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Cyclic polymers have very unique structure and properties, and thus have drawn intense research attention. However, controlled synthesis of cyclic polymers with predictable molar mass and narrow distribution is still a challenging task. In this study, we developed a novel cyclic catalyst that initiates the ring-expansion polymerisation of isocyanides, producing a series of cyclic helical polymers with predictable molecular weight and low dispersity. Interestingly, the ring-expansion polymerization of the isocyanide macromonomers gives well-defined cyclic bottlebrush polymers. The cyclic topology was demonstrated using transmission electron microscopy. [ABSTRACT FROM AUTHOR]

Cell-releasing hydrogel carriers enhance cell-based therapies by improving retention and viability within target tissues. We previously demonstrated tunable cell release from a hydrolytically labile β-thioester-containing polyethylene glycol-based hydrogel. However, the macromer synthesis dependent on thiol-Michael addition leads to batch variability and heterogeneous hydrogel properties. Herein, we report a new synthetic route with improved control of macromer molecular weight and characterize the resulting hydrogel properties. The resulting PEG dithioester acrylamide (PEGDTEA) hydrogel demonstrates a more controlled synthetic route to generate targeted molecular weights with reduced couplings, creating a more predictable and tunable hydrogel microenvironment for precise cell delivery applications. [ABSTRACT FROM AUTHOR]

The application of N‐heterocyclic carbene (NHC) catalysis under highly diluted oxidative condition to the polycondensation of dialdehydes and diols is herein presented as an alternative, atom‐economical synthetic route to macrocyclic oligoesters (MCOs). The disclosed protocol paves the way to the straightforward access to MCOs, starting from commercial dialdehydes, avoiding the use of toxic diacyl chlorides, commonly employed in traditional MCOs synthetic processes. The method is totally metal‐free, takes place in the green Me‐THF solvent and requires the use of a fully recyclable quinone oxidant. The protocol versatility is confirmed by the employment of fossil‐based and bio‐based monomers such as 2,5‐diformylfuran (DFF), 2,5‐bis(hydroxymethyl)furan (BHMF), and isomannide, synthesizing a series of novel and known synthetically relevant macrocyclic oligoesters, fully characterized by NMR and MALDI‐TOF MS analysis, with product yields (51–86 %) comparable to those obtained by traditional synthetic routes. Finally, to emphasize the synthetic relevance of the target macrocycles, an entropically‐driven ring opening polymerization (ED‐ROP) key study has been performed, optimizing the organocatalyzed synthesis of poly(2,5‐furan‐dimethylene 2,5 furandicarboxylate) (PBHMF) with number‐average molecular weight up to 8200 g mol−1 and 66 % isolated yield. [ABSTRACT FROM AUTHOR]

Pollution with organic dyes is one of the most typical environmental problems related to industrial wastewater. The removal of these dyes opens up new prospects for environmental remediation, but the design of sustainable and inexpensive systems for water purification is a fundamental challenge. This paper reports the synthesis of novel fortified hydrogels that can bind and remove organic dyes from aqueous solutions. These hydrophilic conetworks consist of chemically modified poly(ethylene glycol) (PEG-m) and multifunctional cellulose macromonomers ("cellu-mers"). Williamson etherification with 4-vinylbenzyl chloride (4-VBC) is used to modify PEGs of different molecular masses (1, 5, 6, and 10 kDa) and cellobiose, Sigmacell, or Technocell™ T-90 cellulose (products derived from natural renewable resources) with polymerizable/crosslinkable moieties. The networks are formed with good (75%) to excellent (96%) yields. They show good swelling and have good mechanical properties according to rheological tests. Scanning electron microscopy (SEM) reveals that cellulose fibers are visibly embedded into the inner hydrogel structure. The ability to bind and remove organic dyes, such as bromophenol blue (BPB), methylene blue (MB), and crystal violet (CV), from aqueous solutions hints at the potential of the new cellulosic hydrogels for environmental cleanup and clean water safeguarding. [ABSTRACT FROM AUTHOR]

PolyHIPEs are macroporous polymers templated within high internal phase emulsions (HIPEs). The ability to tailor the macromolecular and porous structures makes polyHIPEs of interest for three dimensional tissue engineering scaffolds. In this work, polyHIPEs with densities ranging from 0.18 to 0.28 g/cc were synthesized from novel biodegradable poly(ɛ-caprolactone) (PCL) macromers based on methacrylated oligomeric PCL diols of various molecular weights. Different types of internal phases generated porous structures that varied from networks of channels to highly interconnected voids. The crosslinked macromolecular structure limited PCL crystallization, resulting in elastomeric behavior with moduli of around 20 kPa. The HIPEs proved suitable for 3D printing both in air and in an innovative gel-bath. The suitability of the polyHIPEs for tissue engineering applications was indicated by their moduli, by their complete degradation within 4 h in 3 M NaOH, and by mesenchymal stem cells adhering and proliferating. The high level of viability can be attributed to the porosity that enables sufficient nutrient and waste diffusion. These results provide a foundation for designing 3D HIPE inks for printing macroporous tissue engineering scaffolds. [Display omitted] • Porous polycaprolactone (PCL): high internal phase emulsion (HIPE) templating. • Methacrylated PCL oligomers, various molecular weights (MWs): Elastomeric monoliths. • Porous structure affected by internal phase, crosslinked structure by MW. • 3D photo-printing: polymerize between layers in air, after printing in a gel-bath. • Mesenchymal stem cells adhered, proliferated. Porosity: nutrient, waste diffusion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Polymerization kinetics of linear and branched Poly(HEA) via RDRP in aqueous solution were investigated. • Linear and branched Poly(HEA) coatings were prepared by SI-RDRP to membrane surfaces. • Branched Poly(HEA) brush coating showed more excellent antifouling performance. Fabrication of hydrophilic coatings on membrane surface is one of the best methods to solve membrane fouling caused by oil or other pollutants. Recently, branched macromonomer as cross-linker in polymerization are proved to favor the uniformity and stability of coatings. Herein, we synthesized a branched macromonomer poly(ethylene glycol dimethacrylate) (BP(EGDMA)), which had abundant vinyl groups via catalytic chain transfer polymerization (CCTP), for fabrication of zwitterionic hydrophilic coatings with low volume shrinkage on different surface through photopolymerization. The low molecular weight cross-linkers with different functionality were used as control groups. The results of polymerization on glass plate showed that the hydrophilic coatings cross-linked by BP(EGDMA) was more uniform and stable. The surface chemistry, wettability and permeability of membranes were further investigated. The results showed that coatings which used macromonomer BP(EGDMA) as cross-linker on porous membrane surface was still more uniform than those which used low molecular weight cross-linkers. Meanwhile, the effects of the irradiation time and monomer usage on membrane coatings were explored to choose the best fabrication condition. Under the suitable conditions, the membrane used BP(EGDMA) as cross-linker showed a high oil rejection of >99 % among several oil-in-water emulsion. Moreover, the anti-biofouling experiment revealed that the macromonomer BP(EGDMA) would endow hydrophilic coatings with better fouling resistance by longer irradiation time and larger total monomer usage. [ABSTRACT FROM AUTHOR]

The paper presents the synthesis and characterization of star block copolymers based on polydimethylsiloxane and polycaprolactone. These copolymers were prepared by the ring opening polymerization of ε-caprolactone, using a single end type di-hydroxyalkyl terminated siloxane oligomer as macromonomer and stannous octoate as catalyst. Their chemical structures and molecular weights were characterized by 1H-NMR, FTIR and SEC, and thermal properties were determined by DSC. DSC analyses were also conducted to estimate the crystallinity degree of the PCL and PDMS blocks. [ABSTRACT FROM AUTHOR]

The focus of this paper is to report the quantitative synthesis of bis‐epoxy end functionalized polyisoprene (BETPI) macromonomers by anionic polymerization and reversible addition fragmentation chain transfer (RAFT) polymerization. For anionic polymerization, more stable and sterically hindered living anions polyisoprene (Li+‐PIp‐Li+) react with epichlorohydrin (ECH) for the synthesis of well‐defined BETPI. For the high‐pressure RAFT polymerization, a novel bis‐epoxy end functionalized trithiocarbonate (BODAAT) is designed as RAFT agent for the polymerization of isoprene monomer to obtain well‐defined BETPI. The functionalities of the resulting BETPI are analyzed by Fourier transform infrared spectroscopy (FT‐IR), NMR, and size exclusion chromatography (SEC). Through two polymerization methods, the BETPI with 600–1000 Da of molecular weight and over 75% of epoxy end capping rate is obtained, which can be further utilized as highly reactive liquid macromonomers. [ABSTRACT FROM AUTHOR]

The synthesis and solution properties of thermoresponsive polymer molecular brushes based on five novel diblock macromonomers (methoxy [oligo(ethylene glycol)e-block-oligo(propylene glycol)p] methacrylates, OEGeOPGpMA, where e = 7.0–10.3 and p = 2.8–10.3) have been studied. The effect of synthesis conditions on the rate of radical solution polymerization in ethyl acetate, maximum conversions of macromonomers, and molecular weight characteristics of polymers has been shown. Homopolymers of OEGeOPGpMA exhibited pronounced surface-active properties. The influence of the length of oligo(propylene glycol) block on the degree of reduction of surface (air–water) and interfacial (hexane-water) tension was shown. The aggregation behavior of polymers was investigated by dynamic light scattering and fluorimetry using pyrene as a fluorescent probe. The dependence of critical micelle concentration on the length of the oligo(propylene glycol) block was shown. The polymers have a critical solution temperature within the range of 34–71 °C depending on the length of oligo(oxyalkylene) blocks and polymer concentration. The relationship between the distribution coefficient of macromonomers in water–oil systems and the LCST of polymers based on them has been established. [ABSTRACT FROM AUTHOR]

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article presents a fast, straightforward synthesis approach to polymerize alternating multiblock copolymers, ultra‐high molecular weight (UHMW) (homo)polymers as well as precursors for complex macromolecular topologies such as comb or barbwire architectures. The one‐pot synthesis strategy proposed in this work is based on anionic polymerization via a bifunctional initiator and the subsequent linking of macro dianions with a bifunctional linker, additionally overcoming the limitations associated with the monomer reactivity. Thus, the synthetic route guarantees the repeating size of polymer blocks and an equal distribution of functional groups in precursors for complex topologies. Dianions of polystyrene (PS), polyisoprene‐b‐polystyrene‐b‐polyisoprene, and poly‐2‐vinylpyridine‐b‐polystyrene‐b‐poly‐2‐vinylpyridine are linked with α,α′‐dibromo‐para‐xylene to UHMW and multiblock copolymers. Multiblock copolymers with on average up to 50 well‐defined alternating A and B blocks are accessible within 15 min. [ABSTRACT FROM AUTHOR]

Copyright of Revista de la Sociedad Química del Perú is the property of Sociedad Quimica del Peru and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Three azido-terminated poly(ethylene glycol) macromonomers (ATPEGs) were synthesized from poly(ethylene glycol)s (PEGs) and characterized. The extended polytriazole (EPTA) resins were prepared from the macromonomers, azide and alkyne monomers. Toughening effect of PEGs on polytriazole resins was analyzed by means of mechanical, thermal and electronic microscope characterization. The results show that molecular weight and content of ATPEGs have great influence on the thermal and mechanical properties of cured EPTA resins. The impact strength of cured EPTA resins increases with the increase of the amount and molecular weight of ATPEGs. The flexural strength and heat resistance of cured EPTA resins decrease with the increase of addition amount and molecular weight of ATPEGs. High impact EPTA resins were obtained. [ABSTRACT FROM AUTHOR]

Poly[Ɛ-CL-b-(MMA-comb-EMA)]comb-type polymers were synthesized by ATRP and Ɛ-caprolactone macroinitiator and macromonomer. Methyl methacrylate macromonomer was synthesized from acylation reaction of methacryloyl chloride with PMMA ended 7-hydroxy coumarin. The macroinitiator was prepared from the reaction of chlorine acetyl chloride P(Ɛ-CL). The synthesized polymers were characterized by FT-IR, 1H-NMR and 13C-NMR techniques. The average molecular weight and molecular weight distribution of polymers were measured by GPC method. Thermal properties of samples were studied by DSC/TGA techniques. Dielectric and Ac conductivity measurements were performed. Dielectric constant (ɛˈ), dielectric loss factor (ɛˈˈ) and conductivity behaviors of comb-type polymer were measured at room temperature between the frequency of 100–2000 Hz and over the temperature range 303–413 K at 1 kHz reported as compared with each other. Besides, their effects on the electrical properties by doping with EuCl3 for some of the comb copolymers were and were investigated. The activation energy (Ea) was calculated from conductivity. We reported it was determined that the (ɛˈ) and (ɛˈˈ) values decreased with increasing frequency. There are also many application areas for comb polymers for example; nanotechnology, medicine. The aim of this study is to synthesize comb-type copolymers in different compositions and to investigate their electrical properties. [ABSTRACT FROM AUTHOR]

The development of genipin modification methods has attracted much attention to improve the functional properties of proteins in the fields of food science. In this work, two types of pH-responsive genipin-crosslinked bovine bone gelatin conjugates with high surface hydrophobicity were developed for emulsion stabilization. One was genipin molecule-crosslinked gelatin conjugates prepared at acidic pH and the other was genipin macromer-crosslinked gelatin conjugates prepared at neutral and basic pH. The degrees of crosslinking increased with the increase of preparation pH. They increased with the increase of genipin-to-gelatin mass ratios at acidic pH, whereas decreased with the increase of genipin-to-gelatin mass ratios at neutral and basic pH. The surface hydrophobicity values, molecular weights, and emulsifying properties (creaming stability, emulsion activity index, and emulsion stability index) of the obtained conjugates increased with the increase of both preparation pH and genipin-to-gelatin mass ratios. This work provided useful knowledge to understand how the preparation parameters (preparation pH and genipin-to-gelatin mass ratio) and genipin structures (molecule and macromer) affect a protein's degrees of crosslinking, physicochemical properties, and emulsifying properties. [Display omitted] • Two types of genipin-crosslinked gelatin conjugates were obtained at different pH. • Effect of genipin-to-gelatin ratio on the degrees of crosslinking depended on the pH. • 1-to-1 and n-to-1 crosslinking occurred at acidic pH. • 1-to-1, n-to-1, and macromer-to-1 crosslinking occurred at neutral and basic pH. • Conjugates prepared with pH 9.0 or 1:50 (ratio) induced the best emulsion stability. [ABSTRACT FROM AUTHOR]

Cationic bottlebrush homopolymers are polymerized using a grafting‐through approach by ring‐opening metathesis polymerization (ROMP) to afford well‐defined polymers. Quaternary ammonium macromonomers (MMs) are prepared by quaternizing tertiary amine MMs synthesized by reversible addition‐fragmentation chain transfer (RAFT) polymerization. The quaternary ammonium MMs undergo ROMP to target molecular weights (Mn = 30 000–100 000 g mol−1) and a low dispersity (Đ = 1.10–1.30). Halide‐ligand exchange between the third generation Grubbs catalyst (G3) and halide counter ions (bromide and iodide ions) of MMs changes the catalyst activity throughout ROMP, causing it to deviate from pseudo‐first order kinetic behavior; however, the polymerization still follows controlled behavior without significant catalyst termination. Increasing steric bulk of the MMs decreases the polymerization rate as well. Amphiphilic block copolymers are synthesized by sequential polymerization of quaternary ammonium MMs and polystyrene (PS) MMs. Using a PS macroinitiator affords block copolymers with lower Đ values as compared to the less active cationic macroinitiator. [ABSTRACT FROM AUTHOR]

• A novel octene-terminated PDMS macromonomer is synthesized with good yield. • The first study on the efficient preparation of PE-g-PDMS by direct copolymerization. • The effect of PDMS content on copolymer microstructure is studied. • Small addition of PE-g-PDMS into HDPE can improve the melting flow property. This paper discusses the synthesis of polyethylene-g-polydimethylsiloxane (PE-g-PDMS) graft copolymers through a facile macromonomer approach. A novel octene-terminated PDMS macromonomer was synthesized via anionic ring-opening polymerization of hexamethylcyclortrisiloxane and the subsequent chain-end capping with dimethyl(oct-7-enyl)chlorosilane. A systematic investigation was conducted on the VCl 3 (THF) 3 /Et 2 AlCl-catalyzed copolymerizations of the PDMS macromonomer with ethylene by varying the macromonomer feed. The relatively high activity of 11.6 kg/(mmol V ·h) was observed even at a rather high macromonomer feed of 160 mmol/L, which is first reported and of great significance in the efficient fabrication of polyethylene-g-polysiloxane graft copolymers. The resulting PE-g-PDMS copolymers were characterized to determine the chain structure, molecular weight and molecular weight distribution. The highest macromonomer incorporation (3.77 mol%) was achieved at the highest macromonomer feed with a decreased molecular weight and a narrower molecular weight distribution. DSC analysis revealed that melting temperature and crystallinity of PE-g-PDMS copolymers systematically decreased with increasing of the PDMS macromonomer incorporation. When quite a small amount (2 wt%) of PE-g-PDMS copolymers was added to HDPE via melt blending, the melt flow rate of HDPE increased by 32% and the mechanical properties remained almost unchanged. [ABSTRACT FROM AUTHOR]

Well-controlled polystyrene-polymethacrylate bottlebrush block copolymers (BBCPs) of ultrahigh molecular weight using ω -end-norbornyl polystyrene as the macromonomer for the first block were synthesized by combining living anionic polymerization (LAP) and ring-opening metathesis polymerization (ROMP). The ω -end-norbornyl polystyrene (NB-PSt), poly(tert -butyl methacrylate) (NB-P t BMA), poly(methyl methacrylate) (NB-PMMA), and poly(benzyl methacrylate) (NB-PBzMA) macromonomers (MMs) were synthesized by the LAP. The ROMP of the MMs led to poly(NB- g -St) (molecular weight, M n = 1515 kDa, and dispersity, Ð = 1.12), poly(NB- g - t BMA) (M n = 1470 kDa, Ð = 1.49), poly(NB- g -MMA) (M n = 1128 kDa, Ð = 1.42), and poly(NB- g -BzMA) (M n = 941 kDa, Ð = 1.16) bottlebrush homopolymers at degree of polymerization (DP) of 500. Synthesis of the BBCP, P(NB- g -St)- b -P(NB- g - t BMA) was well-controlled with high molecular weight and a low dispersity (M n = 3002 kDa, Ð = 1.17) with a total DP of 976. The self-assembly of the resulting BBCP films revealed periodic lamellar morphologies with characteristic photonic crystal properties. Image 1 • Ultrahigh molecular weight BBCPs based on polystyrene and polymethylacrylates are synthesized for the first time. • The ROMP for NB-PSt as the first block led to facile and well-controlled ROMP of norbornyl-functionalized polymethacrylates. • The resulting BBCPs showed the characteristic photonic crystal properties except those of PSt and PBzMA. [ABSTRACT FROM AUTHOR]

Thermo-responsive micelles were prepared from brush-like block copolymers of proline-derived norbornene and macromonomers bearing oligo(lactide) groups. The brush-like polymers with moderate molecular weights were synthesized by the ring-opening metathesis block copolymerization of a proline-functionalized norbornene (1) with norbornene macromonomers bearing oligo(lactide) groups using Umicore M31 as a catalyst. The proline-functionalized polynorbornene [poly(1)] exhibited the lower critical solution temperature (LCST) at 18 °C. Phase separation was reversible on heating and cooling without hysteresis. Poly(1) featured amphiphilic character, it self-assembled to form micelles in water at temperatures below the LCST, and aggregation of micelles was observed above the LCST. The LCST of the block copolymers increased with increasing percentage of the branched oligo(lactide) component, suggesting that the phase transition temperatures are tunable with respect to the monomer composition. The block copolymers self-assembled into micelles below the LCST, and further aggregated into larger particles, presumably due to dehydration at the corona, at temperatures above the LCST. The block copolymers also showed the potential to self-assemble into a variety of shapes determined by the amphiphilic balance of the block components. Image 1 • Thermo-responsive brush-like block copolymers were synthesized by ROMP. • The polymers self-assembled in cold water and further aggregated at temperatures above the LCST. • The LCST and shape of the aggregates were tunable by amphiphilic balance of the block copolymers. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Isoprene‐terminated polybutadiene macromonomers synthesized in high yield. • Well‐behaved anionic copolymerization accomplished with 1,4‐butadiene. • High cis ‐1,4‐microstructure content maintained in the backbone and the side chains. Abstract Polybutadiene macromonomers with a high 1,4-microstructure content and a polymerizable isoprene end group were synthesized by termination of living polybutadienyllithium chains. While different isoprene derivatives were investigated as terminating agents for the preparation of the macromonomers, 2-bromomethyl-1,3-butadiene provided the best results. The termination reaction was optimized in terms of solvent composition, reaction temperature and reactivity-modifying additives used. The addition of 10 eq of terminating agent in equal volumes of hexane and tetrahydrofuran at −110 °C provided the macromonomer in 95% yield. Anionic copolymerization of the macromonomer with 1,3-butadiene in hexane yielded branched polybutadiene with a narrow molecular weight distribution (M w /M n = 1.07), but seeded initiation was necessary to avoid side reactions leading to multimodal molecular weight distributions. [ABSTRACT FROM AUTHOR]

Bottlebrush polymers (BBPs) are three‐dimensional polymers with great academic and industrial potential owing to their highly tunable and intricate architecture. The most popular method to synthesize BBPs is ring‐opening metathesis polymerization (ROMP) with Grubbs' catalyst, allowing living grafting‐through polymerization of macromonomers of up to ultrahigh molecular weights with narrow molecular weight distribution. In this case, it has been well recognized that the purity of macromonomers (MMs) is critical for a successful ROMP reaction. For MMs synthesized from reversible‐deactivation radical polymerization, Grubbs and Xia demonstrated that the better control of ROMP reaction can be achieved when they are prepared via "growth‐then‐coupling" method that is coupling a norbornenyl group to end‐functionalized prepolymers. However, these MMs can also contain various residual impurities from previous synthetic steps, which can potentially poison the catalyst and hamper the ROMP reaction. Herein, we intentionally doped possible impurities into purified MMs to identify the most poisoning species. As a result, it was found that alkyne‐functionalized norbornene most significantly retarded the ROMP reaction due to a formation of Ru‐vinyl‐carbene intermediates having low catalytic reactivity, whereas the other reagents such as solvent, Cu‐catalyst, ligands, and azido‐terminated prepolymers were relatively inert. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 726–737 Ring‐opening metathesis polymerization (ROMP) is the most popular approach to synthesize the well‐defined bottlebrush polymers, but the purity of macromonomer (MM) is important for successful ROMP. Herein, we systematically examined the effect of impurities on the ROMP for MMs that were prepared via growth‐then‐coupling method based on the Cu(I)‐catalyzed azide‐alkyne cycloaddition click reaction. It was found that alkyne‐functionalized norbornene most significantly retarded the ROMP reaction, whereas the other reagents were relatively inert. [ABSTRACT FROM AUTHOR]

Phase-separated networks made from different macromonomers with disparate properties provide a platform where the molecular weight between cross-links (Mc) can be varied leading to tunable mechanical and conductive properties. To form networks with bimodal Mc's, two volume fraction series, A and B, were synthesized from telechelic polystyrene (PS) and poly(ethylene oxide) (PEO) of varying molecular weights (MW), using thiol-norbornene chemistry to tune Mc. Series A consisted of 4K PEO and 12K PS, and series B consisted of 12K PEO and 5K PS. Phase separation in the network was confirmed by DSC where two distinct glass transition temperatures were observed and by SAXS where broad, weakly ordered scattering was observed. The networks were further characterized to probe how bimodal Mc affects the mechanical and conductive properties of phase-separated networks. The two series demonstrated that the asymmetric MW studied herein had little effect on mechanical and lithium conductive properties while changes in these properties were primarily influenced by the volume fraction of PEO. [ABSTRACT FROM AUTHOR]

Branched polymers are a valuable class of polymeric materials. In the present study, anionic polymerization techniques were employed for the synthesis of low molecular weight poly(ethylene oxide) (PEO) macromonomers bearing norbornenyl end groups. The macromonomers were characterized by SEC, MALDI-TOF and NMR spectroscopy. Subsequent ring opening metathesis polymerization (ROMP) of the macromonomers using ruthenium catalysts (Grubbs catalysts of the 1st, 2nd and 3rd generations) afforded the corresponding polymacromonomers. The effects of the macromonomer molecular weight, the type of the catalyst, the nature of the solvent, the monomer concentration and the polymerization temperature on the molecular characteristics of the branched polymers were examined in detail. The crystallization behavior of the macromonomers and the corresponding polymacromonomers were studied by Differential Scanning Calorimetry (DSC). The thermal stability and the kinetics of the thermal decomposition of the samples were also studied by Thermogravimetric Analysis (TGA). The activation energies of the thermal decomposition were analyzed using the Ozawa-Flynn-Wall and Kissinger methodologies. [ABSTRACT FROM AUTHOR]

Two solution reactors in series are utilized to synthesize poly(ethylene-cb-propylene) comb block copolymers, P(E-cb-P), where the first reactor prepares vinyl terminated atactic polypropylene (aPP) macromers from propylene using an organometallic catalyst favoring beta methyl elimination and the second reactor copolymerizes aPP macromers with ethylene using a different organometallic catalyst capable of incorporating macromers. The products are P(E-cb-P) comb block polymers with bimodalities in molecular weight, composition, and long chain branching. Low molecular weight (MW) components are linear and of mixed compositions consisting of random copolymers of ethylene and propylene and residual vinyl terminated aPP macromers. High MW components are comb branched with constant composition, and block copolymers. Even though the PE backbone is immiscible with the aPP comb arms, the presence of linear low MW ethylene-propylene random copolymer prevents the high MW comb block components from self-association into segregated domains or micelles when it is blended into high density polyethylene (HDPE) or isotactic polypropylene (iPP). By hindering micelle formation, this bimodal P(E-cb-P) can be intimately entangled with HDPE and with iPP delivering extensional flow hardening when it was added at 5%. Extensional strain hardening is observed at 5% addition of the bimodal P(E-cb-P) comb block copolymer in 50/50 HDPE/iPP blends with exceptionally high strain hardening ratio. It was found that this bimodal P(E-cb-P) comb block copolymer can compatibilize immiscible blends of HDPE and iPP resulting in domain size reductions and diffused interfaces. The enhanced strain hardening observed in blends with the bimodal P(E-cb-P) comb block addition may arise from the increases in the blend interfacial area and the entanglement of the blocks within the homopolymer phases. [ABSTRACT FROM AUTHOR]

Control over bottlebrush polymer synthesis by ring-opening metathesis polymerization (ROMP) of macromonomers (MMs) is highly dependent on the competition between the kinetics of the polymerization and the lifetime of the catalyst. We evaluated the effect of anchor group chemistry--the configuration of atoms linking the polymer to a polymerizable norbornene--on the kinetics of ROMP of polystyrene and poly(lactic acid) MMs initiated by (H2IMes)(pyr)2(Cl)2Ru=CHPh (Grubbs third generation catalyst). We observed a variance in the rate of propagation of >4-fold between similar MMs with different anchor groups. This phenomenon was conserved across all MMs tested, regardless of solvent, molecular weight (MW), or repeat unit identity. The observed >4-fold difference in propagation rate had a dramatic effect on the maximum obtainable backbone degree of polymerization, with slower propagating MMs reducing the maximum bottlebrush MW by an order of magnitude (from ~106 to ~105 Da). A chelation mechanism was initially proposed to explain the observed anchor group effect, but experimental and computational studies indicated that the rate differences likely resulted from a combination of varying steric demands and electronic structure among the different anchor groups. The addition of trifluoroacetic acid to the ROMP reaction substantially increased the propagation rate for all anchor groups tested, likely due to scavenging of the pyridine ligands. Based on these data, rational selection of the anchor group is critical to achieve high MM conversion and to prepare pure, high MW bottlebrush polymers by ROMP grafting-through. [ABSTRACT FROM AUTHOR]

Bottlebrush polymers are synthesized using a tandem ring-opening polymerization (ROP) and ring-opening metathesis polymerization (ROMP) strategy. For the first time, ROP and ROMP are conducted sequentially in the same pot to yield well-defined bottlebrush polymers with molecular weights in excess of 106 Da. The first step of this process involves the synthesis of a polylactide macromonomer (MM) via ROP of d, l-lactide initiated by an alcohol-functionalized norbornene. ROMP grafting-through is then carried out in the same pot to produce the bottlebrush polymer. The applicability of this methodology is evaluated for different MM molecular weights and bottlebrush backbone degrees of polymerization. Size-exclusion chromatographic and 1H NMR spectroscopic analyses confirm excellent control over both polymerization steps. In addition, bottlebrush polymers are imaged using atomic force microscopy and stain-free transmission electron microscopy on graphene oxide. [ABSTRACT FROM AUTHOR]

Various macromonomers (MMs) were synthesized using controlled radical polymerization (CRP) by either directly growing from a norbornene-functionalized initiator or chain transfer agent ("direct-growth" or DG method) or coupling a norbornenyl group to preformed polymers ("growth-then-coupling" or GC method). The degree of control for the ring-opening metathesis polymerization (ROMP) of these MMs was found to be dependent on which synthetic method was used for the MMs. Narrowly dispersed brush polymers were consistently obtained from the GC-MMs. In contrast, the DG-MMs resulted in brush polymers with a small high-molecular weight (MW) shoulder or broader molecular weight distribution (MWD). Matrix-assisted laser desorption ionization time-of-flight mass spectrometry of DG-MMs showed the presence of a small amount of α,ω-dinorbornenyl telechelic species resulting from the biradical combination during polymerization. A control study further revealed that even the presence of 1 mol % α,ω-norbornenyl telechelic polymer in the MM resulted in broadening of MWD. Our surprising findings suggest the importance of MM quality and the absence of dinorbornenyl telechelic polymers in achieving the best control for high-MW brush polymers via efficient ROMP of MMs. [ABSTRACT FROM AUTHOR]

A hot-meltpressure-sensitive adhesive (PSA) was generated containinga high content of renewable biomass. The polymer is based on a commercialhot-melt acrylic formulation containing primarily 2-ethylhexyl acrylate(EHA). The new polymer is synthesized with a majority of the EHA replacedwith a macromonomer (MM) prepared with l-lactide and ε-caprolactonevia catalyzed bulk ring-opening polymerization using N-hydroxyethyl acrylamide as the initiator. Incorporation of the MMinto the polymers was confirmed via proton NMR. The properties andadhesive performance of the new polymer were compared with those ofits 100% acrylic commercial version. When synthesized using the sameapproach, the biomass-containing PSA had a lower molecular weight,higher glass transition temperature, and lower melt viscosity. Introductionof MM had little impact on the tack force, shear time, and shear adhesionfailure temperature, and the peel strength increased substantially.It is expected that these hybrid materials can be optimized for avariety of self-adhesive applications. [ABSTRACT FROM AUTHOR]

This paper describes the synthesis of the 2- and 4-functional acrylic exo-7-oxanorbornene species 2-((2-((3a R,7a S)-1,3-dioxo-1,3,3a,4,7,7a-hexahydro-2 H-4,7-epoxyisoindol-2-yl)ethoxy) carbonyl)-2-methylpropane-1,3-diyl diacrylate and (((2-((2-((3a R,7a S)-1,3-dioxo-1,3,3a,4,7,7a-hexahydro-2 H-4,7-epoxyisoindol-2-yl)ethoxy) carbonyl)-2-methylpropane-1,3-diyl)bis(oxy))bis(carbonyl))bis(2-methylpropane-2,1,3-triyl) tetraacrylate, and their use as common precursors for the preparation of a small library of dendronized thioether adducts via nucleophile-mediated thiol- Michael coupling chemistry. We subsequently demonstrate that the dendronized monomers can be (co)polymerized via ring-opening metathesis polymerization employing Grubbs'-type Ru-based initiators to give novel functional dendronized (co)polymers of predictable molecular weights and acceptable dispersities ( ĐM = [ABSTRACT FROM AUTHOR]

Thestructure and crystallization properties of a norbornene end-functionalizedsyndiotactic polypropylene (sPP) macromonomer (MMsPP) with [rrrr] = 80 mol % and molecular mass Mn= 3600 g/mol and corresponding comb-like poly(macromonomer)(pMMsPP) with Mn= 100000 g/mol have beeninvestigated using wide angle (WAXS) and small angle (SAXS) X-rayscattering, atomic force (AFM), transmission electron (TEM), and optical(OM) microscopy. The analysis reveals the tendency of the macromonomerand poly(macromonomer) to form structures characterized by layersof sPP chains alternated to layers occupied by the cyclic groups (norborneneor polynorbornene), and a small degree of interdigitation of sPP chainsbelonging to adjacent layers facing each other in an end-to-end arrangement.It is argued that this layering is dictated, upon crystallization,by nanophase separation of the flexible sPP chains in regions apartfrom those occupied by the cyclic groups coupled to formation of sPPcrystals organized in the lamellar morphology. SAXS measurements indicatethat in isothermally crystallized samples the layered structures areirregular and include sPP lamellar crystals of uniform thickness separatedby amorphous layers whose thickness values have a multimodal distribution.These properties are intrinsic to the chemical structure of our systemsand are only minimally influenced by the topological constrains ofthe covalent bonding of macromonomers in the corresponding comb-polymer. [ABSTRACT FROM AUTHOR]

Dendronized polymers were synthesizedfrom various endo-tricycle[4.2.2.0]deca-3,9-diene(TD) monomers, using a macromonomerapproach, via ring-opening metathesis polymerization. The polymerizationwas achieved in a living manner to give dendronized polymers withhigh molecular-weights and narrow polydispersity index. The resultingpolymers showed highly extended conformations both in solution andin the solid state, even with relatively small third-generation esterdendrons, because of the rigid backbone of TD monomers. Using theirrigidity, block and gradient copolymers containing TD and norbornenemoieties were synthesized. Diblock copolymers were produced by thesequential addition of two dendronized macromonomers, and gradientcopolymers were produced in a simple batch reaction, because largedifferences in reactivity allowed for the simultaneous one-pot polymerization,favoring TD over norbornene. Polymer conformations were confirmedby both scattering analysis in solution and atomic force microscopy(AFM) imaging in thin films. The high-resolution AFM images of bothcopolymers enabled us to distinguish the structural differences betweenthe two classes of copolymers because the block copolymer showed clearboundary for each block while the gradient copolymer showed gradualchanges in height and thickness. Furthermore, a comparison of therigidities of these two copolymers was performed by scattering analysisin solution. [ABSTRACT FROM AUTHOR]

series of novel cross-linked poly (urethane-methacrylate)s (PUAs) were synthesized in a three-step process: Four kinds of low number average molecular weight aromatic polyesters (PEs) with terminal hydroxyl groups were obtained by phthalic anhydride (PA) reacted with 1,2-propanediol (PDO), 1,4-butanediol (BDO), 1,6-hexanediol (HDO), and diethylene glycol (DEG), respectively. Then, a series of urethane-methacrylate macromonomers(UMAs), which have double bonds at the end of the chain, were prepared from isophorone diisocyanate (IPDI), the PEs obtained in first step, poly(ethylene glycol) 600 (PEG600) and ß-hydroxyethyl methacrylate(HEMA). Dibutytin dilaurate (DBTL) was used as catalyst. Finally, a series of thermosetting PUAs were synthesized by the polymerization of novel functional UMAs using 2,2'-azobis(isobutyronitrile) (AIBN) as catalyst. The compositions of the PEs and UMAs were determined by H-NMR and fourier transform infrared (FT-IR). The properties of PUAs were measured by dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), wide-angle X-ray diffraction (WAXD), water uptake and optical properties testing, and mechanical performance measurements. The results revealed that the mechanical and degradation properties of PUAs were influenced by the kinds of PE or polyether polyols in the PUAs remarkably. The obtained PUAs present the good thermal and mechanical properties, low water uptake (below 1%) and high transparence (above 90%). The diversity of properties suggests that these PUAs can be used in a wide range of excellent optical polymer applications. [ABSTRACT FROM AUTHOR]

A combination of iridium‐catalyzed CH activation/borylation and atom transfer radical polymerization (ATRP) was used to generate polar graft copolymers of syndiotactic polystyrene (sPS). The borylation at aromatic CH bonds of sPS and subsequent oxidation of boronate ester proceeded without negatively affecting the molecular weight properties and the tacticity of sPS. A macroinitiator suitable for ATRP could be synthesized by the esterification of 2‐bromo‐2‐methylpropionyl bromide and hydroxy‐functionalized sPS. The graft polymerizations of methyl methacrylate and tert‐butyl acrylate from the macroinitiator using ATRP afforded polar block grafted sPS materials, syndiotactic polystyrene‐graft‐poly(methyl methacrylate) (sPS‐g‐PMMA) and syndiotactic polystyrene‐graft‐poly(tert‐butyl acrylate) (sPS‐g‐PtBA). The latter was hydrolyzed to yield an amphiphilic graft copolymer, syndiotactic polystyrene‐graft‐poly(acrylic acid) (sPS‐g‐PAA). The structures of the copolymers were characterized by NMR and FTIR spectroscopies. Size exclusion chromatography and 1H NMR spectroscopy were used to study any changes in the molecular weight properties from the parent polymer. A decrease in the hydrophobicity of the graft copolymers was confirmed by water contact angle measurements. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6655–6667, 2009 [ABSTRACT FROM AUTHOR]

[Display omitted] • Microreactor-based chemo-enzymatic ROP-ROMP cascade reaction platform. • Continuous flow synthesis of PNB- g -PCL bottlebrush polymers. • High efficiency, macromonomer isolation free, and well-defined structure. Microreactor-based enzymatic ring-opening polymerization (ROP) and metal-catalytic ring-opening metathesis polymerization (ROMP) cascade reaction platform was developed for graft through synthesis of bottlebrush polymers. Single and integrated microreactor system were assembled for the evaluation of ROP, ROMP, and ROP-ROMP, respectively. By applying a continuous flow chemo-enzymatic ROP-ROMP strategy, a series of well-defined poly(norbornene)- graft -poly(ε-caprolactone) (PNB- g -PCL) bottlebrush polymers were successfully prepared with fast kinetics, exemption of macromonomer isolation and purification, the absence of macromonomer residue in the product, controlled molecular weight and narrow distribution. This work would provide inspiration for the chemo-enzymatic synthesis, microflow chemistry, and bottlebrush polymers. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fatty acid derived ester-urethane telechelic macromonomers were synthesized with Bi and Zn catalysts. • Syntheses were performed in ethyl acetate (a green solvent) • Reaction kinetics of non-toxic Bi and Zn catalysts were compared to organotin catalyst. • Elastomeric films were created in air and argon by photopolymerization. • The use of non-toxic solvent and catalysts increased cell viability in vitro. Photocurable materials that can be delivered as liquids and rapidly (within seconds) cured in situ using UV light are gaining increased interest in advanced minimally invasive procedures. The aim of this work was to synthesize and characterize fatty-acid-derived ester-urethane telechelic (methacrylate) macromonomers, suitable for photopolymerization. The commonly used dibutyltin dilaurate catalyst was replaced with bismuth neodecanoate, bismuth tris(2-ethylhexanoate), and zinc (II) acetyloacetonate as less-toxic alternative catalysts. Additionally, ethyl acetate was used as a "green" solvent. The progress of the two-step synthesis was monitored with infrared spectroscopy. The chemical structure and molecular weight of the obtained viscous materials was characterized with nuclear magnetic resonance spectroscopy and gel permeation chromatography. Photocrosslinking of the macromonomers into elastomeric films was achieved using 150 s per spot of UV light (20 mW/cm2) exposure. Mechanical tensile testing of the films indicated their elasticity up to 120% and low modulus typical for soft and elastomeric materials. Finally, in vitro cytotoxicity tests showed high cell viability for the case of materials synthesized using bismuth and zinc catalysts. Overall, our results indicate that bismuth and zinc catalysts are excellent alternatives to organotin compounds in the synthesis of photocurable methacrylate ester-urethanes with improved environmental and safety profile, and for potential biomedical applications. [ABSTRACT FROM AUTHOR]

Amphiphilic copolymers are appealing materials because of their interesting architecture and tunable properties. In view of their application in the biomedical field, the preparation of these materials should avoid the use of toxic compounds as catalysts. Therefore, enzymatic catalysis is a suitable alternative to common synthetic routes. Pentablock copolymers (CUC) were synthesized with high yields by ring-opening polymerization of ε-caprolactone (ε-CL) initiated by Pluronic (EPE) and catalyzed by Candida antarctica lipase B enzyme. The variables to study the structure–property relationship were EPEs' molecular weight and molar ratios between ε-CL monomer and EPE macro-initiator (M/In). The obtained copolymers were chemically characterized, the molecular weight determined, and morphologies evaluated. The results suggest an interaction between the reaction time and M/In variables. There was a correlation between the differential scanning calorimetry data with those of X-ray diffraction (WAXD). The length of the central block of CUC copolymers may have an important role in the crystal formation. WAXD analyses indicated that a micro-phase separation takes place in all the prepared copolymers. Preliminary cytotoxicity experiments on the extracts of the polymer confirmed that these materials are nontoxic. [ABSTRACT FROM AUTHOR]

• Synthesis of three-armed macromers with a range of biodegradable building blocks and degrees of end group methacrylation. • Macromers contain oligolactide building blocks with adjustable glycolide incorporation. • Fabricated macromer-based macroporous scaffolds show degradation with continuous mass loss and only mild pH decrease. • Degradation rate dependent on macromer hydrophilicity (core, glycolic acid content), molecular weight and composition. Acidification of implant microenvironment and inflammation due to degradation products of high molecular weight poly(α‑hydroxy acids) like PLA and PLGA is a risk that can limit their use in regenerative medicine, tissue engineering and drug delivery. We developed macromers that consist of a three-armed core with varying degrees of ethoxylation, hydrolytically degradable oligolactide blocks and terminal methacrylate groups (TriLA macromers) for cross-polymerization into monolithic or macroporous structures. Within the macromer platform, biophysical and biochemical properties can be adjusted by macromer chemistry. In this work, eight new macromer types with a reduced degree of methacrylation or substitution of a fraction of the lactic acid units with glycolic acid were successfully synthesized starting from a fully methacrylated, oligolactide-based TriLA macromer. Chemical characterization confirmed feed-dependent glycolic acid integration and controlled reduction in degree of methacrylation. The degradation behavior of macroporous scaffolds made by solid lipid templating from both the previously established and the new macromers was systematically investigated. In general, the scaffolds displayed continuous mass loss over time when the onset time of degradation was passed. Depending on arm length as well as hydrophilicity of the oligomeric building blocks, degradation half-life ranged from 3 to 4 weeks to over 81 weeks. Glycolic acid integration accelerated network degradation more effectively than an increase in core molecule hydrophilicity. The observed, adjustable degradation profiles with only moderate medium acidification and a dominant phase of almost linear mass loss make this material platform promising for regenerative and drug delivery applications. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Biodegradable isocyanate-containing polymers were synthesized via Cu(0)-mediated controlled radical polymerization. • Good stability and well-defined morphology of powder-form biodegradable liquid-core microcapsules were obtained. • The effect of fabrication conditions on microcapsule properties was investigated. A combination of reversible deactivation radical polymerization (RDRP), isocyanate chemistry, and a convenient drying process via spray drying is employed to fabricate powder-form biodegradable liquid-core microcapsules. Two different molecular weight α,ω-poly(ε caprolactone) RDRP macroinitiators were first prepared through esterification to obtain the degradable α-halo ester initiators. Subsequently, poly(benzyl methacrylate- co -isocyanatoethyl methacrylate) (P(BnMA a - co -IEM b)) copolymers were synthesized from the RDRP macroinitiators using a copper(0)-mediated polymerization system at ambient temperature. By controlling the macroinitiator to monomer feeding ratio from 1:50 to 1:100, the resultant copolymers had number average molecular weights (M n) in the range of 7900–17800 g mol−1 with dispersities (Đ) of 1.42-1.52. Afterward, the isocyanate-containing copolymers were employed in the fabrication of particles via interfacial polymerization, followed by a water removal process using spray drying. All polymers and particles were thoroughly characterized using a range of spectroscopic, chromatographic and microscopy analyses. [ABSTRACT FROM AUTHOR]

An approach to the synthesis of the novel molecular brushes with a polyimide (PI) backbone and poly(ε-caprolactone) (PCL) side chains was developed. To obtain such copolymers, a combination of various synthesis methods was used, including polycondensation, atom transfer radical polymerization (ATRP), ring opening polymerization (ROP), and Cu (I)-catalyzed azide-alkyne Huisgen cycloaddition (CuAAC). ATRP of 2-hydroxyethyl methacrylate (HEMA) on PI macroinitiator followed by ROP of ε-caprolactone (CL) provided a "brush on brush" structure PI-g-(PHEMA-g-PCL). For the synthesis of PI-g-PCL two synthetic routes combining ROP and CuAAC were compared: (1) polymer-analogous transformations of a multicenter PI macroinitiator with an initiating hydroxyl group separated from the main chain by a triazole ring followed by ROP of CL, or (2) a separate synthesis of macromonomers with the desirable functional groups (polyimide with azide groups and PCL with terminal alkyne groups), followed by a click reaction. Results showed that the first approach allows to obtain graft copolymers with a PI backbone and relatively short PCL side chains. While the implementation of the second approach leads to a more significant increase in the molecular weight, but unreacted linear PCL remains in the system. Obtained macroinitiators and copolymers were characterized using 1H NMR and IR spectroscopy, their molecular weight characteristics were determined by SEC with triple detection. TGA and DSC were used to determine their thermal properties. X-ray scattering data showed that the introduction of a polyimide block into the polycaprolactone matrix did not change the degree of crystallinity of PCL. [ABSTRACT FROM AUTHOR]

Capillary gel electrophoresis is widely applied for determination of sequence and size of DNA, in which the sieving gel plays an unignorable role. Herein, a pore-size controllable hydrogel was synthesized in the capillary with two symmetrical tetrahedron-like macromonomers consisting of pentaerythritoltetra (succinimidylcarboxypentyl) polyoxyethylene (PS) and pentaerythritoltetra (aminopropyl) polyoxyethylene) (PA). By capillary electrophoresis of the DNA fragments with this hydrogel, it is found that a homogenous structure of hydrogel which is more suitable for the DNA separation can be achieved when the molecular weight of PA is approximate to that of PS. DNA fragments smaller than 1500 bp can be well resolved in this hydrogel within 13 min. More than 100 consecutive runs can be carried out in such a dynamically coated capillary before performance begins to degrade. Notably, such hydrogel can realize separation of dsDNA up to single base pair resolution and same length of dsDNA with 1 bp difference. [Display omitted] • A pore-size controllable hydrogel was synthesized in the capillary. • The DNA markers were well separated in the hydrogel. • Single base pair resolution was realized in capillary filled with this hydrogel. [ABSTRACT FROM AUTHOR]

Branched silicones possess interesting properties as oils, including their viscoelastic behavior, or as precursors to controlled networks. However, highly branched silicone polymers are difficult to form reliably using a "grafting to" strategy because functional groups may be bunched together preventing complete conversion for steric reasons. We report the synthesis of vinyl-functional highly branched silicone polymers based, at their core, on the ability to spatially locate functional vinyl groups along a silicone backbone at the desired frequency. Macromonomers were created and then polymerized using the Piers–Rubinsztajn reaction with dialkoxyvinylsilanes and telechelic HSi-silicones; molecular weights of the polymerized macromonomers were controlled by the ratio of the two reagents. The vinyl groups were subjected to iterative (two steps, one pot) hydrosilylation with alkoxysilane and Piers–Rubinsztajn reactions, leading to high molecular weight, highly branched silicones after one or two iterations. The vinyl-functional products can optionally be converted to phenyl/methyl-modified branched oils or elastomers. [ABSTRACT FROM AUTHOR]

• A hyperbranched polyether- b -amides with controlled amide length was synthesized. • Three-armed N -methylbenzamide pentamer was used as a hard segment. • Poly(ethylene oxide) was used as a soft segment. • Tough and transparent films were prepared. • Good shape memory properties were realized. High-molecular-weight hyperbranched polyether- b -amides (hb -PEBA; number average molecular weight (M n) = 29.2–96.2 kDa) were successfully prepared by polycondensation of NH 2 -terminated poly(ethylene oxide) (PEO; M n = 3.35, 4.6, 8.0, and 10.0 kDa) as A 2 -type and COOH-terminated three-armed N -methylbenzamide pentamers (TMA-3MAB 5) as B 3 -type macromonomers in N -methylpyrrolidone (NMP) at 35–60 °C for 6 h. TMA-3MAB 5 was prepared by stepwise condensation of 4- N -methylaminobenzoic acid (MAB), trimesic acid (TMA), and thionyl chloride/NMP as the building block, core molecule, and condensation reagent, respectively. Transparent to opaque films were prepared from all polymer samples through the solvent casting method using CHCl 3 , and the crystallization of PEO segments (crystallization degree X c 15%–66%) was confirmed using differential scanning calorimetry (DSC). The hb -PEBA films showed tensile strengths of 0.71–16.8 MPa, with breaking elongation of 40–350%, and tensile elastic moduli of 0.10–1.43 GPa, depending on M n and polymer composition. The superior shape memory properties of hb -PEBA polymers compared with their linear counterparts were confirmed by deformation at 80 °C, shape retention (memory) at room temperature, and shape recovery by reheating. Overall, the well-controlled TMA-3MAB 5 was undoubtedly effective for the synthesis of high M n hb -PEBA, resulting in improved mechanical and shape memory properties. [ABSTRACT FROM AUTHOR]

A series of new poly (ethylene glycol) (PEG) segmented poly (arylene ether)s (PAEs), (PEG-PAEs) were synthesized via nucleophilic substitution polycondensation. The prepared PEG-PAEs are thermally stable up to 190 °C, which is dominated by the PEG segments. Their glass transition temperature (T g) points are in the range of -10 - 32 °C, which is dictated by the molecular weights as well as the fraction of PEG segments in the structures. And the materials are in an amorphous state due to the steric hindrance imposed by F1 segments. The rheological measurement reveals that the viscoelastic property of the F-PEG1000 and F-PEG2000 can experience a transition from a glassy state to a leather state and then to a rubbery state after applying the time-temperature superposition (TTS) principle. Moreover, a decreased trend of the complex viscosity is found as the temperature increases, which can be attributed to the accelerated movement of polymer chains at a higher temperature. And the fraction of the PEG segments as well as the molecular weights of the materials can also affect the complex viscosity. Accordingly, the thermal properties and rheological behaviors of the PEG-PAEs can be adjusted by selecting different PEG macromonomers. A series of new poly (ethylene glycol) segmented poly (arylene ether)s were synthesized through nucleophilic substitution polycondensation. The results reveal the feasibility of adjusting their thermal properties and rheological behaviors by selecting different PEG macromonomers. Image 1 • New poly (ethylene glycol) segmented poly (arylene ether)s were synthesized using nucleophilic substitution polycondensation. • All polymers are thermally stable up to 190 C and their T g was related to the selected PEG macromonomers. • The polymers can exhibit the transition from a glassy state to a leather state and then to a rubbery state. [ABSTRACT FROM AUTHOR]

A series of polycarboxylate superplasticizer (PCE) polymers were synthesized from acrylic acid (AA) and isoprenyloxy polyethylene glycol ether (IPEG) at the mole ratios of 3.0, 4.2, 5.0 and 6.0. In this study, the molecular weight properties of PCE polymers were recorded by size exclusion chromatography with the time interval of 1 h. Mini slump test was used to detect the dispersing effectiveness of PCE polymer in cement paste. The results indicated that the reaction rate of monomers, conversion of 52IPEG macromonomer and molecular weight of PCE polymers increased with the general adding ratio of AA to IPEG macromonomers while the side chain density of PCE polymers decreased. PCE polymers possessed molecular weight around 30,000 g/mol with low side chain density, and long main chain length presented high initial dispersing effectiveness at the low dosage around 0.12%. The majority of effective PCE polymers were formed during the adding period of acrylic acid in the first 3 h. [ABSTRACT FROM AUTHOR]