A combining signal amplification of atom transfer radical polymerization and redox polymerization for visual biomolecules detection

A novel combination of atom transfer radical polymerization (ATRP) and redox polymerization is here used to allow instrument‐free visualization of special biomolecules for which dynamic polymer growth is used in signal amplification. In this method, the convenient and mild redox polymerization‐assisted amplification with cerium ammonium (IV) nitrate as oxidant at the second stage was achieved by directly using the hydroxyl groups from poly(hydroxyethyl methacrylate) (PHEMA) synthesized via ATRP at the first stage. The brushed polymers poly(hydroxylethyl methacrylate)‐branched‐poly (acrylamide) (PHEMA‐branched‐PAM) prepared by successive ATRP and redox polymerization in situ drastically grew up at the detected biomolecules spot to improve the visibility of biomolecule and simplify the detection procedure. With the proposed strategy, the signal amplification of streptavidin (SA) as model detected biomolecule was investigated on two different substrates such as silicon wafer and gold, respectively. As a result, detection limit of SA was demonstrated on the gold substrates where binding of 1.0 ng/mL SA was differentiable from the background using ellipsometry. Moreover, binding of 0.5 nmol/L DNA led to visually distinguishable spots on the gold surface under mild condition. The proposed method exhibited an efficient amplification performance for molecules detection, and paved a new way for visual diagnosis of biomolecules. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2791–2799     

Biotin functionalized poly(sulfonic acid)s for bioconjugation: In situ binding monitoring by QCM‐D

We describe the synthesis of biotin end functionalized poly(sulfonic acid)s via living radical polymerization (LRP) for conjugation to Avidin. Quartz crystal microbalance (QCM‐D) and competitive binding studies were used to confirm this conjugation. A biotin initiator for copper‐mediated LRP was used to provide acrylamide and methacrylate based polymers with the functional end group. This investigation revealed that 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid was not a suitable monomer in its acid form but was successfully used in its sodium salt form. A second monomer, 3‐sulfopropylmethacrylate as the potassium salt was also studied and both monomers produced polymers with polydispersities <1.3 and 1.4, respectively. Evolution of molecular weight with respect to time indicated that the polymerization of the acrylamide polymer is controlled. Quartz crystal microbalance with dissipation monitoring was used to confirm that the biotinylated polymers were able to bind to Avidin in situ. The gold surface of a quartz crystal was chemically modified resulting in a stable monolayer of Avidin; the biotinylated polymers were passed over the functionalized surface and their grafting ability was examined. A competitive binding evaluation was undertaken with 2‐(4‐hydroxyphenylazo)benzoic acid (HABA) dye to provide visual verification of conjugation. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Molecularly imprinted polymers bearing spiropyran‐based photoresponsive binding sites capable of photo‐triggered switching for molecular recognition activity

Photoresponsive molecularly imprinted nanocavities were prepared using a newly designed functional monomer bearing a photoresponsive spiropyran moiety with a carboxy group that can interact with atrazine (the template molecule), in which the spiropyran moiety was incorporated into the binding cavities. Spectrophotometric analysis confirmed that the spiropyran moiety was photoresponsive even after polymerization. The selectivity of the EDMA‐based molecularly imprinted polymer (MIP_EDMA) was tested to examine the binding behavior of atrazine and other agrochemicals, revealing that the atrazine‐imprinted polymer can bind selectively to triazine herbicides. Photo‐triggered switching of the binding activity in MIP_EDMA was investigated, and the binding activity was found to decrease dramatically after UV light irradiation, suggesting that the spiropyran moiety in the binding cavities was transformed to the merocyanine form, resulting in unfavorable translocation of the carboxy group for atrazine binding. Consequently, the spiropyran‐based MIP_EDMA demonstrated in this study could open a way to realizing reliable photoresponsive smart materials. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1637–1644     

Patterned immobilization of biomolecules by using ion irradiation‐induced graft polymerization

A new method for biomolecular patterning based on ion irradiation‐induced graft polymerization was demonstrated in this study. Ion irradiation on a polymer surface resulted in the formation of active species, which was further used for surface‐initiated graft polymerization of acrylic acid. The results of the grafting study revealed that the surface graft polymerization using 20 vol % of acrylic acid on the poly(tetrafluoroethylene) (PTFE) film irradiated at the fluence of 1 × 10¹⁵ ions/cm² for 12 h was the optimum graft polymerization condition to achieve the maximum grafting degree. The results of the fluorescence microscopy also revealed that the optimum fluence to achieve the maximum fluorescence intensity was 1 × 10¹⁵ ions/cm². The grafting of acrylic acid on the PTFE surfaces was confirmed by a fluorescence labeling method. The grafted PTFE films were used for the immobilization of amine‐functionalized p‐DNA, followed by hybridization with fluorescently tagged c‐DNA. Biotin‐amine was also immobilized on the acrylic acid grafted PTFE surfaces. Successful biotin‐specific binding of streptavidin further confirmed the potential of this strategy for patterning of various biomolecules. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6124–6134, 2009     

Solution polymerization of polybenzimidazole

Polybenzimidazoles (PBI) are an important class of heterocyclic polymers that exhibit high thermal and oxidative stabilities. The two dominant polymerization methods used for the synthesis of PBI are the melt/solid polymerization route and solution polymerization using polyphosphoric acid as the solvent. Both methods have been widely used to produce high‐molecular weight PBI, but also highlight the obvious absence of a practical organic solution‐based method of polymerization. This current work explores the synthesis of high‐molecular weight meta‐PBI in N,N‐dimethyl acetamide (DMAc). Initially, model compound studies examined the reactivity of small molecules with various chemical functionalities that could be used to produce 2‐phenyl‐benzimidazole in high yield with minimal side reactions. ¹H NMR and FTIR studies indicated that benzimidazoles could be efficiently synthesized in DMAc by reaction of an o‐diamine and the bisulfite adduct of an aromatic aldehyde. Polymerizations were conducted at various polymer concentrations (2‐26 wt % polymer) using difunctional monomers to optimize reaction conditions in DMAc which resulted in the preparation of high‐molecular weight m‐PBI (inherent viscosities up to 1.3 dL g^?1). TGA and DSC confirmed that m‐PBI produced via this route has comparable properties to that of commercial m‐PBI. This method is advantageous in that it not only allows for high‐polymer concentrations of m‐PBI to be synthesized directly and efficiently, but can be applied to the synthesis of many PBI derivatives. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1795–1802     

Study of the composition and morphology of new modifications of titanium‐magnesium catalysts with improved properties in ethylene polymerization

Data on new modifications of supported titanium‐magnesium catalysts (TMCs) with improved performance in ethylene polymerization are reported. These catalysts possess a high and stable activity, an enhanced ability to regulate molecular weight of the polymer by hydrogen, a controllable particle size at a narrow particle size distribution, and the ability to produce the polymer with an increased bulk density. Various physicochemical methods were used to obtain data on the chemical composition of novel supports and catalysts, their phase composition and crystal structure as well as the pore structure. The results obtained were used to discuss possible correlations between composition and structure of TMCs and their catalytic properties. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2545–2558     

α‐exomethylene lactone possessing acetal–ester linkage: Polymerization and postpolymerization modification for water‐soluble polymer

2,6‐Dimethyl‐5‐methylene‐1,3‐dioxa‐4‐one (DMDO), a cyclic acrylate possessing acetal–ester linkage, was obtained as a mixture of cis‐ and trans‐isomers (95:5) from Baylis–Hillman reaction of an aryl acrylate. The radical and anionic polymerizations of DMDO yielded the corresponding vinyl polymers without any side reactions such as cleavage of the acetal–ester linkage. The polymerization behaviors were significantly different from that of the acyclic acrylate, α‐(hydroxymethyl)acrylic acid, which was expected inactive against polymerization due to the steric hindrance around the vinylidene group by the α‐substituent. The acetal–ester linkage of the obtained polymer ( P1 ) was completely cleaved via acid hydrolysis to afford a water soluble polymer, P2 . © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 955–961     

Synthesis of pH‐ and thermoresponsive poly(2‐n‐propyl‐2‐oxazoline) based copolymers

Polymers that possess lower critical solution temperature behavior such as poly(2‐alkyl‐2‐oxazoline)s (PAOx) are interesting for their application as stimulus‐responsive materials, for example in the biomedical field. In this work, we discuss the scalable and controlled synthesis of a library of pH‐ and temperature‐sensitive 2‐n‐propyl‐2‐oxazoline P(nPropOx) based copolymers containing amine and carboxylic acid functionalized side chains by cationic ring opening polymerization and postpolymerization functionalization strategies. Using turbidimetry, we found that the cloud point temperature (CP) is strongly dependent on both the polymer concentration and the polymer charge (as a function of pH). Furthermore, we observed that the CP decreased with increasing salt concentration, whereas the CP increased linearly with increasing amount of carboxylic acid groups. Finally, turbidimetry studies in PBS‐buffer indicate that CPs of these polymers are close to body temperature at biologically relevant polymer concentrations, which demonstrates the potential of P(nPropOx) as stimulus‐responsive polymeric systems in, for example, drug delivery applications. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1573–1582     

Stable,High‐Molecular‐Weight Poly(phthalaldehyde)

Low ceiling temperature, thermodynamically unstable polymers have been troublesome to synthesize and keep stable during storage. In this study, stable poly(phthalaldehyde) has been synthesized with BF₃‐OEt₂ catalyst. The role of BF₃ in the polymerization is described. The interaction of BF₃ with the monomer is described and used to maximize the yield and molecular weight of poly(phthalaldehyde). Various Lewis acids were used to investigate the effect of catalyst acidity on poly(phthalaldehyde) chain growth. In situ nuclear magnetic resonance was used to identify possible interactions formed between BF₃ and phthalaldehyde monomer and polymer. The molecular weight of the polymer tracks with polymerization yield. The ambient temperature stability of poly(phthalaldehyde) was investigated and the storage life of the polymer has been improved. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 55, 1166–1172     

Efficient fabrication of polymer nanoparticles via sonogashira cross‐linking of linear polymers in dilute solution

The synthesis of single‐chain nanoparticles by palladium‐catalyzed Sonogashira coupling between a terminal alkyne and a di‐halo aryl cross‐linker is reported. Statistical copolymers with trimethylsilyl protected alkyne groups pendent to the linear methacrylate back bones were synthesized using reversible addition‐fragmentation chain transfer polymerization post polymerization de‐protection providing terminal alkyne functionalized linear polymer chains. These linear polymer chains were intramolecularly cross‐linked via bifunctional cross‐linkers. The resulting well‐defined covalently bonded nanoparticles were characterized via triple‐detection size exclusion chromatography where MALS detector provided molecular weight information and viscometric detection characterizes particle size and conformations. The particle size could be readily tuned through polymer molecular weight and by degree of cross‐linking. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 209–217     

Recent progress on cyclic polymers: Synthesis,bioproperties, and biomedical applications

Polymer topologies exert a significant effect on its properties, and polymer nanostructures with advanced architectures, such as cyclic polymers, star‐shaped polymers, and hyperbranched polymers, are a promising class of materials with advantages over conventional linear counterparts. Cyclic polymers, due to the lack of polymer chain ends, have displayed intriguing physical and chemical properties. Such uniqueness has drawn considerable attention over the past decade. The current review focuses on the recent progress in the design and development of cyclic polymer with an emphasis on its synthesis and bio‐related properties and applications. Two primary synthetic strategies towards cyclic polymers, that is, ring‐expansion polymerization and ring‐closure reaction are summarized. The bioproperties and biomedical applications of cyclic polymers are then highlighted. In the end, the future directions of this rapidly developing research field are discussed. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1447–1458     

Thermoresponsive poly(ionic liquid): Controllable RAFT synthesis,thermoresponse, and application in dispersion RAFT polymerization

The thermoresponsive poly(ionic liquid) of poly[1‐(4‐vinylbenzyl)‐3‐methylimidozolium tetrafluoroborate] trithiocarbonate (P[VBMI][BF₄]‐TTC) showing the soluble‐to‐insoluble phase transition in the methanol/water mixture at the upper critical solution temperature (UCST) was synthesized by solution RAFT polymerization and the synthesized P[VBMI][BF₄]‐TTC was employed as macro‐RAFT agent to mediate the RAFT polymerization under dispersion condition to afford the thermoresponsive diblock copolymer nanoparticles of poly[1‐(4‐vinylbenzyl)‐3‐methylimidozolium tetrafluoroborate]‐b‐polystyrene (P[VBMI][BF₄]‐b‐PS). The controllable solution RAFT polymerization was achieved as indicated by the linearly increasing polymer molecular weight with the monomer conversion and the narrow molecular weight distribution. The P[VBMI][BF₄]‐TTC macro‐RAFT agent mediated dispersion polymerization afforded the P[VBMI][BF₄]‐b‐PS nanoparticles, the size of which was uncorrelated with the polymerization degree of the P[VBMI][BF₄] block. Several parameters including the polymerization degree, the polymer concentration and the water content in the solvent of the methanol/water mixture were found to be correlated with the UCST of the poly(ionic liquid). The synthesized poly(ionic liquid) is believed to be a new thermos‐responsive polymer and will be useful in material science. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 945–954     

Synthesis of chitosan‐based thermo‐ and pH‐responsive porous nanoparticles by temperature‐dependent self‐assembly method and their application in drug release

In this research, thermo‐ and pH‐responsive chitosan‐based porous nanoparticles were prepared by the temperature‐dependent self assembly method. The chitosan‐graft‐poly(N‐isopropylacrylamide) (CS‐g‐PNIPAAm) copolymer solution was prepared through polymerization of N‐isopropylacrylamide (NIPAAm) monomer in the presence of chitosan (CS) solution using cerium ammounium nitrate as the initiator. Then, CS‐g‐PNIPAAm solution was diluted by deionized water and heated to 40 °C for CS‐g‐PNIPAAm self‐assembly. After that, CS‐g‐PNIPAAm assembled to form micelles in which shell layer was CS. Crosslinking agent was used to reinforce the micelle structure to form nanoparticle. The molar ratio of CS/NIPAAm in the feed mixture was changed to investigate its effect on structure, morphology, thermal‐ and pH‐responsive properties of the nanoparticles. TEM images showed that a porous structure of nanoparticles was developed. The synthesized nanoparticles carried positive charges on the surface and exhibited stimuli‐responsive properties, and their mean diameter thus could be manipulated by changing pH value and temperature of the environment. The nanoparticles showed a continuous release of the encapsulated doxycycline hyclate up to 10 days during an in‐vitro release experiment. These porous particles with environmentally sensitive properties are expected to be utilized in hydrophilic drug delivery system. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5126–5136, 2009     

Synthesis of poly(ω‐pentadecalactone)‐b‐poly(acrylate) diblock copolymers via a combination of enzymatic ring‐opening and RAFT polymerization techniques

Herein the first reported preparation of diblock copolymers of the polyethylene‐like polyester poly(ω‐pentadecalactone) (PPDL) via a combination of enzymatic ring‐opening polymerization (eROP) and reversible addition‐fragmentation chain‐transfer (RAFT) polymerization techniques is described. PPDL was synthesized via eROP using Novozyme 435 as a catalyst and a bifunctional initiator/chain transfer agent (CTA) appropriate for the eROP of ω‐pentadecalactone (PDL) and RAFT polymerization of acrylic and styrenic monomers. Chain growth of the PPDL macro‐CTA was performed to prepare acrylic and styrenic diblock copolymers of PPDL, and demonstrates a facile, metal‐free, and “greener” alternative to preparing acrylic diblock copolymers of polyethylene (PE). Diblock copolymer architecture was substantiated via analysis of ¹H NMR spectroscopic, UV‐GPC chromatographic, DSC onset crystallization (T_c), and MALDI‐ToF mass spectrometric data. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3326–3335     

Cyclic peptide–polymer conjugates: Grafting‐to vs grafting‐from

A systematic comparison between the grafting‐to (convergent) and grafting‐from (divergent) synthetic routes leading to cyclic peptide–polymer conjugates is described. The reversible addition–fragmentation chain transfer (RAFT) process was used to control the polymerizations and the couplings between cyclic peptide and polymer or RAFT agent were performed using N‐hydroxysuccinimide (NHS) active ester ligation. The kinetics of polymerization and polymer conjugation to cyclic peptides were studied for both grafting‐to and grafting‐from synthetic routes, using N‐acryloyl morpholine as a model monomer. The cyclic peptide chain transfer agent was able to mediate polymerization as efficiently as a traditional RAFT agent, reaching high conversion in the same time scale while maintaining excellent control over the molecular weight distribution. The conjugation of polymers to cyclic peptides proceeded to high conversion, and the nature of the carbon at the α‐position to the NHS group was found to play a crucial role in the reaction kinetics. The study was extended to a wider range of monomers, including hydrophilic and temperature responsive acrylamides, hydrophilic and hydrophobic acrylates, and hydrophobic and pH responsive methacrylates. Both approaches lead to similar peptide–polymer conjugates in most cases, while some exceptions highlight the advantages of one or the other method, thereby demonstrating their complementarity. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1003–1011     

Monodisperse superparamagnetic pH‐sensitive single‐layer chitosan hollow microspheres with controllable structure

Facile strategy was developed for the fabrication of the monodisperse superparamagnetic pH‐sensitive single‐layer chitosan (CS) hollow microspheres with controllable structure. The carboxyl group‐functionalized polystyrene microspheres prepared by soap‐free emulsion polymerization were used as the templates. After the Fe₃O₄ nanoparticles were in situ formed onto the surface of the templates, the single‐layer CS was self‐assembled and cross‐linked with glutaraldehyde subsequently. Then, the magnetic single‐layer CS hollow microspheres were obtained after the templates were removed. It was found that the feeding ratio of the monomer acrylic acid in the soap‐free emulsion polymerization had played an important role on the particle size and surface carboxyl group content of the templates, which determined the particle size and shell thickness of the magnetic single‐layer CS hollow microspheres in the proposed strategy. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Revised insights into templating radical polymerization within nanoreactors

The field of polymer chemistry is currently experiencing major research efforts into development of novel techniques for synthesis of polymers with well‐controlled microstructure. Recently, a new method has been reported [McHale et al., Nat. Chem. 2012, 4, 491–497] whereby high molecular weight and low dispersity polymer can be obtained by a radical polymerization process via the use of solely physico‐chemical interactions. This work was based on the combination of H‐bonding templated polymerization confined within nanoreactors of self‐assembled block copolymers. Herein, this system is thoroughly investigated to fully elucidate the underlying mechanism. Modification of physico‐chemical parameters, kinetic parameters as well as observations of size exclusion chromatography (SEC) results and colloidal behavior in various solvents provide revised insights into the mechanism. Through detailed NMR and SEC investigations, it is demonstrated that the SEC secondary peak originally believed to be the high molecular weight “daughter” polymer actually corresponds to nanoparticles containing the daughter polymer. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1590–1600     

Development of catalyst‐transfer condensation polymerization. Synthesis of π‐conjugated polymers with controlled molecular weight and low polydispersity

We describe the development of chain‐growth condensation polymerization for the synthesis of well‐defined π‐conjugated polymers via a new polymerization mechanism, catalyst‐transfer polymerization. We first studied the condensation polymerization of Grignard‐type hexylthiophene monomer with a Ni catalyst as a part of our research on chain‐growth condensation polymerization, and found that this polymerization also proceeded in a chain‐growth polymerization manner. However, the polymerization mechanism involving the Ni catalyst was different from that of previous chain‐growth condensation polymerizations based on substituent effects; the Ni catalyst catalyzed the coupling reaction of the monomer with the polymer, followed by the transfer of Ni(0) to the terminal C? Br bond of the elongated molecule. This catalyst‐transfer condensation polymerization is generally applicable for the synthesis of polythiophene with an etheric side chain and poly(p‐pheneylene), as well as for the synthesis of polyfluorene via the Pd‐catalyzed Suzuki–Miyaura coupling reaction. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 753–765, 2008     

Reactive polymer zwitterions: Sulfonium sulfonates

Sulfonium sulfonate, or sulfothetin, zwitterionic monomers were synthesized by ring‐opening of 1,3‐propanesultone with dialkyl sulfides containing styrenic or methacrylic moieties. Reversible addition‐fragmentation chain‐transfer polymerization of these monomers was achieved in water or trifluoroethanol, and the resulting polymers exhibited higher upper critical solution temperatures than the analogous sulfobetaine polymers. Unlike typical polymer zwitterions, these polymeric sulfothetins possess an inherent reactivity that proved tunable based on their chemical structures. This reactivity makes them amenable to post‐polymerization modification by nucleophilic dealkylation to rapidly access novel substituted polymers and gels. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 83–92     

Synthesis and characterization of stimuli‐responsive porous/hollow nanoparticles by self‐assembly of chitosan‐based graft copolymers and application in drug release

In this research, stimuli‐responsive porous/hollow nanoparticles were prepared by the self‐assembly method. First, chitosan‐graft‐poly(N‐isopropylacrylamide) (CS‐g‐PNIPAAm) copolymers were synthesized through polymerization of N‐isopropylacrylamide (NIPAAm) monomer in the presence of chitosan (CS) solution using ceric ammounium nitrate as the initiator. Then, the CS‐g‐PNIPAAm copolymers were dissolved in the acetic acid aqueous solution and heated to 40 °C to induce their self‐assembly. After CS‐g‐PNIPAAm assembled to form micelles, a cross‐linking agent was used to reinforce the structure to form nanoparticles. The molecular weight of grafted PNIPAAm on CS chains was changed to investigate its effect on the structure, morphology, thermo‐, and pH‐responsive properties of the nanoparticles. TEM images showed that a porous or hollow structure in the interior of nanoparticles was developed, depending on the medium temperature. The synthesized nanoparticles carried positive charges on the surface and exhibited stimuli‐responsive properties, and their mean diameter thus could be manipulated by changing the pH value and temperature of the environment. The nanoparticles showed a continuous release of the encapsulated doxycycline hyclate up to 10 days during an in vitro release experiment. These porous/hollow particles with environmentally sensitive properties are expected to be used in hydrophilic drug delivery system. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2377–2387, 2010