-integrated structure has been developed. Extremely short π–π stacking distance of 0.32 nm has been achieved for PCBTT in solid states. A broadened light harvesting of the resulting copolymer coversthe solar flux from 300 to 750 nm with a low-lying HOMO energy level of −5.30eV.

This work presents novel polyimides (PIs) derived from 1R,2S,4S,5R-cyclohexanetetracarboxylic dianhydride (H″-PMDA). In particular, the PI system derived from H″-PMDA and 4,4′-oxydianiline simultaneously achieved excellent optical transparency, a very high T_g exceeding 300 °C, high toughness (elongation at break > 70%), and good solution processability as plotted within the target area in this figure. The results suggest that the H″-PMDA-based PI systems can be promising candidates for novel high-temperature plastic substrate materials in electronic paper displays.

The polymerization of propylene by C₁-symmetric dibenzyl zirconium complexes of nonsymmetric Salan ligands that feature a halo-substituted phenolate ring and a bulky alkyl-substituted phenolate ring is described for the first time. Polypropylene of average isotacticity and enantiomorphic site control signature typical of C₂-symmetric catalysts imply a facile polymeryl site epimerization and propylene insertion from both directions. The M_w of the polymers was low and depended on the size of the halo groups.

A new matrix system for phosphorescent OLEDs based on an electron transporting component attached to an inert polymer backbone, an electronically neutral co-host, and a phosphorescent dye that serves as both emitter and hole conductor are presented. The inert co-host is used either as small molecules or covalently connected to the same chain as the electron-transporting host. It is found that to get highest device performance the co-host must present in the matrix in small molecular phase.

The aggregation of a series of linear oligo(ethylene glycol) methacrylate (co)polymers with low molar mass dispersities and well-defined structure was followed in aqueous solutions using light scattering and turbidimetry. The influence of the molar mass, copolymer composition, length of the oligo(ethylene glycol) side chain, concentration of aqueous solution, and heating rate onto the mesoglobule sizes was investigated.

A novel copolymer PCBTBDT with architecture D-A integrated structure is developed. The planar D-A integrated structure favors the strong intermolecular interaction. The typical H-aggregation is beneficial for charge transportation and collection. The copolymer has a low-lying HOMO energy level of −5.41 eV and a broadened absorption. Without any treatment, the PCBTBDT exhibits efficiency of 2% and a relatively high V_oc value of 0.77 V.

An illustration by confocal Raman microscopy of the oxygen-affected layer in a photopolymer cured under air and with visible light is provided. Addition of thiol decreases the OAL and increases the conversion at the surface.

Silicone elastomers are rapidly formed at room temperature using B(C₆F₅)₃ as a catalyst that ligates H-terminated silicone chains with alkoxysilane crosslinkers. The metal free process is extremely rapid: normally the process is slowed down by the addition of small amounts of solvent, which also facilitates the formation of bubble-free transparent elastomers.

The cage/network ratio of PMSQ, having both cage structure and network structure monitored using ²⁹Si NMR and GPC, can be controlled by altering the condensation reaction conditions. Results demonstrate that PMSQ must be designed with a larger cage/network ratio to produce good storage stability and a coating film that has good weather resistance. Additionally, PMSQ must be designed with a smaller cage/network ratio to produce a coating film having high hardness.

The iron (III)-mediated AGET ATRP of MMA using sulfosalicylic acid (SSA) as the ligand was successfully developed. Addition of SSA as the ligand could enhance the polymerization rate and produce PMMA with controllable molecular weights and narrow molecular weight distributions (M_w/M_n = 1.30–1.50). The polymerizations showed characteristics of “living”/controlled free-radical polymerization.

A novel range of ethylene–norbornene copolymers having various composition distributions, including alternating, gradient, block, and block–gradient, have been synthesized by copolymerization with a “living” Pd–diimine catalyst. The tuning of the composition distribution is achieved conveniently by controlling norbornene feed concentration and/or using two- or three-stage polymerization with sequential norbornene feeding.

Traces of ionic liquids (ILs) accelerate the novel imine base/isocyanate (IBI)-mediated radical polymerization of methyl methacrylate (MMA). Both the brutto polymerization rate constant k_Br,0 and the activation temperature of IBI mixtures are influenced. Herein, results are reported on the polymerization kinetics of several IBI combinations in the presence of selected ILs whereas a comparison with non-IL containing initiator mixtures is given. The interaction strength of the IL with each IBI component and MMA was determined by means of ATR FT MIR spectroscopy.

A series of magnesium complexes have been synthesized and their activities toward ROP of lactides were investigated. Kinetic studies and factors affected their activities are also presented.

Dendrimers are a unique class of synthetic macromolecules with highly branched and globular architecture with promising biomedical applications. A highly efficient strategy was developed to make a fifth generation dendrimer within five steps using a combination of aza-Michael addition and Thiol-yne click reactions. All reactions are conducted under benign conditions in the absence of metal catalyst.

The effect of monomer hydrophilicity was investigated in emulsifier-free, organotellurium-mediated living radical polymerization (emulsion TERP) using methyl methacrylate and butyl methacrylate. When hydrophilic monomer was used, MWD control was good only at an efficient and inefficient stirring rates. However, when hydrophobic monomer was used, good MWD control was obtained only at an efficient stirring rate. These results suggest that monomer transportation from droplets to polymerizing particles via aqueous medium is important for good MWD control.

Various elastomeric polypropylenes (PPs) are synthesized with metallocene catalyst (2-PhInd)₂ZrCl₂ in the presence of different cocatalyst mixtures. The catalyst stereoselectivity is sensitive to the nature and amount of included trialkylaluminum. Stereochemical microstructure, molecular weight, melting temperature, glass transition temperature, heat of melt, and elastic damping ability are all polymer properties that can be tuned by controlling the cocatalyst formula. For example, the PP tacticity can be switched from purely atactic to isotactic/atactic stereoblock by the addition of triisobutylaluminum.

In this article, the synthesis and characterization of the first water-soluble and chiral poly(2,4-disubstituted-2-oxazoline)s is described.

Helical folding of poly(naphthalenecarboxamide)s with aliphatic side chains in hydrophobic solvents is investigated. The CD spectra of the polyamide showed a predominant left-handed helical structure in chloroform, THF, and cyclohexane. Furthermore, the sergeants and soldiers experiment in cyclohexane showed a clear chiral amplification. These results indicate that the helical structure was stabilized by an intramolecualr self-association based on the solvophobic effect, and that there is cooperativity between the monomer units constituting the helical structure.