Functional Copolymers Research Articles

Well-Defined Block Copolymers with Triphenylamine and Isocyanate Moieties Synthesized via Living Anionic Polymerization for Polymer-Based Resistive Memory Applications: Effect of Morphological Structures on Nonvolatile Memory Performances

The anionic block copolymerization of 4,4′-vinylphenyl-N,N-bis(4-tert-butylphenyl)benzenamine (A) with n-hexyl isocyanate (B) was performed using potassium naphthalenide (K-Naph) in THF at −78 and −98 °C in the presence of sodium tetraphenylborate (NaBPh4) to afford the well-defined block copolymers for investigating the effect of morphological structures on electrical memory performances. The well-defined functional block copolymers (PBAB) with different block ratios had predictable molecular weights (Mn = 17 700–79 100 g/mol) and narrow molecular weight distributions (Mw/Mn = 1.14–1.19). It was observed from transmission electron microscopy (TEM) that the block copolymers showed different morphological structures depending on block ratios. Although all memory devices fabricated from the resulting block copolymers with different block compositions equally exhibited nonvolatile resistive switching characteristics, which are governed by the trap-controlled space-charge-limited current (SCLC) conduction mec...

Novel functional methacrylate copolymers with side chain tertiary amine and alkynes and their some properties

New methacrylate monomers 2-{[4-(dimethylamino) phenyl] amino}-2-oxoethyl-2-methylacrylate (DMPAMA), and 1-[4-(prop-2-yn-1-yloxy) phenyl] ethanone-O-methacryloyloxime (POEMO) were synthesized first time. The free radical copolymerization of DMPAMA with POEMO has been carried out in 1, 4-dioxane solution at 65 °C ± 1 using 2,2′-azobisisobutyronitrile (AIBN) as an initiator with different monomer-to-monomer ratios in the feed. 1H-NMR was used to determine the molar fractions of DMPAMA and POEMO in the copolymers. The monomer –reactivity ratios were calculated according to the general copolymerization equation using Kelen-Tudos and Finemann-Ross linearization methods. The polydispersity indices of the polymers determined with gel permeation chromatography. The thermal behaviors of copolymers with various compositions were investigated by differential scanning calorimetry and thermogravimetric analysis. The copolymer has been converted into a novel salts by reaction with the iodemethane (CH3I). The electrical conductivity dependence of temperature of the polymers were measured and the polymers exhibit the semiconducting behavior, confirming that the electrical conductivity increases with increasing temperature. All the products showed moderate activity against different strains of bacteria and fungi. In addition, photo-stability tests of the polymers under near-UV irradiation were performed.

Fabrication of Functional Wrinkled Interfaces from Polymer Blends: Role of the Surface Functionality on the Bacterial Adhesion

The generation of nano-microstructured surfaces is a current challenge in polymer science. The fabrication of such surfaces has been accomplished mainly following two different alternatives i.e., by adapting techniques, such as molding (embossing) or nano/microimprinting, or by developing novel techniques including laser ablation, soft lithography or laser scanning. Surface instabilities have been recently highlighted as a promising alternative to induce surface features. In particular, wrinkles have been extensively explored for this purpose. Herein, we describe the preparation of wrinkled interfaces by confining a photosensitive monomeric mixture composed of monofunctional monomer and a crosslinking agent within a substrate and a cover. The wrinkle characteristics can be controlled by the monomer mixture and the experimental conditions employed for the photopolymerization. More interestingly, incorporation within the material of a functional copolymer allowed us to vary the surface chemical composition while maintaining the surface structure. For that purpose we incorporated either a fluorinated copolymer that enhanced the surface hydrophobicity of the wrinkled interface or an acrylic acid containing copolymer that increased the hydrophilicity of the wrinkled surface. Finally, the role of the hydrophobicity on the bacterial surface adhesion will be tested by using Staphylococcus aureus.

Preparation of a new polymer‐dispersed liquid crystal film by using phthalocyanine‐functional photocurable copolymer

ABSTRACTA new, asymmetrical zinc phthalocyanine (aZnPc)‐functional photocurable copolymer was prepared by the combination of atom transfer radical polymerization and copper (I)‐catalyzed azide‐alkyne cyclo‐addition (CuAAC) click reaction and used as polymer matrix of polymer dispersed liquid crystal (PDLC) film. For this purpose, aZnPc was prepared through statistical condensation of 4‐tert‐butylphthalonitrile and 4‐pent‐4‐ynyloxyphthalonitrile. Double CuAAC click reaction between azido‐functional poly(methyl methacrylate‐co‐2‐(2‐bromoisobutyryloxy)‐ethyl methacrylate), terminal alkynyl‐substituted aZnPc, and 4‐ethynyl‐N,N‐dimethyl aniline yielded photocurable aZnPc‐functional copolymer. Thereby, synthesized copolymer was crosslinked in the presence of liquid crystalline mesogen 4′‐(octyloxy)‐4‐biphenylcarbonitrile by ultraviolet irradiation using benzophenone as initiator and ethylene glycol dimethacrylate as difunctional crosslinker. Thermal and optical properties of PDLC film were investigated by using differential scanning calorimetry and polarized optical microscopy. Smectic A liquid crystal mesophases were observed in both PDLC film and its mesogenic component 4′‐(octyloxy)‐4‐biphenylcarbonitrile. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41574.

Toward model‐driven engineering of supramolecular copolymers

ABSTRACTThe coassembly of two oligo‐(p‐phenylene vinylene) (OPV) derivatives with different sizes and opposite chirality is studied. Short R‐chiral ROPV3 molecules experience a high energetic mismatch penalty when incorporated in helices formed by long S‐chiral SOPV4 molecules. In contrast, SOPV4 easily coassembles into helices dominated by ROPV3. As a result, the coassembly behavior (i.e., mixing or phase separation of ROPV3 and SOPV4 within the assemblies) highly depends on the ratio between both molecular building blocks. By a combination of experiments and models, the assembly pathways are analyzed. Furthermore, the model allows identifying key parameters in the coassembly behavior, such as the cooperativity and the mismatch penalties. The model‐driven approach is anticipated to be generally applicable in the engineering of functional supramolecular copolymers. This article is dedicated to the 70th birthday of Jean Fréchet and we thank him for being a continuous source of inspiration for our group. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 385–391

Self-assembly behaviors of thermal- and pH- sensitive magnetic nanocarriers for stimuli-triggered release

In the present work, we prepare thermo- and pH-sensitive polymer-based nanoparticles incorporating with magnetic iron oxide as the remote-controlled, stimuli-response nanocarriers. Well-defined, dual functional tri-block copolymer poly[(acrylic acid)-block-(N-isopropylacrylamide)-block-(acrylic acid)], was synthesized via reversible addition-fragmentation chain-transfer (RAFT) polymerization with S,S′-bis(α,α′-dimethyl-α″-acetic acid)trithiocarbonate (CMP) as a chain transfer agent (CTA). With the aid of using 3-aminopropyltriethoxysilane, the surface-modified iron oxides, Fe3O4-NH2, was then attached on the surface of self-assembled tri-block copolymer micelles via 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride/N-hydroxysuccinamide (EDC/NHS) crosslinking method in order to furnish not only the magnetic resources for remote control but also the structure maintenance for spherical morphology of our nanocarriers. The nanocarrier was characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), and ultraviolet–visible (UV/Vis) spectral analysis. Rhodamine 6G (R6G), as the modeling drugs, was encapsulated into the magnetic nanocarriers by a simple swelling method for fluorescence-labeling and controlled release monitoring. Biocompatibility of the nanocarriers was studied via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, which revealed that neither the pristine nanocarrier nor the R6G-loaded nanocarriers were cytotoxic to the normal fibroblast cells (L-929 cells). The in vitro stimuli-triggered release measurement showed that the intelligent nanocarriers were highly sensitive to the change of pH value and temperature rising by the high-frequency magnetic field (HFMF) treatment, which provided the significant potential to apply this technology to biomedical therapy by stimuli-responsive controlled release.

Functional organo-Mt/copolymer nanoarchitectures. XXII. Interlamellar graft copolymerisation of l-lactic acid onto poly(maleic anhydride-alt-1-octadecene) in the presence of different clays as catalyst-nanofillers

In this work, novel functional copolymer-g-biopolymer layered silicate nanocomposites were prepared by in situ graft copolymerisation of l-lactic acid (LA) onto poly(maleic anhydride-alt-1-octadecene) in the presence of Na+-montmorillonite (Mt), Ag+-Mt and octadecyl amine-Mt (ODA) nanofillers using a specially constructed vacuum micro-reactor with Dean-Stark unit at 80°C. It was observed that inorganic and organic clays executed the dual functions as catalyst of interlamellar graft copolymerisation and nano-filler in formation of clay polymer nanocomposites (CPNs). This new approach allow us to realise the grafting and graft copolymerisation without use of hazardous tin(oct)2 catalyst. The surfactant matrix copolymer provides the first step of grafting via ring opening monoesterification of anhydride units with LA monomer. The catalytic activity of the positively charged clays and their LA preintercalated complexes as a function of phase separation time, strongly depends on the particle parameters (zeta-size and zeta-potential) of the used clay systems and changed in the following range: organoclay<Na+-Mt<Ag+-Mt. The obtained graft copolymer/clay nanohybrids were characterised by FTIR, 1H and 13C NMR, DSC-TGA-DTG, XRD and SEM-TEM analysis methods. These observed that type of the clays significantly influences the chemical and physical structures, thermal properties, surface and internal core–shell morphology of the copolymer-g-PLA layered silicate nanocomposites. Better results were obtained for the copolymer-g-biopolymer/reactive organoclay nanocomposites. It was concluded that this versatile and green synthetic method can utilise for a wide range of anhydride-containing alternating, random, graft and block functional copolymers as matrix polymers and their silicate layered nanocomposites.

Physicochemical characteristics of reduced graphene oxide based Pt-nanoparticles-conducting polymer nanocomposite film for immunosensor applications

BACKGROUNDThis study describes, electrochemically prepared Pt-nanoparticles (PtNP) embedded poly(pyrrole-co-pyrrolepropylic acid) (PPy-PPa) copolymer film over reduced graphene oxide (RGO) sheets deposited on a silane modified indium-tin-oxide coated glass plate. The cardiac myoglobin protein antibody (Ab-Mb) was covalently immobilized on PtNP(PPy-PPa)-RGO nanocomposite through pendant carboxyl groups of the polymer chain using carbodiimide coupling reaction to construct a bioelectrode. The bioelectrode was characterized by high resolution transmission electron microscopy, energy dispersive spectra and electrochemical impedance spectroscopy (EIS). The sensing performance of the bioelectrode was investigated, as an impedimetric immunosensor, for the quantitative detection of the target human cardiac myoglobin antigen (Ag-cMb) in phosphate buffer silane (pH7.4). RESULTSThe EIS studies of the bioelectrode towards Ag-cMb showed a dominant charge transfer resistance (R-et) characteristic in the frequency region 50 to 100Hz. The EIS of the bioelectrode showed an effective immunoreaction with Ag-cMb with a significant increase in both R-et and the constant phase element parameter (n) from 0.61 to 0.85. The bioelectrode exhibited a linear dynamic range of detection from 10ngmL(-1) to 1 mu gmL(-1), sensitivity of 107.08 cm(2) per decade and a lowest detection limit of 4.0ngmL(-1) Ag-cMb. CONCLUSIONThe polymer nanocomposite with uniformly distributed PtNP in conjunction with conducting RGO support has been demonstrated to be a high performance immunosensor. This has been attributed to the synergistic combination of conducting RGO support and electroactive PtNP embedded conducting functional copolymer for efficient covalent biomolecular immobilization, responsible for high protein loading and fast interfacial electron exchange.

Tautomeric acetoacetate monomers as building units of functional copolymers

Although synthetic polymers from tautomeric functional monomers have emerged as a new kind of materials due to potential applications their interest needs still to be revealed. In this work we have synthesized two series of tautomeric acetoacetate copolymers, with different composition, microstructure and properties. We have selected allyl acetoacetate (AAA) and 2-(acetoacetoxy)ethyl methacrylate (AEMA) monomers to copolymerize with styrene (St). The bulk copolymerization initiated with azobisisobutyronitrile was carried out at 60°C for different monomer feed compositions and times. The products were characterized by 1H NMR, HSQC NMR and size exclusion chromatography. The calculated monomer reactivity ratio obtained for poly(St-co-AAA) and for poly(St-co-AEMA), show noteworthy differences in the copolymerization behavior; r1r2 take values near 1 and zero for poly(St-co-AAA) and poly(St-co-AEMA), respectively. The glass transition temperature (Tg) values for copolymers were determined by differential scanning calorimetry. Two Tg temperatures were found for poly(St-co-AAA) which were close to the Tg values of corresponding homopolymers. On the other hand, only one Tg values characterized the St-co-AEMA copolymers system. Thermal stability has been studied by thermo gravimetric analysis (TGA). The copolymers St-co-AAA and St-co-AEMA exhibited higher thermal stability than homopolymer AAA and AEMA, respectively. Due to the functional group present in both monomers, they exhibit tautomeric equilibrium; an interesting NMR study in solution allowed us to demonstrate that the displacement of equilibrium depends on composition, microstructure and solvents. In view of future applications as nanomatrices for tissue engineering, these tautomeric copolymers (St-co-AAA), were nanostructured in AAO nanocavities and its morphological and surface characteristics analyzed by SEM.

Zwitterionic drug nanocarriers: A biomimetic strategy for drug delivery

Nanomaterials self-assembled from amphiphilic functional copolymers have emerged as safe and efficient nanocarriers for delivery of therapeutics. Surface engineering of the nanocarriers is extremely important for the design of drug delivery systems. Bioinspired zwitterions are considered as novel nonfouling materials to construct biocompatible and bioinert nanocarriers. As an alternative to poly(ethylene glycol) (PEG), zwitterions exhibit some unique properties that PEG do not have. In this review, we highlight recent progress of the design of drug nanocarriers using a zwitterionic strategy. The possible mechanism of stealth properties of zwitterions was proposed. The advantages of zwitterionic drug nanocarriers deriving from phosphorylcholine (PC), carboxybetaine (CB), and sulfobetaine (SB) are also discussed.

Europium-complex-grafted polymer dots for amplified quenching and cellular imaging applications.

We report on a europium-complex-grafted polymer for preparing stable nanoparticle probes with high luminescence brightness, narrow emission bandwidth, and long luminescence lifetimes. A Eu complex bearing an amino group was used to react with a functional copolymer poly(styrene-co-maleic anhydride) by the spontaneous amidation reaction, producing the polymer grafted with Eu complexes in the side chains. The Eu-complex-grafted polymer was further used to prepare Eu-complex-grafted polymer dots (Pdots) and Eu-complex-blended poly(9-vinylcarbazole) composite Pdots, which showed improved colloidal stability as compared to those directly doped with Eu-complex molecules. Both types of Pdots can be efficiently quenched by a nile blue dye, exhibiting much lower detection limit and higher quenching sensitivity as compared to free Eu-complex molecules. Steady-state spectroscopy and time-resolved decay dynamics suggest the quenching mechanism is via efficient fluorescence resonance energy transfer from the Eu complex inside a Pdot to surface dye molecules. The amplified quenching in Eu-complex Pdots, together with efficient cell uptake and specific cell surface labeling observed in mammalian cells, suggests their potential applications in time-resolved bioassays and cellular imaging.

Facile anionic synthesis of well-defined block copolymers with pendent triphenylamine and ethynylpyridine for nonvolatile memory device applications with high performances

The sequential block copolymerization of 4,4′-vinylphenyl-N,N-bis(4-tert-butylphenyl)benzenamine (A) with 2-(2-(4-vinylphenyl)ethynyl)pyridine (B) was simply carried out using only potassium naphthalenide (K-Naph) as an initiator without any additives in tetrahydrofuran (THF) at −78 °C. The well-defined functional block copolymers containing A block as an electron donor and B block as a weak electron acceptor had predictable molecular weights (Mn = 8,800–14,500 g/mol) and narrow molecular weight distributions (Mw/Mn = 1.09–1.10). The bicontinuous microphase-separated film morphology of the precisely synthesized poly(B-b-A-b-B) (PBAB) with 0.71 of fpoly(A), formed by thermal annealing at 230 °C for 9 h, was expected to be a potential active layer for nonvolatile memory device applications. Indium tin oxide (ITO)/PBAB/aluminum (Al) memory devices with an 8 × 8 cross-bar array structure exhibited nonvolatile resistive switching characteristics. The memory devices showed reliable memory performance in terms of ON/OFF ratios of ∼104, endurance cycles and retention time, and statistical data with regard to cumulative probability of the switching currents and threshold voltage distribution. Filamentary conduction mechanism was proposed to explain the switching of PBAB-based memory devices. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2625-2632

Development of functional polyplex micelles for systemic gene therapy

Recent advances in chemistry-based engineering have developed smart nanodevices for realizing targeted therapy by rationally integrating versatile molecular technologies to achieve specific structures and functionalities. Gene therapy is one of the most intriguing targets, because nanodevices to deliver fragile DNA into pathological cells and exert effective transgene expression are indispensable for achieving this innovative therapeutic modality. The largest challenge lies in the development of an appropriate systemic delivery system that can withstand the harsh environment of circulating blood and efficiently accumulate in a targeted location for gene expression. This review focuses mainly on our polymer-based DNA delivery systems, which are fabricated from polyion complexation between plasmid DNA and functionalized poly(ethylene glycol)-based block catiomers, and highlights their development to systemic settings for application to cancer treatment. Smart polyplex micelles for systemic gene therapy fabricated by rationally integrating versatile molecular-based technologies. The polyplex micelles, which are formed through an electrostatic interaction-mediated self-assembly process of functional block copolymers and plasmid DNA, assume a task to transport therapeutic gene into nucleus of pathological cells via systemic route for functional protein expression.

Real time optical immunosensing with flow-through porous alumina membranes

Through the presentation of analytical data from bioassay experiments, measured by polarimetry, we demonstrate for the first time a real time immunoassay within a free standing macroporous alumina membrane. The 200nm nominal pore diameter of the membrane enables flow-through, thereby providing an ideal fluidic platform for the targeted delivery of analytes to bioreceptors immobilized on the pore walls, enabling fast sensing response times and the use of small sample volumes (<100μL). For the immunoassay, the pore walls were first coated with the functional copolymer, copoly(DMA-NAS) using a novel coupling process, before immobilization of the allergen protein, β-lactoglobulin, by spotting. The immuno-assay then proceeded with the binding of the primary and secondary antibody cognates, rabbit anti-β-lactoglobulin and anti-rabbit IgG respectively. Through the use of streptavidin coated quantum dots as refractive index signal enhancers, a noise floor for individual measurements of 3.7ng/mL (25pM) was obtained, with an overall statistical, or formal assay LOD of 33.7ng/mL (225pM), for total assay time below 1h.

Synthesis of Thermoresponsive Glycopolymers Combining RAFT Polymerization, Thiol‐Ene Reaction, and Subsequent Immobilization onto Solid Supports

A new monomer, N‐hexenylacrylamide, is copolymerized with N‐isopropylacrylamide by reversible addition‐fragmentation chain transfer (RAFT) polymerization using a carboxylic‐acid‐functionalized RAFT agent. Subsequently, the resulting functional copolymers are reacted with acetylated thiogalactose via a thiol‐ene reaction. After deprotection of the sugar acetyl groups, the glycopolymers show a lower critical solution temperature (LCST) behavior, as confirmed by turbidity measurements. One of these glycopolymers is subsequently immobilized onto solid supports. The obtained products are characterized by attenuated total reflection Fourier transform IR (ATR FTIR) spectroscopy, thermal gravimmetric analysis (TGA), and elemental analysis, confirming the immobilization of the glycopolymer. Additionally, the glycopolymer‐functionalized support shows interaction with the lectin RCA120. image

Three monofunctional copolymers into one multifunctional Micelle: Part 1. Preparation and properties.

In the present work, we propose a new multifunctional micelle, co-self-assembled from different monofunctional copolymers, for tumor targeting and fluorescent and electron spin resonance (ESR) dual detection. Firstly, a poly(D,L-lactic acid)-b-poly(N-isopropyl methacrylamide-co-N-isopropylmaelic acid-co-10-undecenoic acid)-b-poly(N-acryloxysuccinimide) (PLA-PNNUA-PNAS) copolymer, with pH-dependent thermo-responsive properties, was synthesized. The copolymer was synthesized using reversible addition fragmentation chain transfer (RAFT) polymerization method, after which it was further used as a parent copolymer to combine with folic acid (FA), fluorescein isothiocyanate (FITC) and 4-amino-2,2,6,6-tetramethylpiperidin-1-oxyl (4-NH2-TEMPO), respectively, resulting into three new monofunctional copolymers. Finally, the multifunctional copolymer micelle was easily then fabricated, through co-self-assembly, using the monofunctional copolymers. The results from in vitro cell assays indicated that the proposed micelle was able to provide desired multifunctional properties, including tumor specific targeting and fluorescent and ESR dual detection. Additionally, the parent copolymer allowed conjugation with other ligands to prepare them for more functional copolymers attachment for future potential applications. More importantly, the multifunctional properties of the copolymer micelles could be rationally tailored, able for given purposes.

Preparation and biocompatibility of grafted functional β-cyclodextrin copolymers from the surface of PET films

The hydrophobic inert surface of poly(ethylene terephthalate) (PET) film has limited its practical bioapplications, in which case, better biocompatibility should be achieved by surface modification. In this work, the copolymer of functional β-cyclodextrin derivatives and styrene grafted surfaces was prepared via surface-initiated atom transfer radical polymerization (SI-ATRP) on initiator-immobilized PET. The structures, composition, properties, and surface morphology of the modified PET films were characterized by fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), contact angle measurement, and scanning electronic microscopy (SEM). The results show that the surface of PET films was covered by a thick targeted copolymer layer, and the hydrophobic surface of PET was changed into an amphiphilic surface. The copolymer-grafted surfaces were also shown good biocompatibility on which SGC-7901 A549 and A549/DDP cells readily attached and proliferated, demonstrating that the functional copolymer-grafted PET films could be a promising alternative to biomaterials especially for tissue engineering.

Preparation and Characterization of Microgels and Hydrogels Based on Functional Polyphosphoester Diblock Copolymers

Preparation and Characterization of Microgels and Hydrogels Based on Functional Polyphosphoester Diblock Copolymers

ChemInform Abstract: A Guide to the Synthesis of Block Copolymers Using Reversible‐Addition Fragmentation Chain Transfer (RAFT) Polymerization

AbstractReview: 50 refs.

Microencapsulation of liquid and solid substances by reactive polymers

This study is devoted to the development of techniques for the formation of polymeric microcapsules (MC) with either liquid or solid core and with the polymer shell containing diverse functional groups on the basis of new reactive functional copolymers (FC). Two approaches to the formation of MC containing FC shell that included the stages of “oil-in-water” or “water-in-oil” dispersion preparation followed by slow extraction of solvents from dispersed phase by dispersive media were examined. FC with the same structure was successfully applied for both “oil-in-water” and “water-in-oil” systems. Spherical MC with the liquid hydrocarbon core demonstrated essential increase in their volume after heating at the temperature exceeding a boiling point of hydrocarbon encapsulated. Presence of reactive groups in the MC shell opens up new opportunity for further tuning the MC properties via their interaction with proper compounds, particularly via graft-polymerisation of diverse vinyl monomers initiated from the MC surface.