Journal of Polymer Science Part A: Polymer Chemistry

Polyplex nanoparticles for nonviral gene delivery are prepared using plasmid DNA and positively charged poly-D/L aspartate-diethylenetriamine [Poly(D/L Asp-DET)] polymer, as presented by Janni Mirosevich and colleagues on page 836. These polyplexes are capable of transfecting colon and prostate cancer cells in vitro. The confocal fluorescence microscopy image demonstrates in vitro delivery of Cy5-labeled DNA to HCT-116 colon cancer cells using Poly(D/L Asp-DET) Poly(D/L Asp-DET)/Cy5-DNA polyplexes (red), rhodamine phalloidin staining of F-actin (green), and DAPI nuclear stain (blue). In addition, the polyplex nanoparticles could be further modified by covalent attachment of polyethylene glycol (PEG) to produce PEG-polyplexes that are more stable and have more biocompatible characteristics for in vivo delivery applications.

Polymeric films with porous structures and microsphere patterns are prepared by the method of breath figures, mixing poly(methyl methacrylate) (PMMA) and amphiphilic copolymers containing glucose moieties in their structure, glycopolymers, as presented by Juan Rodríguez-Hernández and colleagues on page 851. Depending on experimental conditions (water content, humidity, and type of copolymer), the observed final film morphology changes significantly. Thus, films with honeycomb-patterned structures, spherical particles, or a mixture of both are obtained. In addition, polar glucose moieties are oriented principally either inside of the pores in the case of films and towards the surface in the case of particles. The specific surface bioactivity of these materials is examined using Con A-FITC, where successful binding of Con A is demonstrated by more intense fluorescence at the surface of the pores and of the particles.

Well-defined cyclic poly(acrylic acid) (PAA) has been successfully prepared based on the direct click cyclization. The linear poly(tert-butyl acrylate) (PtBA) with azide and TMS-protected alkyne group forms cyclic chain directly by the copper(I)-catalyzed click cyclization without any deprotection steps. Cyclic PAA is synthesized by the hydrolysis of cyclic PtBA. The present synthetic strategy provides a simple and efficient method to synthesize cyclic polyelectrolyte and can be applied to other polymer systems.

In this work, poly-D/L aspartate-diethylenetriamine [Poly(D/L Asp-DET)] polymers were synthesized and used to complex plasmid DNA to form polyplexes that were capable of transfecting colon and prostate cancer cells in vitro. Subsequently, these polyplexes were further modified by covalent attachment of polyethylene glycol (PEG) to produce PEG-polyplexes that have more biocompatible characteristics for in vivo applications.

Polymeric films with either porous structures or microsphere patterns were prepared by the method of breath figures, mixing high molecular weight PMMA and amphiphilic copolymers containing glucose moieties in their structure, glycopolymers. Films with honeycomb pattern structures, spherical particles, or a mixture of both were obtained by evaporation under controlled ambient conditions. In addition, polar glucose moieties were oriented principally either inside of the pores in the case of films and toward the surface in the case of particles.

The single electron transfer-living radical polymerization of methyl acrylate has been carried out to complete monomer conversion. Using low levels of active Cu(0) wire catalyst and replace 0 to 5% CuBr₂ the reaction reached total conversion with zero termination throughout the polymerization, enabling perfect retention of chain-end functionality.

Siloxane-urethane macromers with carboxylic groups were successfully used to disperse silver nanoparticles (2.5 wt %) prior obtained or one-step in situ generated during UV-light- induced polymerization. Attention is focused on the influence of the monomer structure and composition on the resulting Ag/polymer nanocomposite properties. The formation of hybrid nanocomposites with nanosilver particles (diameter: 2–15 nm) uniformly distributed in the polymer network and stabilized by the acid groups and poly(ethylene oxide) segment from the macrochain was confirmed via UV/vis spectrometry and traditional microscopic techniques such as TEM and ESEM/EDX.

One layer combination of fluorescent polyaniline-sulfonated porphyrin spherical material was successfully prepared by chemical route for the first time. Moreover, this material was synthesized directly from porphyrin using simple and cheaper process and no need of using sulfonated porphyrin, which is a difficult process and also a less available costly material. The electrical and optical properties of this polymer suggest that it may be very useful component in PV/LED devices.

A monomeric hydrophobic fluorophore possessing aggregation-induced emission (AIE) properties was copolymerized with N-(2-hydroxypropyl)methacrylamide to form a series of new copolymers. The copolymers were soluble in water to enable the bioapplications of the hydrophobic AIE fluorophore. The AIE fluorophores aggregated in the cores of micelles formed from the copolymers to show high quantum efficiencies. The polymers were endocytosed by U87MG and CP-A cells.

Easy access to laterally substituted polythiophenes, a class of functional polymers with vast technological potential, is hampered by the difficulty to obtain polymerizable functional monomers in a simple, economically viable, and versatile way. This contribution describes the direct, one-step synthesis of thiophenes bearing dimethylenecraboxylate pendent groups on the 3-position of the heterocycle and the subsequent polymerization of these monomers, using the corresponding ethyl ester monomer as a model.

Uniform polyaniline (PANI) nanospheres have been synthesized in bulk quantities by using cellulose acetate as template in a nonaqueous system for the first time. The diameter of PANI is at the nanoscale, which endows their superior performance as chemical sensors. The PANI nanospheres show super performance in sensitivity, time response, and reversibility to NH₃ even at 1 ppm of NH₃ gas.

A series of new comb polymers containing rod-like side chains, polystyrene-g- poly{2,5-bis[(4-methoxyphenyl)oxycarbonyl]styrene} (PS-g-PMPCS), with different lengths of the backbone and side chains were successfully synthesized by the “grafting onto” method. The PMPCS combs showed different aggregation morphologies when depositing on silicon wafers with/without chemical modification. By using Langmuir-Blodgett technique it was found that the PMPCS comb polymer showed a worm-like chain conformation on polymer-modified silicon wafer.

A hybrid materials with interconnected 3D network of Fe₃O₄-decorated reduced graphene oxide (RGO) and poly(3,4-ethylenedioxythiophene) (PEDOT) was prepared by poly(ionic liquids) (PILs)-mediated hybridization. PILs were found to function as multiple roles for: stabilizing Fe₃O₄-RGO against aggregation, transferring Fe₃O₄-RGO nanomaterials from aqueous into organic phase, and associating Fe₃O₄-RGO nanomaterials with PEDOT. These hybrid materials consisting of graphene, magnetic nanocrystals, and conducting polymers exhibit multifunctional properties such as superparamagnetic behavior, good electrical conductivity, and mechanical properties.

In this work, bimetallic zero-valent metal (Fe(0) and Cu(0)) was used to mediate the SET-LRP of MMA at 25 °C in DMSO. With the increase of the molar ratio of Fe(0) to Cu(0), the polymerization rate was slightly depressed with a prolonged induction period. Interestingly, the control over the molecular weights was improved upon the increase of Fe(0) in a certain range. A best control (initiation efficiency = 91%) was achieved at [Fe(0)]₀/[Cu(0)]₀ = 1/0.5. Explorations of available solvents and ligands confirmed that the Fe(0)/Cu(0)-catalyzed polymerization complied with the SET-LRP mechanism. Fe(0) was suggested to play a dual role in the process: one was the activation agent for Cu(0), which favored a better control over the molecular weights; the other was the alternative catalyst for the activation of R-X or P_n-X to generate radicals, which assured a comparable polymerization rate as that of Cu(0). The Fe(0)/Cu(0) can also be used for the SET-LRP of MA with comparable results of those catalyzed by equivalent Cu(0). This work provided a more economical and environment-friendly catalyst for SET-LRP, and would eventually reinforce the SET-LRP technique.

The Pol/Surf ratio can be significantly increased by increasing the initiator concentration of emulsion polymerization recipes. Particle sizes are comparable to microemulsion latexes, however, less surfactant is required. The reduction in the particle size with higher initiator concentration is attributed to a higher efficiency of particle nucleation and to a higher nucleation rate relative to the rate of monomer transfer. Nanolatexes (particle size < 30 nm) were obtained with 19 wt % soilds content and Pol/Surf of 3.6 in ab initio.

Ring-opening polymerization of D,L-lactide was stereoselectively achieved using newly designed aluminum alkoxide complexes as initiators. These half-SALEN aluminum compounds bearing tridentate nonchiral Schiff-base ligands are racemates, which provide chirality in the aluminum centers, efficiently afforded a stereoblock copolymer of D,L-lactide.

A novel supramolecular cross-linking polymer PBT/F is developed by self-assembly of pendent melamine units in main-chain polymer PBT with uracil motifs in H-bonded cross-linker F. Compared with polymer PBT, a higher power conversion efficiency (PCE) value of 0.86% is obtained in H-bonded cross-linking polymer PBT/F due to its higher crystallinity induced by H-bonded cross-linker F.

Poly(N-isopropylacrylamide) has been a subject of widespread interest for biological applications; however, some applications have been hindered due to the difficulty of maintaining a sharp transition when the polymer is modified for a physiological transition temperature, especially in isotonic solutions. As shown, the combined use of RAFT polymerization, appropriate end groups, molecular weight control, and tacticity control to synthesize well-defined pNIPAAm demonstrate a sharp transition at 37.6 °C under isotonic conditions.

A 5-chloro-3-methoxy salicylaldiminato methylpyridine nickel(II) (left) and its bromo analog were synthesized and applied as single-component catalysts for the polymerization of ethylene in toluene. Catalyst activities were relatively high, and branched polyethylene was obtained as also indicated by the melting points of the polymers (right).

Controlled and very rapid temperature polymerization of tert-butyl acrylate (tBA) was performed using controlled living radical polymerization methods (ATRP and SET-LRP), at ambient temperature. A very active catalyst, secondary initiator and SET-LRP conditions are observed to facilitate very rapid polymerization with good control. SET-LRP enables very fast polymerization with good control even with a primary initiator. Styrene was polymerized from PtBA macroinitiators and vice versa to obtain block copolymers. The amphiphilic block copolymers obtained by the hydrolysis of the tBA block enable the formation of stable dispersion of CdS nanoparticles.

Generally, protection and deprotection procedures of amino groups are required in preparing propargyl ether-containing benzoxazine. In this study, a deprotection-free preparation of a propargyl ether-containing phosphinated benzoxazine is reported.

Liquid polybutadiene rubber (LBR) is regarded as an internal olefinic multivinyl crosslinker. First, gelation in the polymerization of LBR was explored, especially at elevated temperatures. The occurrence of intermolecular crosslinking was easier in the order (A) LBR > (B) LBR containing 20 mol % of 1,2-structural units > (C) liquid polyisoprene rubber. Then, the dicumyl peroxide-initiated LBR polymerization was pursued: the ratio of allylic hydrogen abstraction to β-scission reaction of cumyloxy radical was estimated; thus, only 39% of cumyloxy radical was used for the allylic hydrogen abstraction reaction. Finally, the intermolecular and intramolecular skewered reactions were pursued in crosslinking LBR/vinyl pivalate copolymerizations.

A series of furan-aromatic polyesters are readily prepared via direct esterification method starting from 2,5-furandicarboxylic acid, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, and 1,8-octanediol. The preliminary evidence shows that direct esterification method is rewarding and worthy to prepare furan-aromatic polyesters. The research results shows that furan-aromatic polyesters (ρ = 1.19–1.38 kg/m³) are crystalline and hydrophilic, they have satisfactory thermal and mechanical properties, and their thermal stabilities are quite similar to that of corresponding benzene-aromatic polyesters, which would endow them to be a viable alternative to their successful petrochemical benzene-aromatic counterpart and to be used as biopolymer materials in the future.

The casting of bulk-hetero junction P3HT/PC60BM 1/1 active layers by doctor blading from solutions in toluene leads to an improved nanocrystallinity when compared with their unannealed, chlorobenzene-casted counterparts. Despite that this is not noticed in the TEM images, solid-state NMR and rapid heating cooling calorimetry experiments, on the other hand, reveal these subtle differences, making them powerful and complementary techniques to investigate the active layer morphology of plastic solar cells.