Journal of Polymer Science Part A: Polymer Chemistry

A robust sequential interpenetrating network (SeqIPN) methodology is proposed on page 363 by Ting Yang, Michael Malkoch, and Anders Hult for the fabrication of polyethylene glycol (PEG) based IPN hydrogels. By employing the highly efficient and UV initiated thiol-ene coupling chemistry, a comprehensive library of hydrogels is produced covering a broad window of swelling and mechanical properties. As a result, PEG hydrogels can accurately be fine-tuned beyond the limited boundaries of traditional single network hydrogels.

The thermal, optical, electrochemical, and electronic properties of the copolymers P(T-Qx), P(BDT-Qx), and P(BDT-DTQx), based on the electron-deficient Qx unit, are fully characterized as presented by Yuanhe Fu, Hyojung Cha, Seulki Song, Gang-Young Lee, Chan Eon Park, and Taiho Park on page 372. P(T-Qx) exhibits the most rigid planar structure of the three copolymers. The lower hole mobility of P(BDT-DTQx) than that of P(T-Qx) indicates that the incorporation of a BDT unit does not improve the photoactive materials of Qx-based copolymers. This systematic study deepens the understanding of the role of BDT in Qx-based copolymer systems. The principles described here may be extended to other types of donor and acceptor units toward the design of a novel class of photoactive materials.

A series of novel conjugated polymers PTPE_xF_y have been synthesized, which have aggregation-induced emission enhancement (AIEE) and dual-channel fluorescence response (DCFR) when they are aggregated in solution. The AIEE and DCFR properties are related to the tetraphenylethylene (TPE)-to-fluorene ratio in the polymer backbone and can be attributed to the different responses of the fluorene segments and the TPE segments to aggregation. The fluorene segments have an aggregation-caused quenching characteristic, whereas the TPE segments have an aggregation-induced emission characteristic.

Dihydroindeno[2,1-a]indene, MBI and thiophene (or bithiophene) units were incorporated using Stille and Suzuki polymerization to generate PININEDTMBIs (or PININEBBTMBIs). In case of the most efficient polymer, PININEBBTMBI, the device with the configuration of ITO/PEDOT:PSS/polymer:PC₇₁BM(1:4w/w)/Al, annealed at 100 °C for 10min demonstrated a V_OC of 0.78 V, a J_SC of 6.66 mA/cm², and a FF of 0.41, leading tothe power conversion efficiency of 2.11%, under white light illumination (AM 1.5 G, 100 mW/cm²).

Amphiphilic macro-reversible addition fragmentation chain transfer copolymers were used as both stabilizers and chain transfer agents in the preparation of polymer-coated COOH-functionalized multiwalled carbon nanotubes via disperse phase polymerization.

Two conjugated PBDTDPPcbp and PCBTDPPcbp bearing liquid-crystalline pendants are synthesized. The polymer with benzodithiophene possesses a low-lying HOMO level to provide a higher open-circuit voltage. The orientation of mesogenic pendants induced the polymer:PCBM blends to form well-connected nanoscale phase separation. The alternative polymers with benzodithiophene and carbazole lead to PCE of 1.3% and 1.2% after annealing, respectively.

Crosslinked polymer nanospheres prepared by nonaqueous (mini)emulsion polymerization and imprinted with the drug propranolol exhibit enhanced rebinding of the propranolol template molecule compared to nonimprinted samples as well as enantioselectivity in the rebinding process.

New Y-type polyurethane 5 containing 4-(2′,2′-dicyanovinyl)-6-nitroresorcinoxy groups as nonlinear optical (NLO) chromophores was prepared. The resulting polyurethane 5has a thermal stability up to 280 °C with T_g value around 120 °C. The second harmonic generation (SHG) coefficient (d₃₃) of poled polymer film at 1064 nm fundamental wavelength is around 6.12 × 10⁻⁹ esu. The polymer exhibits a SHG thermal stability even at 5 °C higher than T_g, and there is no SHG decay below 125 °C. This enhanced thermal stability of optical nonlinearity stems from the stabilization of dipole alignment of the NLO chromophores, which are part of the polymer main chain.

Biodegradable and thermoresponsive poly(carbonate-ether)s (PCEs) with carbonate unit (CU) content of 1.0–42.4 mol % and molecular weight of 2.7–247 kg/mol were synthesized in high yield by copolymerization of CO₂ and ethylene oxide under double metal cyanide catalyst. The lower critical solution temperature (LCST) window of PCE can be tunable in a range of 21.5–84.1 °C by controlling the CU content and the molecular weight via the adjustment of polymerization conditions. In particular, aqueous solution of PCE with 26.0 mol % of CU exhibited an LCST around 36.1 °C, very close to body temperature.

The synthesis of a diblock copolymer is described, which undergoes spontaneous assembly into cylindrical patterns. The matrix surrounding the cylinders can be selectively etched away to leave structures with dimensions on the nanoscale. The orientation and ordering of these structures is demonstrated. Structures of this sort are valuable for use in nano-manufacturing of devices such as microelectronics and hard disk drives.

A bifunctional N-glycoside was prepared by N-glycosylation of 1,6-hexamethylenediamine with D-glucose and used as a monomer for synthesizing polyureas with glucose-derived pendants without protecting their hydroxyl groups.

Photopolymerization of well-defined polyisobutylene-based macromonomers with acrylate, methacrylate, or vinyl ether end groups generates useful polymeric networks. The kinetics of photocrosslinking were measured using an optical pyrometer apparatus. The rates of photopolymerization were manipulated and optimized with respect to different experimental parameters. Analysis of photopolymerized networks by attenuated total reflectance-Fourier transform infrared spectroscopy indicated nearly complete end group double bond conversion. A similar conclusion was reached from solvent extraction studies.

Telechelic polymers with hydroxyl groups at both the chain ends were precisely synthesized byRAFT polymerization of vinyl monomers using a new trithiocarbonate 1.

Titanium complexes with various iminophenolate ligands were synthesized and their suitability as catalysts for the ring-opening polymerization of L-lactide and ε-caprolactone were investigated. Complexes with bidentate ligands demonstrate higher catalytic activity than their tridentate counterparts and the differences in the geometric framework of bidentate ligands also influence the catalytic activity. Type II ligands formblocks in more positions which increases their effectiveness in preventing the coordination of monomers to Ti thereby decreasing the initiation rate.

[2.2]Paracyclophane-based through-space conjugated polymers were prepared, in which π-electron systems, i.e., poly(p-arylene-ethynylene) units, are partially π-stacked and layered one-dimensionally. In the polymers, fluorescence quenchers, such as anthraquinone and ferrocene, exist at the polymer termini. Fluorescence emission from the stacked π-electron systems is effectively quenched by the terminal π-electron systems through the polymer chain.

The synthesis of PAN via living radical polymerization in DMF using CCl₄ as initiator, CuCl₂/HMTA as catalyst system, and AIBN as a radical initiator, is reported. The polymerization proceeds in controlled/living manner as indicated by first-order kinetics of the polymerization rate with respect to the monomer concentration, linear increase of the molecular weight with monomer conversion, and narrow polydispersity. The modified PAN containing amidoxime group was used for extraction of Ag(I) ions from aqueous solutions.

mPEG-b-P(CB-co-LA-co-MAC) and mPEG-b-PMAC-b-P(CB-co-LA) were synthesized preparing micelles, which were stabilized by crosslinking via radical polymerization of double bonds in the core and interface. These crosslinked micelles demonstrated enhanced stability against extensive dilution with aqueous solvents and in the presence of serum. Bicalutamide-loaded crosslinked micelles were more potent compared to noncrosslinked micelles in inhibiting LNCaP cell proliferation. These results suggest crosslinked micelles to be promising drug delivery vehicles for chemotherapy.

This article describes the exploitation of the UV-initiated thiol-ene coupling chemistry for the preparation of interpenetrating network (IPN) hydrogels based on polyethylene glycol of 2–8 kDa. The facile methodology resulted in the assembly of a comprehensive library of sequential IPNs with gel fractions above 85%. As a result, parameters such as the swelling degree and the tensile modulus were effectively controlled to cover a wider range that goes beyond simple primary networks.

A series of low-bandgap polymers, P(T-Qx), P(BDT-Qx), and P(BDT-DTQx), based on electron-deficient Qx unit has been synthesized. Among them, P(T-Qx) having a stronger electron donor showed the most rigid planar structure, providing a high hole mobility and high performance in the solar cell. On the contrary, the P(BDT-Qx)-based solar cell had lower power conversion efficiency with the largest torsional angle between BDT and Qx units. The BDT unit in the P(BDT-DTQx) backbone acted as a linker, which interfered in the formation of the charge complexation and the quinoidal electronic conformation in one polymer chain.

Ethynylene-containing donor-acceptor alternating conjugated polymers with 2,5-bis(dodecyloxy) substituted phenylene or carbazole as the donor unit and benzothiadiazole (BTZ) as the acceptor unit have been synthesized and used as donor polymers in bulk heterojunction polymer solar cells. Absorption spectra and the HOMO and LUMO energy levels of polymers could be tuned by varying the position of the ethynylene unit in the polymer chains. These ethynylene containing conjugated polymers show higher open circuit voltages.

Gas responsive homo- and AB diblock copolymers based on histamine and arginine have been prepared via RAFT polymerization employing activated ester chemistry. Quantitative formation of histamine and arginine (co)polymers was verified by ¹H NMR spectroscopy giving stimulus responsive materials capable of undergoing reversible self-assembly employing CO₂/H₂O and N₂ as triggers.

The living copolymerization kinetics of ethylene with 1-octene was studied with the fluorinated FI-Ti catalyst system. The livingness behavior was retained at an extremely high comonomer feeding ratio of 0.953. The comonomer incorporation reached up to 32.7 mol %. The copolymer composition drifting was minor. The reactivity ratios were determined and it was found that heterogeneity had a significant effect on the copolymerization kinetics. The reactivity ratios were independent of temperature in the range of 0–35°C.

Two strategies for the synthesis of phosphonic acid-terminated poly(ethylene oxide) are compared, which used a combination of “click” chemistry and Kabachnik–Fields or Atherton-Todd reaction. The best flexible method uses in a first step the Kabachnik–Fields reaction of dimethyl phosphonate and propargylbenzylimine to yield the corresponding propargyl aminophosphonate. In a second step, “click” reaction with azido-terminated PEO followed by acidic hydrolysis leads to phosphonic acid-terminated poly(ethylene oxide).

A series of thieno[3,2-b]thiophene and isoindigo-based polymers with D–π–A backbones have been synthesized. Their optoelectronic properties were tuned and optimized by using D−π−A conjugated main chains. Efficient bulk-heterojunction polymer solar cells were fabricated using these electron donor and hole transport materials.

N-vinyl formamide (NVF) is an isomer of acrylamide (AAm), yet PNVF gels have not been synthesized and characterized, unlike widely used PAAm gels. Because NVF is liquid, less toxic than AAm, and because PNVF gels can be efficiently hydrolyzed to polyvinylamine, PNVF gels could also have significant technological utility. Thus solution-cast, molded poly(N-vinyl formamide) hydrogels were created by copolymerization/crosslinking of aqueous NVF with a novel cross-linker, 2-(N-vinylformamido) ethylether (NVEE). PNVF gels are slightly more hydrophilic than PAAm gels in terms of the χ parameter, but gels of the same polymer volume fraction have the same moduli and fracture properties.

A (PEO-PS)₂-PLA terpolymer self-assembles into a two-phase columnar structure consisting of poly(ethylene oxide) (PEO)/polylactide (PLA) cylindrical domains in a rigid polystyrene (PS) matrix. In contrast, the ion doping of the PEO block induces a three-phase lamellar morphology. Meanwhile, by eliminating the confined PLA block in the columnar morphology, a nanoporous material with hydrophilic PEO walls can be produced.

Cellulose produced from cotton fibers was used as substrate for synthesis of oil-absorbing materials by SET-LRP. The cellulose macroinitiator was prepared by esterification of hydroxyl group with BiBB, followed by grafting with BMA and PETA to render a three-dimensional architecture. The polymerization was catalyzed by Cu(0)/HMTA. The maximum oil absorption to chloroform and toluene could reach 29.0 and 15.4 g·g⁻¹, respectively.

Novel stereoregular carbohydrate-derived [m,n]-polyurethanes have been prepared using D-mannitol (1) as renewable and low cost starting material. The key comonomer, 1,6-di-O-phenylcarbonyl-2,3,4,5-tetra-O-methyl-D-mannitol, was polymerized with a diamine synthesized from 1 or with alkylenediamines. These polymerizations led, respectively, to a [6,6]-polyurethane entirely based on a carbohydrate or to [m,n]-polyurethanes constituted by a poly-O-methyl substituted unit alternating with a polymethylene chain. Thermal studies (DSC) indicated that polymers are amorphous materials with T_g values dependent on the structure and chain length of the diamine constituent.