Layer‐by‐Layer Assembled Nanotubes as Biomimetic Nanoreactors for Calcium Carbonate Deposition

Enzyme‐loaded magnetic polyelectrolyte multilayer nanotubes prepared by layer‐by‐layer assembly combined with the porous template could be used as biomimetic nanoreactors. It is demonstrated that calcium carbonate can be biomimetically synthesized inside the cavities of the polyelectrolyte nanotubes by the catalysis of urease, and the size of the calcium carbonate precipitates was controlled by the cavity dimensions. The metastable structure of the calcium carbonate precipitates inside the nanotubes was protected by the outer shell of the polyelectrolyte multilayers. These features may allow polyelectrolyte nanotubes to be applied in the fields of nanomaterials synthesis, controlled release, and drug delivery.

     

Cinnamate‐functionalized poly(ester‐carbonate): Synthesis and its UV irradiation‐induced photo‐crosslinking

A functionalized cyclic carbonate monomer containing a cinnamate moiety, 5‐methyl‐5‐cinnamoyloxymethyl‐1,3‐dioxan‐2‐one (MC), was prepared for the first time with 1,1,1‐tri(hydroxymethyl) ethane as a starting material. Subsequent polymerization of the new cyclic carbonate and its copolymerization with L ‐lactide (LA) were successfully performed with diethyl zinc (ZnEt₂) as initiator/catalyst. NMR was used for microstructure identification of the obtained monomer and copolymers. Differential scanning calorimetry (DSC) was used to characterize the functionalized poly(ester‐carbonate). The results indicated that the copolymers displayed a single glass transition temperature (T_g) and the T_g decreased with increasing carbonate content and followed the Fox equation, indicative of a random microstructure of the copolymer. The photo‐crosslinking of the cinnamate‐carrying copolymer was also demonstrated. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 161–169, 2009     

Synthesis and properties of poly(carbonate‐urethane) consisting of alternating carbonate and urethane moieties

Poly(carbonate‐urethane) consisting of alternating carbonate and urethane moieties (poly(HC‐MDI)) was prepared by polyaddition of 4,4′‐diphenylmethane diisocyanate (MDI) and a monocarbonate diol bis(3‐hydroxypropyl)carbonate (HC), prepared by hydrolysis of a six‐membered spiroorthocarbonate 1,5,7,11‐tetraoxa‐spiro[5.5]undecane. The polyaddition proceeds without concomitant side reactions including carbonate exchange reaction and affords the desired poly(carbonate‐urethane). The hydrolysis and thermal behaviors of poly(HC‐MDI) were compared with those of the analogous polyurethane carrying no carbonate structure (poly(ND‐MDI)) prepared from MDI and 1,9‐nonanediol (ND). Although the glass transition behaviors are almost identical, poly(HC‐MDI) is less crystalline than poly(ND‐MDI). Poly(HC‐MDI) is more susceptible to hydrolysis than poly(ND‐MDI) probably due to the higher polarity and the lower crystallinity. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2802–2808, 2006     

Fabrication of Thermo‐Responsive Hybrid Hydrogels by In‐Situ Mineralization and Self‐Assembly of Microgel Particles

Summary: An in‐situ mineralization process in the presence of thermo‐responsive microgels leads to the formation of well‐defined hybrid materials. Experimental data suggest that control of the mineralization process in the presence of the microgels offers the possibility to obtain sub‐micrometer‐sized hybrid particles or macroscopic hybrid hydrogels. The rapid formation of CaCO₃ crystals in the microgel structure favors the preparation of the hybrid particles wherein inorganic crystals cover the shell layer of the microgel. The slow formation of CaCO₃ crystals leads to the simultaneous self‐assembly of the microgel particles on the bottom of the reaction vessel, and the formation of a physical network. It has been demonstrated that hybrid hydrogel materials with different calcium carbonate contents and temperature‐dependent swelling‐deswelling properties can be prepared.

Formation of a hybrid hydrogel by the vapor diffusion method.     

Differentiating calcium carbonate polymorphs by surface analysis techniques—an XPS and TOF‐SIMS study

Calcium carbonate has evoked interest owing to its use as a biomaterial, and for its potential in biomineralization. Three polymorphs of calcium carbonate, i.e. calcite, aragonite, and vaterite were synthesized. Three conventional bulk analysis techniques, Fourier transform infrared (FTIR), X‐ray diffraction (XRD), and SEM, were used to confirm the crystal phase of each polymorphic calcium carbonate. Two surface analysis techniques, X‐ray photoelectron spectroscopy (XPS) and time‐of‐flight secondary ion mass spectroscopy (TOF‐SIMS), were used to differentiate the surfaces of these three polymorphs of calcium carbonate. XPS results clearly demonstrate that the surfaces of these three polymorphs are different as seen in the Ca(2p) and O(1s) core‐level spectra. The different atomic arrangement in the crystal lattice, which provides for a different chemical environment, can explain this surface difference. Principal component analysis (PCA) was used to analyze the TOF‐SIMS data. Three polymorphs of calcium carbonate cluster into three different groups by PCA scores. This suggests that surface analysis techniques are as powerful as conventional bulk analysis to discriminate calcium carbonate polymorphs. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis and properties of vinyl‐terminated and silicon‐containing polysulfones and polyketones

4‐Fluorophenylsulfonylphenyl‐terminated polysulfone and 4‐fluorobenzoylphenyl ketone were prepared with bisphenol A and an excess of bis‐(4‐fluorophenyl)sulfone or 4,4′‐difluorobenzophenone, respectively, at 160 °C using potassium carbonate in N,N‐dimethylacetamide. The resulting polymers were reacted with 4‐hydroxystyrene to synthesize vinyl‐terminated polysulfones and ketones. The silicon‐containing polysulfones and ketones were prepared from the vinyl‐terminated polymer precursor and various H‐functional silanes or siloxanes. The synthesis of silicon‐containing polymers was achieved by hydrosilation with a rhodium catalyst. It was shown that the hydrosilation reaction proceeds with 55:45 chemoselectivity. The resulting polymers were investigated by ¹H NMR spectroscopy, DSC, and thermogravimetric analysis. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2937–2942, 2001     

PVDF membrane formation by diffusion‐induced phase separation‐morphology prediction based on phase behavior and mass transfer modeling

The equilibrium phase behavior of water (nonsolvent)‐DMF (solvent)‐PVDF system at 25°C was investigated via both theoretical and experimental approaches. Using binary interaction parameters, χ_ij, obtained previously, the theoretical phase boundaries were computed and were found to match closely the measured binodal and crystallization‐induced gelation data. Membranes were prepared using the isothermal immersion‐precipitation processes in various dope and bath conditions. The formed membranes demonstrated a broad spectrum of morphologies: At one extreme, asymmetric structure was obtained featuring a continuous tight skin and a sublayer composed of parallel macrovoids and cellular pores; at the other limit, skinless microporous membrane was produced with spherical particles packed into a bi‐continuous structure. The crystalline characters of PVDF gels and membranes were examined by small angle light scattering, scanning electron microscopy, and differential scanning calorimetry techniques. In addition, diffusion trajectories and concentration profiles in the membrane solution before precipitation were calculated for the immersion process. These results predicted reasonably the various morphologies observed in the membranes. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2079–2092, 1999     

Preparation of Dodecyl Dimethyl Benzyl Ammonium Bromide-Doped Cubic CaCO<Subscript>3</Subscript> with Antibacterial Properties

CaCl₂ encapsulated was placed in the hydrothermal reactor of an aqueous solution of Na₂CO₃ and dodecyl dimethyl benzyl ammonium bromide for synthesis of two samples of calcium carbonate by an improved hydrothermal method and one-pot method. Their crystal structure, morphology, chemical composition, and thermal stability of the synthesized samples of calcium carbonate were investigated by XRD, FTIR, SEM, EDS and TGDSC. The sterilization activity of the as-prepared samples was evaluated by killing of Sarcina lutea bacteria. The results indicated that the regular cube capsule-assisted calcium carbonate prepared by hydrothermal process was doped with dodecyl dimethyl benzyl ammonium bromide. Under the same condition, the spindle-shaped calcium carbonate synthesized the one-pot method was not doped with dodecyl dimethyl benzyl ammonium bromide. Among the samples of calcium carbonate, capsule-assisted calcium carbonate had shown better antibacterial effect for Sarcina lutea: in 48 h after its inhibition a zone diameter was 12.3 mm.     

Pendant cyclic carbonate‐polymer/Na‐smectite nanocomposites via in situ intercalative polymerization and solution intercalation

Nanocomposites of sodium smectite with polyether‐ and polystyrene‐containing pendant cyclic carbonates offer a novel approach to improving hydraulic barrier properties of Na‐smectite liners to saline leachates. The cyclic carbonate polyethers were prepared by cationic ring opening polymerization of a cyclic carbonate‐containing epoxide, whilst polystyrene polymers having pendant cyclic carbonate groups were obtained from radical photopolymerization of styrene. Na‐smectite nanocomposites of these polymers were formed via clay in situ polymerization and solution intercalation methods. X‐ray diffraction (XRD) and FT‐IR analysis confirmed that the polyether can be intercalated within the layers of smectite via in situ as well as solution intercalation of the pre‐formed polymer. The cyclic carbonate polyether nanocomposite was more resistant to leaching in 3M aqueous sodium chloride than its respective cyclic carbonate. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2421–2429     

Water‐based inorganic/polymer hybrid particles prepared via a multiple miniemulsion process

A universal method for the synthesis of water‐based inorganic–polymer hybrid particles was developed in which no organic solvent is required. To demonstrate the versatility of this process, zinc phosphate, calcium carbonate, and barium sulfate were chosen as different pigment examples which additionally can be utilized for functional coating applications. Furthermore, a complex polymeric composition based on epoxy–acrylic–styrene was chosen to illustrate the versatility from a soft matter point of view. The overall synthesis process was carried out by coemulsification of two inverse miniemulsions, containing two precursors, surrounded with a polymerizable continuous phase. This was then transferred to a direct miniemulsion by addition to a surfactant solution and subsequent homogenization followed by radical polymerization of the vinylic monomers. To our knowledge, this is the first work where a polymerizable continuous phase has been used in an inverse miniemulsion formation followed by transfer to a direct miniemulsion, followed by polymerization, so that the result is a water‐based dispersion. The resultant dispersion was characterized by dynamic light scattering; the particles were investigated via transmission electron microscopy with in situ determination of crystallinity using electron diffraction. Elemental analysis was also performed for the particles and the polymerized miniemulsions using X‐ray fluorescence and inductively coupled plasma‐optical emission spectroscopy, respectively. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis of fully lower‐rim,carbonate‐bridged calix[8]arenes and their curing behavior

Novel fully lower‐rim, carbonate‐bridged calix[8]arene derivatives were successfully synthesized in high yield by the condensation of p‐alkyl substituted calix[8]arenes with triphosgene. Different bases and catalysts were used for the preparation depending on the p‐alkyl substituted groups of the calix[8]arenes. The conformational features of the derivatives were examined by ¹H NMR analysis. Thermosetting formulations were prepared from a mixture of bisphenol A polycarbonate with calix[8]arene carbonate derivatives using sodium benzoate as a catalyst. Their crosslinking behaviors were studied using differential thermal/thermogravimetric analysis. No glass‐transition temperatures were observed after annealing at 280–300 °C. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1149–1155, 2001     

Near‐monodisperse,catalytically active,imidazole‐containing homooligomers: Synthesis by group transfer polymerization and solution characterization

Oligomers covering degrees of polymerization up to 23 of 2‐(1‐imidazolyl)ethyl methacrylate (ImEMA) were synthesized by group transfer polymerization (GTP) in propylene carbonate and tetrahydrofuran (THF). While GTP proceeds smoothly in propylene carbonate, polymerization in THF is accompanied by oligomer precipitation. The molecular weights (MWs) and molecular weight distributions (MWDs) of the oligomers were obtained by gel permeation chromatography (GPC) using acidic aqueous sodium nitrate as the eluent. Good control over the MW and small polydispersity indices (PDIs) were measured for the oligomers prepared in propylene carbonate but not in THF. The oligomers were evaluated for their ability to hydrolyze 4‐nitrophenyl acetate in aqueous solution. The hydrolytic activity increased with oligomer MW. The oligomer concentration‐ and substrate concentration‐dependencies of the initial hydrolysis rate were both found to be approximately first order. The hydrolytic activity increased with an increase in pH, manifesting the enhanced nucleophilicity and pronounced hydrophobicity of the unprotonated form of the repeating units. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1501–1512, 1999     

7Li NMR chemical shift titration and theoretical DFT calculation studies: solvent and anion effects on second‐order complexation of 12‐crown‐4 and 1‐aza‐12‐crown‐4 with Lithium cation in several aprotic solvents

⁷Li NMR titration was used to determine stepwise complexation constants for the second‐order complexation of lithium cation with 12‐crown‐4 in acetonitrile, propylene carbonate and a binary mixture of propylene carbonate and dimethyl carbonate. The anions used were perchlorate, hexaflurophosphate and trifluromethanesulfonate. A second ligand 1‐aza‐12‐crown‐4 was similarly investigated. The exchange between the free and complexed cation in these reactions is fast on an NMR timescale resulting in a single lithium peak which is a concentration‐weighted average of the free and bound species. Solvent effects show that the 1:1 complex is much more stable in acetonitrile than in propylene carbonate or in the propylene carbonate dimethyl carbonate mixture. Anion effects for a given solvent were small. Optimized geometries of the free ligands and the 1:1 and 1:2 (sandwich) metal–ligand complexes were predicted by hybrid‐density functional theory using the Gaussian 03 software package. Results were compared to literature values for 1:1 stability constants found by microcalorimetry for several of these systems and are found to be in good agreement. Although microcalorimetry only considered the formation of 1:1 complexes, ⁷Li NMR shows evidence that both 1:1 and 1:2 complexes should be considered. Copyright © 2009 John Wiley & Sons, Ltd.     

Alternating copolymerization of carbon dioxide and propylene oxide catalyzed by (R,R)‐SalenCoIII‐ (2,4‐dinitrophenoxy) and Lewis‐basic cocatalyst

A binary catalyst system of a chiral (R,R)‐SalenCo^III(2,4‐dinitrophenoxy) (salen = N,N‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐diphenylethylenediimine) in conjunction with (4‐dimethylamino)pyridine (DMAP) was developed to generate the copolymerization of carbon dioxide (CO₂) and racemic propylene oxide (rac‐PO). The influence of the molar ratio of catalyst components, the operating temperature, and reaction pressure on the yield as well as the molecular weight of polycarbonate were systematically investigated. High yield of turnover frequency (TOF) 501.2 h^?1 and high molecular weight of 70,400 were achieved at an appropriate combination of all variables. The structures of as‐prepared products were characterized by the IR, ¹H NMR, ¹³C NMR measurements. The linear carbonate linkage, highly regionselectivity and almost 100% carbonate content of the resulting polycarbonate were obtained with the help of these effective catalyst systems under facile conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5050–5056, 2007     

Preparation of poly(propylene‐co‐γ‐butyrolactone carbonate) and release profiles of drug‐loaded microcapsules

A new aliphatic poly(propylene‐co‐γ‐butyrolactone carbonate) (PPCG) was successfully synthesized through the copolymerization of carbon dioxide, propylene oxide (PO), and γ‐butyrolactone (GBL). GBL was inserted into the backbone of PO–CO₂. The glass transition of PPCG was as high as 16 °C, far higher than that (?1.5 °C) of poly(propylene carbonate) (PPC). The decomposition temperatures of PPCG and PPC were only slightly different. Because of the existence of the GBL ester unit, PPCG had stronger degradability than PPC in a pH 7.4 phosphate‐buffered solution. However, when the PO/GBL ratio increased beyond 5:2, the excessive amount of GBL was not added to the polymerization. PPCG and PPC microcapsules were prepared by the water‐in‐oil‐in‐water multiple‐emulsion method. Glucose was encapsulated. The PPCG microcapsules, about 2 μm in diameter, had smooth and spherical surfaces. The glucose release test revealed that the glucose release speed of the PPCG–glucose microcapsules was more than eight times faster than that of the PPC–glucose microcapsules in a pH 7.4 phosphate‐buffered solution. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2468–2475, 2005     

Solvent‐free synthesis of polyacrylamide by frontal polymerization

Polymerization and characterization of polyacrylamide prepared by frontal polymerization are described. Frontally polymerized polyacrylamide is imidized and crosslinked during polymerization. Imide formation was determined by elemental analysis. The addition of commercial polyacrylamide or barium carbonate to the monomer (acrylamide) and initiator (potassium persulfate) decreased the reaction temperature from 235 °C to < 100 °C, thereby reducing imide formation. The commercial polyacrylamide‐diluted product, frontally polymerized polyacrylamide‐diluted product, and the barium carbonate‐diluted product were characterized by IR, TGA, and elemental analysis. Molecular weights of barium carbonate‐diluted samples were determined by light scattering and found to be on the order of one million. Conversion of the barium carbonate‐diluted product was determined to be 76 ± 6%, independent of the amount of diluent over the range 0.8:1–1.5:1. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1129–1135, 2000     

Synthesis and characterization of poly(ethylene oxide‐co‐ethylene carbonate) macromonomers and their use in the preparation of crosslinked polymer electrolytes

Methacrylate‐functionalized poly(ethylene oxide‐co‐ethylene carbonate) macromonomers were prepared in two steps by the anionic ring‐opening polymerization of ethylene carbonate at 180 °C, with potassium methoxide as the initiator, followed by the reaction of the terminal hydroxyl groups of the polymers with methacryloyl chloride. The molecular weight of the polymer went through a maximum after approximately 45 min of polymerization, and the content of ethylene carbonate units in the polymer decreased with the reaction time. A polymer having a number‐average molecular weight of 2650 g mol^?1 and an ethylene carbonate content of 28 mol % was selected and used to prepare a macromonomer, which was subsequently polymerized by UV irradiation in the presence of different concentrations of lithium bis(trifluoromethanesulfonyl)imide salt. The resulting self‐supportive crosslinked polymer electrolyte membranes reached ionic conductivities of 6.3 × 10^?6 S cm^?1 at 20 °C. The coordination of the lithium ions by both the ether and carbonate oxygens in the polymer structure was indicated by Fourier transform infrared spectroscopy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2195–2205, 2006     

Collapse and swelling of poly(N‐isopropylacrylamide‐co‐sodium acrylate) copolymer brushes grafted on a flat SiO2 surface

Poly(N‐isopropylacrylamide‐co‐sodium acrylate) copolymer brushes grafted on SiO₂‐coated quartz crystal surface were prepared with a surface‐immobilized initiator. The collapse and swelling of the thermally sensitive copolymer brushes in water were studied with quartz crystal microbalance in situ. The frequency and dissipation changes with the temperature increasing in the range 20–38 °C indicate that the brushes undergo a continuous collapse transition. Our results show that the copolymer brushes collapse to a state where the brushes were prepared. A hysteresis was observed in the cooling process. Fourier transform infrared (FTIR) results revealed that the formation of some additional hydrogen bonds within the copolymer chains at their collapsed state is responsible for the hysteresis. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 770–778, 2006     

Synthesis of poly(isopropenylphenoxy propylene carbonate) and its facile side‐chain functionalization into hydroxy‐polyurethanes

4‐Isopropenyl phenol ( 4‐IPP ) is a versatile dual functional intermediate that can be prepared readily from bisphenol‐A ( BPA ). Through etherification with epichlorohydrin to the phenolic group of 4‐IPP , it can be converted into 4‐isopropenyl phenyl glycidyl ether ( IPGE ). On further reaction with carbon dioxide in the presence of tetra‐n‐butyl ammonium bromide ( TBAB ) as the catalyst, IPGE was transformed into 4‐isopropenylphenoxy propylene carbonate ( IPPC ) in 90% yield. Cationic polymerization of IPPC with strong acid such as trifluoromethanesulfonic acid or boron trifluoride diethyl etherate as the catalyst at ?40 °C gave a linear poly(isopropenylphenoxy propylene carbonate), poly( IPPC ), with multicyclic carbonate groups substituted uniformly at the side‐chains of the polymer. The cyclic carbonate groups of poly( IPPC ) were further reacted with different aliphatic amines and diamines resulting in formation of polymers with hydroxy‐polyurethane on side‐chains. Syntheses, characterizations of poly( IPPC ) and its conversion into hydroxy‐polyurethane crosslinked polymers were presented. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 802–808