2,4,6‐trichlorophenyl acrylate emulsion‐templated porous polymers (PolyHIPEs). Morphology and reactivity studies

A series of monolithic crosslinked polymers with 2,4,6‐trichlorophenyl acrylate as a reactive component was prepared by free radical polymerization of the internal phases of high internal phase emulsions (HIPEs). The volume ratio of water to oil phase (void volume; 60–90%), crosslinker type (divinylbenzene or ethylenglycol dimethacrylate) and quantity (30–50 mol %) and type of porogenic solvent (chlorobenzene, toluene, chloroform, dichloroethane) were altered to study these effects on the structure and reactivity of the monolithic polymers. The polymer supports were characterized by scanning electron microscopy (SEM), FTIR spectroscopy, elemental analysis and mercury intrusion porosimetry. SEM images revealed an open cellular structure with voids between 1 and 12 μm and window sizes between 0.3 and 3 μm. The porogen had an influence on the surface area, being larger with added porogen and the influence being highest with toluene. Adding toluene also influenced the void size, increasing the average diameter from ～2 μm (no porogen) to ～12 μm (added toluene). Monolithic supports were functionalized by reaction of the ester moieties with tris(2‐aminoethyl)amine derivative and by hydrolysis of the ester groups to carboxylic acids. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4043–4053, 2007     

Optimized peptide functionalization of thiol‐acrylate emulsion‐templated porous polymers leads to expansion of human pluripotent stem cells in 3D culture

Highly porous polymers produced by polymerization of the continuous phase of a high internal phase emulsion have been developed as scaffolds for 3D culture of human pluripotent stem cells. These emulsion‐templated polymerized high internal phase emulsion (polyHIPE) materials have an interconnected network of pores that provide support for the cells, while also allowing both cell ingress and nutrient diffusion. Thiol‐acrylate polyHIPE materials were prepared by photopolymerization, which, due to a competing acrylate homopolymerization process, leads to a material with residual surface thiols. These thiols were then used as a handle to allow postpolymerization functionalization with both maleimide and a maleimide‐derivatized cyclo‐RGDfK peptide, via Michael addition under benign conditions. Functionalization was evaluated using an Ellman's colorimetric assay, to monitor the residual thiol concentration, and X‐ray photoelectron spectroscopy. Maleimide was used as a model molecule to optimize conditions prior to peptide‐functionalization. The use of triethylamine as a catalyst and a mixed ethanol‐aqueous solvent system led to optimized reaction between surface‐bound thiols and maleimide. Peptide‐functionalized materials showed improved attachment and infiltration of human pluripotent stem cells over 7 days, demonstrating their promise as a scaffold for 3D stem cell culture and expansion. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1974–1981     

Preparation of epoxy‐functionalized polystyrene/silica core–shell composite nanoparticles

Epoxy‐functionalized polystyrene/silica core–shell composite nanoparticles were prepared by the postaddition of glycidyl methacrylate (GMA) via emulsion polymerization. The outermost shell of obtained multilayered core–shell particles was made up of poly(glycidyl methacrylate) (PGMA). A semicontinuous process involving the dropwise addition of GMA was used to avoid demulsification of the emulsion system. The amount of grafted PGMA was quantified by Fourier transform infrared spectroscopy and was altered in a wide range (1–50 wt % to styrene). The binding efficiency was usually high (ca. 90%), indicating strong adhesion between the silica core and the polymer shell. There were approximately four or five original silica beads, which formed a cluster, per composite of nanoparticles whose size was about 60–70 nm. Other main factors of polymerization conditions including the amounts of sodium dodecyl sulfonate and silica are also discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2253–2262, 2004     

Hydrazine‐functionalized latexes

The noncommercial functional monomer 4‐vinylbenzyl hydrazine (VBH) was synthesized and subsequently copolymerized with styrene (St) by means of different batch and semicontinuous seeded emulsion polymerization processes, so as to obtain hydrazine‐functionalized nanoparticles. The effect of pH, surfactant and initiator amounts, ratio VBH/St, reaction temperature, and ratio acetone/water were studied. Due to the amphiphilic character of VBH at acid pH, the hydrazine groups of the functionalized comonomer were masked with acetone to form hydrazone groups. Secondary nucleations were avoided by using the protected VBH comonomer; however, a decreased radical efficiency achieving limited conversion was observed. Controlling the cationic initiator concentration, complete conversions together with the neat growth of the seed particles were obtained in the semicontinuous seeded emulsion polymerization of styrene and VBH protected with acetone. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6201–6213, 2009     

A degradable,porous, emulsion‐templated polyacrylate

A polyHIPE is a highly porous, emulsion‐templated polymer synthesized by polymerizing a monomer and a crosslinking comonomer in the continuous phase of a high‐internal phase emulsion (HIPE). The synthesis of degradable polyHIPE could be of interest for biomedical applications such as tissue engineering scaffolds. In this research, a poly(ε‐caprolactone) (PCL) oligomer with terminal vinyl groups was used as the crosslinking comonomer for a polyHIPE based on t‐butyl acrylate (tBA). The porous structure, properties, water absorption, and hydrolytic degradation of the polyHIPE were investigated. The polyHIPE containing 50 wt % PCL exhibited very large voids, 1 to 3 mm in diameter that resulted from the destabilization of the HIPE on addition of PCL, making the polyHIPE more suitable for tissue engineering applications. The relatively flexible PCL enhanced segmental mobility, yielding two glass transition temperatures and a significant reduction in modulus. When exposed to a 3 M aqueous solution of NaOH, the t‐butyl groups underwent hydrolysis and the PCL underwent degradation, rapidly leading to the complete disintegration of the macromolecular structure. The tBA‐based polyHIPE containing 50 wt % PCL exhibited enhanced cell adhesion, penetration, and growth indicating that it is a suitable candidate for further research and development. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009     

Preparation of macroporous hydrophobic materials filled with aligned porous hydrophilic domain via emulsion‐templated and unidirectional freezing technique

A new class of porous materials, having hydrophobic scaffold embedded with aligned porous hydrophilic domains, was in situ fabricated through combination of emulsion‐templated method and unidirectional freezing technique. A water‐in‐oil high internal phase emulsion (HIPE) was prepared with the mixture of styrene and divinylbenzene as continuous phase and a poly(vinyl alcohol) (PVA) aqueous solution as dispersed phase. After polymerization of the continuous phase and subsequently unidirectional freezing, the dispersed phase, a macroporous poly(styrene/divinylbenzene) embedded with an aligned PVA domain, was obtained. The effects of the polymerization temperature, PVA concentration, and freezing rate on these porous materials were investigated. It was found that the PVA domain size and the aligned channel size were dependent on the polymerization temperature, the PVA concentration, and freezing rate. The fabrication method in this work, combining of unidirectional freezing and emulsion template, not only allows to prepare hydrophobic–hydrophilic polyHIPEs having a sea island structure but also dramatically improves the stiffness and specific surface area of the resulting polyHIPEs. Copyright © 2017 John Wiley & Sons, Ltd.     

Preparation of emulsion‐templated fluorinated polymers and their application in oil/water separation

A series of emulsion‐templated fluorinated polymers (polyHIPEs) were first synthesized with introducing 2‐(perfluorohexyl)ethyl methacrylate (PEM) to the external phase of water‐in‐styrene high internal phase emulsion (HIPE) templates. The morphology (i.e., void size and its distribution) of these porous materials could be tuned simply by changing PEM and/or surfactant amount. The synergistic effect between the surface chemistry and surface architecture allowed the polyHIPEs to possess hydrophobicity with a water contact angle of 151°. The superhydrophobicity and oleophilicity of the polyHIPEs, together with their highly open porous structure, make the material a very competitive candidate as a filtration material for oil/water separation in practice with the efficiency of separating dichloromethane from the oil/water mixture of 95%. Such oil/water separating capacity was maintained after 10 cycles of filtration of oil/water, indicating the cyclic usage of the polyHIPE is feasible. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1508–1515     

Modification of carboxyl‐functionalized single‐walled carbon nanotubes with biocompatible,water‐soluble phosphorylcholine and sugar‐based polymers: Bioinspired nanorods

We report here the successful functionalization of single‐walled carbon nanotubes with bioinspired sugar and phosphocholine polymeric structures via surface‐initiated atom transfer radical polymerization. The surface‐polymer‐coated carbon nanotubes have been systematically analyzed by Raman, infrared, ultraviolet–visible, and nuclear magnetic resonance spectroscopy and high‐resolution transmission electron microscopy, which give strong evidence of successful functionalization. The successful aqueous dispersion of the functionalized carbon nanotubes also indicates that functionalization has been achieved. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6558–6568, 2006     

Diene‐based polymer nanoparticles: Preparation and direct catalytic latex hydrogenation

The diene‐based polymer nanoparticles represented by poly(butadiene‐co‐acrylonitrile) were prepared in the semibatch emulsion polymerization system using Gemini surfactant (GS) trimethylene‐1,3‐bis(dodecyldimethylammonium bromide) as the emulsifier. The nanoparticles within the range of 17–54 nm were achieved with narrow molecular weight and particle size distributions. A spherical morphology was observed for the produced nanoparticles. The effects of GS concentration on the particle size, molecular weight, polymerization conversion and solid content, and composition of copolymer were investigated. The semibatch process using monomeric and conventional surfactant sodium dodecyl sulfate (SDS) was compared. At the second stage of this study, the prepared unsaturated nanoparticles were employed as the substrates for the latex hydrogenation in the presence of Wilkinson's catalyst, that is, RhCl(P(C₆H₅)₃)₃. The effects of the particle size and catalyst concentration on the latex hydrogenation rate were investigated. The particle size is found to have a significant effect on the reaction rate. When the 17‐nm nanoparticles were used as the substrates, a high conversion of 95 mol % was obtained within 18 h using only 0.1 wt % RhCl(P(C₆H₅)₃)₃. The latex hydrogenation process was completely free of organic solvents. The present synthesis and following “green” hydrogenation process can be extended to latices made from semibatch emulsion containing other diene‐based polymers. This study shows great promise for decreasing the demanded quantity of expensive catalyst and eliminating the organic solvent in the hydrogenation process. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Amphiphilic mesogen‐jacketed liquid crystalline polymers: Design,synthesis, and self‐assembly behaviors

We synthesized a series of amphiphilic mesogen‐jacketed liquid crystalline (LC) polymers with a biphenyl side‐chain mesogen containing a carboxylic acid group on one side and an octyloxy group on the other, and the number of methylene units between the biphenyl core and the exterior carboxylic acid group was varied to adjust the mesophases and the amphiphilic nature. The polymers were obtained through conventional radical polymerizations and characterized by a combination of different techniques such as thermogravimetric analysis, differential scanning calorimetry, polarized light microscopy, and X‐ray scattering. The results revealed that the polymer without any methylene spacer, POBP‐0C, did not exhibit LC properties while POBP‐1C (n = 1) and POBP‐7C (n = 7) formed double layer smectic A (S_A) phases. The hydrogen bonding among the carboxylic acid groups and the segregation between the carboxylic acid groups and the alky chains played important roles in forming the mesophases. In addition, the solution self‐assembly behaviors were also preliminarily investigated through the fluorescent probe technique and transmission electron microscopy, and vesicles with uniform sizes were observed. The weak hydrophilicity and large degree of freedom of the carboxylic acid group and the relative rigidity of the polymer chain due to the “jacketing” effect were responsible for the formation of the structures. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Core‐shell type dually fluorescent polymer nanoparticles for ratiometric pH‐sensing

The synthesis and pH‐sensing properties of fluorescent polymer nanoparticles (NPs) in the 20 nm diameter range with a sensitive dye covalently attached to the particle surface and a reference dye entrapped within the particle core are presented. Fluorescein‐functionalized NPs were readily obtained by conjugation of fluorescein isothiocyanate (FITC) to amine‐coated crosslinked polystyrene‐based nanoparticles prepared by microemulsion polymerization followed by postfunctionalization. This all water‐based method gave access to stable aqueous suspensions of pH‐sensing fluorescent NPs. The encapsulation of the insensitive reference fluorescent dye (1,9‐diphenylanthracene, DPA) was then conveniently achieved by soaking leading to dual fluorescent NPs containing about 20 DPA and 55 fluorescein, as deduced from spectroscopic analyses. This core‐shell type architecture maximizes the interactions of the sensing dye with the medium while protecting the reference dye. The variations of the ratio of the fluorescence emission intensities of the sensitive dye (fluorescein) to the reference dye (DPA) with pH show that the dual fluorescent NPs act as a ratiometric pH sensor with a measuring range between pH 4 and pH 8. This pH nanosensor was found to be fast, fully reversible, and robust without any leaching of dye over a long period of time. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6206–6213, 2008     

Preparation of polymer/silica composite nanoparticles bearing carboxyl groups on the surface via emulsifier‐free emulsion copolymerization

Polymer/silica organic/inorganic composite nanoparticles bearing carboxyl groups on the surface were prepared via the emulsifier‐free emulsion copolymerization of methyl methacrylate and sodium methacrylate (NaMA). Carboxyl groups were generated by the addition of hydrochloric acid at the end of the copolymerization. Two methods of NaMA addition were studied: batch and two‐stage procedures. The batch procedure allowed only a limited number of carboxyl groups to effectively bond to the composite nanoparticles. In contrast, the number of carboxyl groups could be altered over a wide range with the two‐stage procedure. Fourier transform infrared spectroscopy and chemical titration were independently used to quantify the number of carboxyl groups, giving values close to each other and to the feed. A kinetic study indicated that the copolymerization followed a mechanism different than that found earlier. The average size of the composite nanoparticles was approximately 40 nm, as measured by both transmission electron microscopy (TEM) and laser scattering, and their polydispersity index was close to 1, indicating a fairly narrow size distribution. TEM photographs of the composite nanoparticles showed a multilayered core–shell structure with one silica bead as the core and with poly(methacrylate acid) as the outmost shell. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2826–2835, 2005     

A visible light responsive azobenzene‐functionalized polymer: Synthesis,self‐assembly,and photoresponsive properties

A novel visible light responsive random copolymer consisting of hydrophobic azobenzene‐containing acrylate units and hydrophilic acrylic acid units has been prepared. The azobenzene molecule bearing methoxy groups at all four ortho positions is readily synthesized by one‐step conversion of diazotization. The as‐prepared polymer can self‐assemble into nanoparticles in water due to its amphiphilic nature. The tetra‐o‐methoxy‐substituted azobenzene‐functionalized polymer can exhibit the trans‐to‐cis photoswitching under the irradiation with green light of 520 nm and the cis‐to‐trans photoswitching under the irradiation with blue light of 420 nm in both solution and aggregate state. The morphologies of the self‐assembled nanoparticles are revealed by TEM and DLS. The controlled release of loaded molecules from the nanoparticles can be realized by adjusting pH value since the copolymer possesses pH responsive acrylic acid groups. The fluorescence of loaded Nile Red in the nanoparticles can be tuned upon the visible light irradiation. The reversible photoswitching of the azobenzene‐functionalized polymer under visible light may endow the polymer with wide applications without using ultraviolet light at all. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2768–2775     

Long‐chain branched ROMP polymers

This article describes the construction of branched ROMP‐polymer architectures via polycondensation of AB_n‐type macromonomers. For this convergent strategy, a polymer was synthesized that carries several hydroxyl‐groups along the polymer chain and one carboxylic acid group at the chain end. An esterification reaction between these functional groups yielded long‐chain branched polymers. The polymers were analyzed by NMR and SEC to monitor the condensation reaction. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009     

Preparation,morphology, and biolabeling of fluorescent nanoparticles based on conjugated polymers by emulsion polymerization

Novel nanoparticles based on conjugated polymer with good fluorescent properties were synthesized by Suzuki coupling reaction using certain surfactants as one kind of special emulsion polymerization. The luminescent properties of the prepared nanoparticles could be controlled by selecting different monomers. Without using substances comprising any heavy metal element, these fluorescent nanoparticles show very good biocompatibility with cells, thus showing potential applications in cell biolabeling, drug delivery tracing, organic light‐emitting diodes, flat displays, and other areas. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis of novel dithienothiophene‐ and 2,7‐carbazole‐based conjugated polymers and H‐bonded effects on electrochromic and photovoltaic properties

Three kinds of dithienothiophene/carbazole‐based conjugated polymers ( P1–P3 ), which bear acid‐protected and benzoic acid pendants in P2 and P3 , respectively, were synthesized via Suzuki coupling reaction. Interestingly, P1 – P3 exhibited reversible electrochromism during the oxidation processes of cyclic voltammogram studies, and P3 (with H‐bonds) revealed the best electrochromic property with the most noticeable color change. According to powder X‐ray diffraction (XRD) analysis, these polymers exhibited obvious diffraction features indicating bilayered packings between polymer backbones and π‐π stacking between layers in the solid state. Compared with the XRD data of P2 (without H‐bands), H‐bonds of P3 induced a higher crystallinity in the small‐angle region (corresponding to a higher ordered bilayered packings between polymer backbones), but with a similar crystallinity in the wide angle region indicating a comparable π‐π stacking distance between layers. Moreover, based on the preliminary photovoltaic properties of PSC devices ( P1 – P3 blended individually with PCBM acceptor in the weight ratio of 1:1), P3 (with H‐bonds) possessed the highest power conversion efficiency of 0.61% (with J_sc = 2.26 mA/cm², FF = 29.8%, and V_oc = 0.9 V). In contrast to P2 (without H‐bands), the thermal stability, crystallinity, and electrochromic along with photovoltaic properties of P3 were generally enhanced due to its H‐bonded effects. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Organic solvent‐free catalytic hydrogenation of diene‐based polymer nanoparticles in latex form: Part I. Preparation of nano‐substrate

Poly(butadiene‐co‐acrylonitrile) (NBR) nanoparticles were synthesized in a semibatch emulsion polymerization system using Gemini surfactant trimethylene‐1,3‐bis (dodecyldimethylammonium bromide), referred to as Gemini‐type surfactant (GS) 12‐3‐12, as the emulsifier. In this polymerization system, an enhanced decomposition rate of initiator ammonium persulfate was achieved even under the low temperature of 50 °C which is attributed to the acidic initiation environment provided using GS 12‐3‐12. The microstructure and copolymer composition of the polymer nanoparticles were characterized by Fourier‐transformed infrared and ¹H nuclear magnetic resonance spectroscopy. The effects of the surfactant concentration on the particle size, zeta potential, polymerization conversion, copolymer composition, molecular weight, and glass transition temperature (T_g) were investigated. It was found that the particle diameter can be controlled by the surfactant concentration and monomer/water ratio and particle sizes below 20 nm can be reached. The obtained latex particles exhibit a spherical morphology. A kinetic study of the copolymerization reaction was carried out, which indicated that an azeotropic composition was produced. The synthesized fine NBR nanoparticles can be employed as the nano substrate for a subsequent hydrogenation process so as to overcome the challenge involved in the field of latex hydrogenation of polymers, which can be found in a related report: Organic Solvent‐Free Catalytic Hydrogenation of Diene‐based Polymer Nanoparticles in Latex Form: Part II. Kinetic Analysis and Mechanistic Study. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and proton conductivity studies of polystyrene‐based triazole functional polymer membranes

In this study, poly(vinylbenzylchloride) (PVBC) was produced by free‐radical polymerization of 4‐vinylbenzylchloride, and then it was functionalized with 3‐amino‐1,2,4‐triazole (ATri) and 1H‐1,2,4‐triazole (Tri). The composition of the polymers was verified by elemental analysis, and the structure was characterized by Fourier transform infrared and ¹³C‐nuclear magnetic resonance spectra. PVBC was modified by ATri with 68% and Tri with 50% yield. The polymers were doped with trifluoromethanesulfonic acid (TA) at various molar ratios, X = 0.5, 1, 2, and 3 with respect to aminotriazole and triazole units. Proton transfer from TA to the triazole rings was proved with Fourier transform infrared spectroscopy. Thermogravimetric analysis showed that the samples are thermally stable up to approximately 200 °C. Differential scanning calorimetry results illustrated the homogeneity of the materials. Under anhydrous conditions, PVBCATri3TA and PVBCTri3TA showed highest proton conductivity of 0.086 and 0.042 S/cm, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010