Modified Poly(2,6-dimethyl-1,4-phenylene ether)s Prepared by Redistribution

Some new macroinitiators (5) containing azo and peroxy groups were synthesized by transformation of esters of poly(ethylene glycol) (1) (PEG) of different molecular weight with hydroxyl end groups and an azo group in the middle into the corresponding polymers with tert‐butylperoxycarbonyl end groups by reaction with terephthaloyl chloride and subsequently with tert‐butyl hydroporoxide. Decomposition in the presence of styrene at 60°C or with 3,6,9‐triazaun‐decane‐1,11‐diamine in presence of methyl methacrylate gave the corresponding ABA block copolymer 6 and the ABBA block copolymer 7, respectively. Both block copolymers were used as polymeric initiators. The ABCBA block copolymer 8 was synthesized from 6 and methyl methacrylate or from 7 and styrene by thermally induced polymerization at 80°C. The resulting block copolymers were separated from the homopolymers by selective solvent extraction and characterized by spectroscopic and fractional precipitation methods.

We have synthesized and characterized a new family of low melting all‐aromatic ester‐based liquid crystal oligomers end‐capped with reactive phenylethynyl end groups. In a consecutive, high‐temperature step, the reactive end groups were thermally activated and polymerization was initiated. This reactive oligomer approach allows us to synthesize liquid crystal thermosets with outstanding mechanical and thermal properties, which are superior to well‐known high‐performance polymers such as PPS and PEEK. We have modified an intractable LC formulation based on hydroquinone and terephthalic acid, with Mn = 1000, 5000, and 9000 g mol−1, and varied the backbone composition using isophthalic acid, resorcinol, 4‐hydroxy‐benzoic acid, 6‐hydroxy‐2‐naphthoic acid, and chlorohydroquinone. All fully cured polymers showed glass transition temperatures in the range of 164–275 °C, and high storage moduli at room temperature (∼ 5 GPa) and elevated temperature (∼ 2 GPa at 200 °C). All oligomers display nematic mesophases and in most cases, the nematic order is maintained after cure. Rheology experiments showed that the phenylethynyl end group undergoes predominantly chain extension below 340 °C and crosslinking above this temperature. Highly aligned fibers could be spun from the nematic melt, and we found that the order parameter 〈P2〉 was not affected by the chain extension and crosslink chemistry. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1368–1380, 2009

The surface compositions of poly(styrene-b-ethylene oxide) and poly(styrene-g-ethylene oxide) films were found to be largely determined by the nature of the poly(ethylene oxide) (PEO) chain ends. Angle-dependent X-ray photoelectron spectroscopy revealed that polystyrene (PS) dominated the surfaces of the copolymers having PEO chain ends terminated by hydroxyl groups (SEO). Also, the PEO content decreased with decreasing sampling depth. In contrast, the surface regions of the corresponding copolymers having fluorinated PEO chain ends (fSEO) were dominated by PEO, and the PEO content increased with decreasing sampling depth. The fluorine content of fSEO also increased with decreasing sampling depth, indicating that the fluorinated chain ends were segregated at the outermost surface. The studied fSEO block copolymer seemed to have a higher surface concentration of fluorinated chain ends than the fSEO graft copolymers. Although it is likely that the fSEO surfaces were fully covered by fluorinated chain ends, the advancing water contact angles on fSEO films were markedly lower than on the corresponding SEO films. Moreover, low contact angles were retained even after prolonged annealing of the fSEO films in a vacuum. The surface behavior of BEO may be explained by the presence of flexible, fluorinated PEO chain ends, providing a highly dynamic surface. When fSEO films are immersed in water, the surfaces can rapidly restructure and expose PEO.

Acetal-poly(ethylene glycol)/poy[(2-N,N-dimethylaminoethyl) methacrylate] (acetal-PEG/ PAMA) block copolymer was prepared via an oxianionic polymerization technique, which was established by our laboratory. The acetal-end group was converted to an aldehyde group by an acidic hydrolysis reaction, followed by the installation of biotin moiety at the end of the PEG chain via a reductive amination reaction of biocytin hydrazide. The biotin-PEG/PAMA block copolymer thus prepared was mixed with CdSe/ZnS nano-particles (QD) in aqueous media. The obtained polymer-QD complex showed extremely high dispersion stability even in the physiological saline condition. The adsorbed biotin-PEG/PAMA block copolymer on the QD formed the tethered chain fashion on the surface to improve the dispersion stability by the steric factor of the tethered chains. Since the PEG chain end on the QD surface possessed biotin moiety, it could be utilized for not only immunohistochemistry but also various other biological applications.

Our group has investigated the incorporation of proteins in fibers by two approaches. One involves physical encapsulation of proteins in the bulk of ultrafine and porous fibers and the other bound proteins to fiber surfaces with reactive spacers and functional grafts. This paper reports two examples from the second approach. Both involve the addition of covalently bonded polymeric chains to ultra-fine cellulose fiber surfaces. One tethers enzyme proteins by covalently bonds via amphiphilic PEG spacers that carry reactive end groups. The other adds polyelectrolyte PAA grafts that are sufficiently polar to attract enzymes via secondary forces. Both surface polymer systems are compatible with aqueous and organic media. Lipase (E.C. 3.1.1.3, from Candida rugosa) enzyme was used. PEG was introduced by reacting cellulose with PEG diacylchloride followed by amide covalent bond formation between COOH of PEG and amine (NH 2 ) of the lipase. PAA (0.76-40.9 mmol of COOH per g cellulose) was grafted via ceric ion initiated polymerization. On the PEG attached cellulose, reactive COOH end groups ranging from 0.2 to 1.0 mmol per g cellulose. The adsorbed lipase on the PAA grafted cellulose fibers exhibited significantly higher immobilization efficiency, i.e., up to 391 Unit/mmol COOH, than the covalently bound lipase via PEG spacers. The immobilized lipases via both methods possessed much superior retention of catalytic activity following exposure to hydrocarbons, including cyclohexane, toluene, and hexane, than the free lipase. The covalently bound lipase exhibited significantly higher catalytic activity retention levels at elevated temperatures than the adsorbed and free form. In addition, both adsorbed and covalently bound lipases can be repeatedly used for 4 cycles.

Well-defined poly(vinyl acetate)-block-polystyrene (PVAc-b-PSt) block copolymers were successfully synthesized by a combination of cobalt-mediated radical polymerization (CMRP) and reversible addition−fragmentation chain transfer (RAFT) polymerization. PVAc and PVAc-b-PSt (with an average PSt repeating unit of 2 or 6) were first synthesized via CMRP with cobalt(II) acetylacetonate as a regulating agent. The cobalt complexes attached to their ω chain ends were modified into a phenyl dithioester group by reacting with bis(thiobenzoyl) disulfide, producing PVAc and PVAc-b-PSt macro-chain-transfer agents (PVAc-CTA and PVAc-PSt-CTA), respectively. The RAFT polymerization of styrene with PVAc-CTA or PVAc-PSt-CTA was conducted in N,N-dimethylformamide at 80 °C. PVAc-b-PSt block copolymers synthesized with PVAc-PSt6-CTA (with an average PSt repeating unit of 6) exhibited narrowest molecular weight distributions (Mw/Mn = 1.28−1.30) even at high conversions. The PVAc-b-PSt block copolymer (Mn(GPC) = 21 000 g/mol, M...

A straightforward transformation protocol combining two distinct living polymerization methods for the controlled synthesis of block copolymers is described. In the first step, bromo-terminated poly(methyl methacrylate) is prepared by atom transfer radical polymerization (ATRP). Then, a bromide end group is substituted with a triphenylmethyl (trityl) functionality under visible light irradiation using dimanganese decacarbonyl (Mn2 (CO)10 ) photochemistry. The resulting polymers with trityl end groups are used as macroiniferter for the polymerization of styrene and tert-butyl acrylate (tBA) to yield desired block copolymers with narrow molecular weight distribution. Moreover, the amphiphilic copolymers with acrylic acid functionalities are obtained by the hydrolyzation of poly(tert-butyl acrylate) containing block copolymers with trifluoroacetic acid.

Block copolymer (BCP) thin films with lamellar nanostructures oriented perpendicular to the substrate surface offer a potential alternative to photolithography for patterning nanoscale features. Additionally, molecular cyclization has been shown to reduce BCP feature sizes and improve thin film stability. However, control over the orientation of cyclic BCP lamellae is also needed for lithography. Here, we use dissipative particle dynamics (DPD) simulations to compare the stability of vertical versus horizontal lamellae formed by a linear BCP and two cyclic BCP analogues. To mimic thin film experiments, BCP chains are confined between a substrate and a fluid “gas” of DPD beads. When the surface interactions are non-preferential, both linear and cyclic BCPs form vertical lamellae. As the surface preference for one of the BCP blocks is increased, the polymers eventually reorient parallel to the substrate. The transition to a horizonal orientation occurred at lower surface preference for the cyclic BCPs, suggesting that the substrate neutrality condition for obtaining vertical lamellae is less stringent for linear BCPs than for cyclic BCPs. Analysis of chain orientations in the disordered phase reveals that the linear BCP has a larger fraction of chains aligned parallel to the substrate compared to the two cyclic BCPs, most likely due to the accumulation of chain ends near the surface. We believe that chains oriented parallel to the substrate play a key role in establishing the sensitivity of vertical lamellae formation on a preferential substrate. • DPD simulation of linear and cyclic block copolymer thin films • Linear block copolymers form more stable vertical lamellae than cyclic block copolymers • Orientation stability is related to polymer conformation at the substrate interface

One-pot synthesis of block copolymer dispersant by ICAR ATRP with ppm copper catalyst and the dispersibility on pigment

Membrane properties of A-B-A type block copolymer consisting of poly(γ-benzyl- l-glutamate) as the a component and polyisoprene as the B component

Self-assembling amphiphilic ABA triblock-copolymers, forming vesicular structures in
\naqueous solutions were the core material used in this thesis. The interest in amphiphilic blockcopolymers
\nresides basically in their improved characteristics in comparison to low molecular
\nweight amphiphiles, such as higher mechanical stability. Moreover, the polymer brush coating
\nof liposome-polymer hybrids (Stealth liposomes) is known to be effective on reducing uptake by
\nreticuloendothelial system (RES). This led to the idea of avoiding the use of lipids at all in these
\nstructures and work with self-assembling polymers. This has been done in our group through
\nthe use of an ABA amphiphilic triblock-copolymer, consisting of poly(2-methyl-2-oxazoline)-bpoly(
\ndimethylsiloxane)-b-poly(2-methyl-2-oxazoline) (PMOXA-PDMS-PMOXA), which surface
\ncontains a hydrophilic polymer with similar characteristics to poly(ethylene glycol). These two
\nadvantages of amphiphilic polymer vesicles, i.e. higher stability and the ability to avoid reticuloendothelial
\nuptake led to two main research interests which were addressed in this work: the
\nuse of nanocarriers based on synthetic self-assembling polymers as active targeting drug delivery
\nsystems and the immobilization of vesicles on surfaces.
\nBoth research topics shared the need to attach the polymer vesicles via docking sites.
\nTo address this a series of ABA triblock-copolymers were synthesized and functionalized to
\npromote their interaction either with other molecules or with surfaces. The synthesis of the
\npolymers was carried out via cationic ring opening polymerization of 2-methyl-2-oxazoline departing
\nfrom a telechelic poly(dimethylsiloxane). Langmuir films proved the surface activity of
\nthe amphiphilic polymers obtained. From the functionalization point of view, biotinylated blockcopolymers
\nproved to be the most versatile modification, through the use of the wide spread
\nbiotin-streptavidin specific interaction. Vesicles were prepared by already stablished methods
\n(solvent injection extrusion method) and new developed ones (direct dissolution), and were
\ncharacterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), and
\nfluorescence correlation spectroscopy (FCS). Moreover, the density of the vesicles was determined
\nby ultracentrifugation techniques.
\nTo obtain active targeting drug-delivery systems, ligands were introduced onto the
\nnanocontainer surface via coupling with streptavidin to the biotin moieties present on the nanocontainers
\nsurface. In vitro studies were performed to investigate the interactions of these
\nligand-functionalized nanocontainers with cells, in which uptake was followed via fluorescence
\nmicroscopy. The selectivity of the interaction was also investigated with mixed cell cultures.
\nOnly ligand-functionalized nanocontainers were able of specific and selective targeting of receptor
\nexpressing cells. Absence of ligand resulted in no uptake by cells expressing targeting receptors,
\nsupporting thus the stealth characteristics of the polymer brushc constituting the nanocontainer wall. Therefore, specific type of receptor targeting can be concluded for ligandfunctionalized
\nnanocontainers. Moreover, no cytotoxicity was observed for these artificial vesicles
\nin preliminary studies.
\nIn order to follow the pathway of the nanocontainers into the cells, gold nanoparticle
\nencapsulation was tested. Neither pre-formed nor in situ formation of gold nanoparticles rendered
\ngold encapsulation in polymer vesicles. Another approach was the use of a fluorescently
\nlabeled block-copolymer, for which the hydroxyl end groups of the triblock-copolymer were
\ncoupled covalently with a fluorescent molecule. However, for detection purposes encapsulation
\nof fluorescent dyes was sufficient and proved more flexible in terms of concentration range and
\nchoice of dye.
\nTo render surface-immobilized polymer vesicles, biotinylated polymers were used. Their
\nadsorption onto a streptavidin decorated surface was studied with a quartz crystal microbalance
\nwith dissipation (QCM-D). The results were not conclusive since an unexpected adsorption was
\nobserved for vesicles without biotin moieties. This adsorption could be ascribed to unspecific
\npolymer-protein interactions.
\nOther hydrophobic blocks with low Tg, such as poly(propylene oxide) and
\npoly(tetrahydrofuran) were investigated as replacements for poly(dimethylsiloxane) in poly(2-
\nmethyl-2-oxazoline)-b-poly(dimethylsiloxane)-b-poly(2-methyl-2-oxazoline) block-copolymers.
\nTheir surface activity was studied with Langmuir films, which rendered typical isotherms. Their
\naggregation was assessed by transmission electron microscopy (TEM) and dynamic light scattering
\n(DLS), mainly finding spherical aggregates that can be ascribed as vesicular structures.
\nFinally, these nanocontainers were studied as vehicles to entrap small solutes. By insertion
\nof membrane proteins, the permeability characteristics of the nanocontainers can be improved.
\nLangmuir film techniques showed protein-polymer interaction, which can be interpreted
\nas insertion in the polymer membrane. Insertion was further confirmed by entrapment of small
\nsolutes in the cavity of the nanocontainers by forming a complex with an already encapsulated
\ncounterion. This post-encapsulation approach results interesting as a recovery system, in which
\na substance could be easily removed from a complex matrix system, allowing the concentration
\nof the species of interest.

Removal of the neutral oil entrained in deep eutectic solvents using an anti-extraction method

Chemical modification of proteins by use of functional polymers is expected to endow them with new properties without destroying their native functions, thus providing useful materials for application in different fields. We have synthesized poly(N-isopropylacrylamide) [poly(IPAAm)] co-oligomer with N,N-dimethylacrylamide (DMAAm) and reactive end groups by telomerization of IPAAm. This co-oligomer exhibits a lower critical solution temperature (LCST) at 37 degrees C. Using this temperature-responsive semitelechelic co-oligomer, we prepared polymer-enzyme conjugates of lipase by covalent coupling via carboxyl end-groups. This bioconjugate exhibits a LCST at 37 degrees C, having rapid, reversible hydration-dehydration changes due to highly mobile free polymer end groups. The conjugate retained its native enzymatic activity below this critical temperature, above which it precipitated and its catalytic function was shut off. This conjugate can be readily separated from reaction mixtures as a precipitate by simple temperature changes after reaction and reused in cycles without denaturation. Such a modulated system is attractive for application as a novel bioreactor system.

Block copolymers of acryloxy propyl triethoxysilane and styrene were prepared through nitroxide‐mediated polymerization using alkoxyamine initiators based on N‐tert‐butyl‐1‐diethylphosphono‐2,2‐dimethylpropyl nitroxide. The copolymers were characterized by 1H NMR, size exclusion chromatography and differential scanning calorimetry. Their micellar behavior in dioxane/methanol solutions was examined through static light scattering and transmission electron microscopy (TEM). TEM indicated the successful formation of spherical micelles which were subsequently frozen by the sol–gel process. Hydrolysis–condensation of the reactive ethoxysilyl side groups was followed by FTIR, 1H NMR, and 29Si NMR. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 784–793, 2010

Peat soils are formed from woody materials which generally contain a lot of lignocellulosic organic compounds such as lignin which in the degradation process produces reactive carboxyl groups and phenolic compounds. Degradation of phenolic compounds can be carried out enzymatically by phenol- degrading bacteria. The purpose of this study was to compare the number of bacterial colonies degrading phenolic compounds in the acrotelic and catotelm layers in the upstream and downstream locations of the peat swamp forest in Permata Village, Terentang District, Kubu Raya Regency. Soil samples were taken in 2 plots (upstream and downstream from the canal blocking) at a distance of 500 meters using a peat drill. Each plot was then taken 3 drill points to form a triangular pattern with a distance of 30 meters with a peat depth level (Acrotelm) 0-10 cm, 10-20 cm and peat depth (Catotelm) 300-310 cm, 310-320 cm. Bacterial colonies were counted using the Total Plate Count method on Mineral Salt Medium and pure phenol selective media. Total phenolic compounds in peatlands were tested using 10% Folin-Ciocalteu solution and 2% Na2CO3. The number of bacterial colonies at locations upstream from the canal blocking in the acrotelmic layer is 0-10 cm deep (7,5x104 cfu/gr) and 10-20 cm deep (8,8x104 cfu/g), while bacteria in the catotelm layer are 300-310 cm deep (2,1x104 cfu/gr) and a depth of 310-320 cm (2,2x104 cfu/gr). The number of bacterial colonies downstream from the canal blocking in the acrotelm layer at a depth of 0-10 cm (2,3x104 cfu/gr) and at a depth of 10-20 cm (3,1x104 cfu/gr), while bacteria in the catotelm layer at a depth of 300-310 (1,7x104 cfu/g) and a depth of 310-320 cm (1,6x104 cfu/g).