Terminal Acrylate Research Articles

Accelerated ion transportation in liquid crystalline polymer networks for superior solid-state lithium metal batteries

The application of solid polymer electrolyte in high energy density lithium metal batteries is limited by low Li+ mobility, low ionic conductivity and poor cycle stability at room temperature. In the study, the free-standing flexible polymeric electrolytes (PCREs) with semi-interpenetrating-network in the topological nanostructures were fabricated through the in-situ UV-photopolymerization of the liquid crystalline monomers and poly(ethylene glycol) diglycidyl ether. Remarkably, by optimizing the relative proportion of the two liquid crystalline monomers with different methylene chains as connected bridge band between rigid center and terminal acrylate functional groups, the electrochemical properties of the prepared PCREs were successfully improved, which might contributed to the suitable ion transport channels in the porous polymer network structures. The prepared PCRE exhibited increased ion migration number, excellent ionic conductivity and a wide electrochemical window. Through the calculation of density functional theory and molecular dynamics simulation, the difference in the molecular orbital of liquid crystalline polymers and the mechanism of PCREs enhancement tLi+ were well understood. The study may provide new perspectives for the design and fabrication of high-performance polymer electrolyte materials, which will promote the development and practical application of the all-solid lithium metal batteries.

Enhancing the Activity of Surface Immobilized Antimicrobial Peptides Using Thiol-Mediated Tethering to Poly(ethylene glycol).

Considering the need for versatile surface coatings that can display multiple bioactive signals and chemistries, the use of more novel surface modification methods is starting to emerge. Thiol-mediated conjugation of biomolecules is shown to be quite advantageous for such purposes due to the reactivity and chemoselectivity of thiol functional groups. Herein, the immobilization of poly(ethylene glycol) (PEG) and antimicrobial peptides (AMPs) to silica colloidal particles based on thiol-mediated conjugation techniques, along with an assessment of the antimicrobial potential of the functionalized particles against Pseudomonas aeruginosa and Staphylococcus aureus is investigated. Immobilization of PEG to thiolated Si particles is performed by either a two-step thiol-ene "photo-click" reaction or a "one-pot" thiol-maleimide type conjugation using terminal acrylate or maleimide functional groups, respectively. It is demonstrated that both immobilization methods result in a significant reduction in the number of viable bacterial cells compared to unmodified samples after the designated incubation periods with the PEG-AMP-modified colloidal suspensions. These findings provide a promising outlook for the fabrication of multifunctional surfaces based upon the tethering of PEG and AMPs to colloidal particles through thiol-mediated biocompatible chemistry, which has potential for use as implant coatings or as antibacterial formulations that can be incorporated into wound dressings to prevent or control bacterial infections.

Bulky Cyclometalated Ruthenium Nitrates for Challenging Z-Selective Metathesis: Efficient One-Step Access to α-Oxygenated Z-Olefins from Acrylates and Allyl Alcohols.

α-Oxygenated Z-olefins are ubiquitous in biologically active molecules and serve as versatile handles for organic synthesis, but their syntheses are often tedious and less selective. Here we report the efficient Z-selective metathesis of various terminal acrylates and allyl alcohols, which enables facile and selective construction of high value-added α-oxygenated Z-olefins from readily available feedstock chemicals. These challenging metathesis transformations are enabled by novel cyclometalated Ru-carbene-nitrate complexes bearing bulky-yet-flexible side arms, whose assembly was unlocked by new organometallic syntheses.

Bulky Cyclometalated Ruthenium Nitrates for Challenging Z‐Selective Metathesis: Efficient One‐Step Access to α‐Oxygenated Z‐Olefins from Acrylates and Allyl Alcohols

Abstractα‐Oxygenated Z‐olefins are ubiquitous in biologically active molecules and serve as versatile handles for organic synthesis, but their syntheses are often tedious and less selective. Here we report the efficient Z‐selective metathesis of various terminal acrylates and allyl alcohols, which enables facile and selective construction of high value‐added α‐oxygenated Z‐olefins from readily available feedstock chemicals. These challenging metathesis transformations are enabled by novel cyclometalated Ru‐carbene‐nitrate complexes bearing bulky‐yet‐flexible side arms, whose assembly was unlocked by new organometallic syntheses.

Synthesis, characterization, and photopolymerization of (meth)acrylate‐functional polyisobutylene macromers produced by cleavage/alkylation of butyl rubber

AbstractLinear, multi‐functional polyisobutylene (PIB) macromers bearing pendent and terminal (meth)acrylate moieties were prepared via electrophilic cleavage/alkylation of butyl rubber in the presence of (3‐bromopropoxy)benzene, followed by displacement of the resulting bromide moieties with potassium (meth)acrylate. Number average functionality (Fn) ranged from 2.8–7.9; functional equivalent weights ranged from 2.3–4.7 kg/mol. For comparison, a three‐arm, end‐functional PIB triacrylate with equivalent weight of 3.3 kg/mol was also synthesized via living polymerization and end quenching with 4‐phenoxy‐1‐butyl acrylate. All polymers were photocured using Darocur 1173 photoinitiator, and curing kinetics were monitored by real time Fourier‐transform infrared spectroscopy. All systems reached ~100% conversion by 1,800 s, but the linear macromers displayed slower curing rates compared to the PIB triacrylate. The curing rate of linear macromers increased as molecular weight decreased. Cured networks were characterized using dynamic mechanical analysis and tensile testing. Tensile strength varied from 0.15–0.80 MPa. Young's modulus varied from 0.13–1.8 MPa. Strain at break for most networks ranged from 34–54%, but the network derived from the lowest molecular weight PIB reached 113% at failure. Percent extractables, measured using solvent extraction, was about 2% for linear macromers and about 4% for PIB triacrylate.

Synthesis and Evaluation of Cytocompatible Alkyne-Containing Poly(β-amino ester)-Based Hydrogels Functionalized via Click Reaction.

Although poly(β-amino esters) (PAEs) have been widely applied in nonviral gene transfection, drug delivery systems, and regenerative medicine, the multifunctional modification of PAEs and bio-orthogonal strategies of PAE-based hydrogel functionalization is still a challenge. Herein, a strategy of poly(β-amino ester)-based hydrogel functionalization was developed via bio-orthogonal reactions in this study. Acrylate-terminated poly(β-amino esters) containing alkyne groups were synthesized by Michael addition reaction. Alkyne groups on poly(β-amino esters) could conjugate bioactive molecules with azide of K(N3)RGD via copper-catalyzed azide-alkyne cycloaddition, and terminal acrylate groups could in situ polymerize to prepare a hydrogel. A biomimetic peptide K(N3)RGD functionalized hydrogel was prepared by polymerization of acrylate-terminated poly(β-amino esters) containing conjugated peptide and polyethylene glycol diacrylate (PEGDA). The storage modulus and mechanical properties exhibited an increased trend with the increased concentration; nevertheless, swelling ratio and surface wetting properties demonstrated a decreased tendency by increased concentrations. Cell proliferation and live/dead staining showed that Schwann cells plated on the hydrogel with an elastic modulus of 25.39 KPa are more suitable for proliferation and function exertion of Schwann cells compared with that of 42.11 and 57.86 KPa, and KRGD-conjugated hydrogel could increase the elongation of Schwann cells relative to nonconjugated hydrogels. This azide-alkyne strategy may be a promising candidate for hydrogel functionalization in tissue engineering and other biomedical applications.

Fabrication of unimolecular micelle-based nanomedicines from hyperbranched polymers containing both terminal and internal reactive groups

Unimolecular micelles are an attractive type of nanocarriers for drug delivery, but developing unimolecular micelle-based nanomedicine with high drug loading capacity and excellent unimolecular stability is challenging. Herein, we report the design and synthesis of hyperbranched polymers containing both terminal and internal reactive groups for fabricating the unimolecular micelle-based nanocarriers with high drug loading ability and superior unimolecular stability using selective modification. Specifically, we synthesized hyperbranched poly(amino ester)s containing terminal acrylate groups and internal R groups (named HBPAE-R) via the Michael addition polymerization of A2 + BʹB2-R monomers, wherein A represents acrylate, and B, Bʹ represents the hydrogen in primary amine and secondary amine group, respectively, whereas R represents hydroxy, alkene or alkyne groups that do not participate in the polymerization process but assist in additional modification. Then, poly(ethylene glycol) (PEG) chains were linked to the surface of HBPAE-OH (representative molecules) with the subsequent conjugation of doxorubicin (DOX, representative drug) to the internal hydroxy groups through an acid-labile hydrazide bond, to afford anti-cancer drug-loaded hyperbranched star copolymers PEG-HBPAE-DOX. The obtained nanomedicines exhibited good unimolecular stability, relatively high drug loading content and a controlled drug release behavior. The in vitro cytotoxicity experiments further demonstrated the anti-tumor efficacy of these unimolecular nanomedicines. Our approach is expected to further boost research on the fabrication of multifunctional unimolecular nanomedicines from hyperbranched polymers containing both terminal and internal reactive groups.

Preparation of Degradable Polymenthide and Its Elastomers from Biobased Menthide via Organocatalyzed Ring-opening Polymerization and UV Curing

Development of degradable polyester elastomers plays an important role in the applications of soft mateirals. Noncrystalline polymenthides (PMs) from menthol derived lactone monomers are excellent soft segments for preparing degradable polyester elastomers. By using cyclic trimeric phosphazene base (CTPB) as an organocatalyst, we successfully synthesized PMs with different molecular weights (8.2 kDa to 100.7 kDa) in high yields via ring-opening polymerization (ROP) of menthide. When a CTPB/urea binary catalytic system was adopted, the polymerizations proceeded in a more controlled manner. Using glycerol as initiator, star shaped PMs with well-defined structure were synthesized and subsequently end-capped by acrylate. UV irradiation of the terminal acrylate groups in the star-shaped PMs resulted in formation of chemically cross-linked polyester elastomers without heat or other stimuli. The obtained polyester elastomers exhibit matched modulus (3.8–5.5 MPa), tensile strength (0.56–0.68 MPa), and strain at break (280%–320%) with soft body tissues, displaying great potential in biomedical applications.

Photo-stable cross-linked micron bead with functionalized quantum via suspension polymerization for color conversion

Acrylate groups were introduced on quantum dots (QD) via ligand exchange followed by nucleophilic reaction. The QDs were then polymerized with other multi-functional acrylic monomers in this study. Two acrylate groups were introduced at the end of an elongated ligand and the ligands with two acrylate groups were fully coordinated on the entire surface of the QD. This ligand modification scheme made the QDs highly reactive and also compatible with common organic solvents. No decrease in the quantum yield of the QDs was observed after ligand modification and the adduction reaction. The acrylate functional groups in the QDs were verified by 1H NMR and FT-IR. The prepared QDs with a terminal acrylate group were reacted with trimethylolpropane triacrylate and 1,6-hexanediol diacrylate to form micrometer scale beads via suspension polymerization. The diameter of the spherical beads was in the range of 80–150 μm and QDs 13 nm in diameter were found to be evenly dispersed in the polymer beads. The QD-polymer beads were applied to color conversion layers (CCL) on a blue light emitting diode (LED). The QD-polymer beads showed a 50% reduction over 72 h from the initial optical efficiency, while the QD embedded in the PMMA matrix (QD-PMMA) was reduced by 50% for 14 h.

Hydrosilylation of Reactive Quantum Dots and Siloxanes for Stable Quantum Dot Films.

The reactive acrylate-terminated CdZnSeS/ZnS quantum dots (QDs) were designed and prepared by the effective synthetic route to bond with a siloxane matrix via hydrosilylation. The conventional QD with oleic acid ligands does not have any reactivity, so the QDs were functionalized to assign reactivity for the QDs by the ligand modification of two step reactions. The oleic acid of the QDs was exchanged for hydroxyl-terminated ligands as an intermediate product by one-pot reaction. The hydroxyl-terminated QDs and acrylate-containing isocyanates were combined by nucleophilic addition reaction with forming urethane bonds and terminal acrylate groups. No degradation in quantum yield was observed after ligand exchange, nor following the nucleophilic addition reaction. The modification reactions of ligands were quantitatively controlled and their molecular structures were precisely confirmed by FT-IR and 1H-NMR. The QDs with acrylate ligands were then reacted with hydride-terminated polydimethylsiloxane (H-PDMS) to form a QD-siloxane matrix by thermal curing via hydro-silylation for the first time. The covalent bonding between the QDs and the siloxane matrix led to improvements in the stability against oxygen and moisture. Stability at 85 °C and 85% relative humidity (RH) were both improved by 22% for the QD-connected siloxane QD films compared with the corresponding values for conventional QD-embedded poly(methylmethacrylate) (PMMA) films. The photo-stability of the QD film after 26 h under a blue light-emitting diode (LED) was also improved by 45% in comparison with those of conventional QD-embedded PMMA films.

Preparation of novel side-chain fluoroalkyl polyether oligomers with terminal acrylate for emulsion copolymerization and application on cotton fabric finishing

Three novel side-chain fluoroalkyl polyether oligomers with different molecular weight were synthesized base on the ring-opening polymerization of 3-perfluoro-n-butyl-1,2-epoxypropane, followed by terminal esterification using acryloyl chloride. The oligomer intermediates were used as functional monomers for emulsion copolymerization with methyl methacrylate, butyl acrylate, and hydroxyethyl methacrylate. The produced latexes were used for hydrophobic and oil-phobic finishing on cotton fabric surface and the treated cotton fabrics were tested by scanning electron microscopy and energy-dispersive spectroscopy, combined with chemical composition analysis by X-ray photoelectron spectroscopy. The result showed that fluorinated copolymers were successfully coated on the cotton fibers’ surface. Water contact angles was used to evaluate the wettability and the results showed that treated cotton fabrics possessed good hydrophobicity with the contact angle of 139.1 ± 1°, and the heat resistance of treated cotton fabrics was identified improved through the thermogravimetric analyses (TGA).

Palladium catalyzed cross-dimerization of terminal acetylenes and acrylates

A palladium catalyzed oxidative cross-coupling reaction between terminal alkynes and acrylates was developed. In the presence of palladium catalyst and copper(II) acetate as oxidant, the cross dimerization products with were formed. This protocol provides a novel method to construct the tetrasubstituted functionalized alkenes.

Poly(urethane-acrylate) aerogels from the isocyanurate trimer of isophorone diisocyanate

Poly(urethane acrylate) aerogels were synthesized from radical polymerization of a dendritic monomer having an isocyanurate-based rigid/aliphatic core, urethane linkages and nine terminal acrylate groups. The rigidity of the core comes from the triisocyanate, an isophorone diisocyanate trimer (IPDI). The material properties of those aerogels were compared to the properties of related literature materials derived from triisocyanates with flexible/aliphatic or rigid/aromatic cores, bearing (a) three, or (b) nine terminal acrylate groups. Data support that material properties such as the primary particle size and the BET surface areas are determined mainly by the degree of crosslinking (i.e., the monomer multifunctionality), while the molecular rigidity vs flexibility of the triisocyanate core plays only a secondary role. Addition of ethylene glycol dimethacrylate (EG) in the sol as a chain extender increased the hydrophilicity of the aerogels and their ability to absorb water.

Poly(Urethane-Acrylate) Aerogels via Radical Polymerization of Dendritic Urethane-Acrylate Monomers.

The purpose of this work was to investigate the effect of multifunctionality on material properties of synthetic polymer aerogels. For this purpose, we present the synthesis and characterization of monolithic dendritic-type urethane-acrylate monomers based on an aliphatic/flexible (Desmodur N3300), or an aromatic/rigid (Desmodur RE) triisocyanate core. The terminal acrylate groups (three at the tip of each of the three branches, nine in total) were polymerized with 2,2′-azobis(isobutyronitrile) (AIBN) via free radical chemistry. The resulting wet-gels were dried with supercritical fluid (SCF) CO2. Aerogels were characterized with ATR-FTIR and solid-state 13C NMR. The porous network was probed with N2-sorption and scanning electron microscopy (SEM). The thermal stability of aerogels was studied with thermogravimetric analysis (TGA). Most aerogels were macroporous materials (porosity > 80%), with high thermal stability (up to 300 °C). Aerogels were softer at low monomer concentrations and more rigid at higher concentrations. The material properties were compared with those of analogous aerogels bearing only one acrylate moiety at the tip of each branch and the same cores, and with those of analogous aerogels bearing norbornene instead of acrylate moieties. The nine-terminal acrylate-based monomers of this study caused rapid decrease of the solubility of the growing polymer and made possible aerogels with much smaller particles and much higher surface areas. For the first time, aliphatic/flexible triisocyanate-based materials could be made with similar properties in terms of particle size and surface areas to their aromatic/rigid analogues. Finally, it was found that with monomers with a high number of crosslinkable groups, material properties are determined by multifunctionality and thus aerogels based on 9-acrylate- and 9-norbornene-terminated monomers were similar. Materials with aromatic cores are carbonizable with satisfactory yields (20–30% w/w) to mostly microporous materials (BET surface areas: 640–740 m2 g−1; micropore surface areas: 360–430 m2 g−1).

Double-Cross-Linked Hydrogel Strengthened by UV Irradiation from a Hyperbranched PEG-Based Trifunctional Polymer.

Conventional wound healing materials suffer from low efficiency, poor mechanical strength, and nontunable properties. Responsive hydrogels are appealing candidates for tissue engineering. Herein, we developed a double-cross-linked hydrogel system composed of hyperbranched PEG-based polymer, comprising pre-cross-linked acetal structure and numerous terminal acrylate groups, which can form hydrogels in situ and can be further strengthened by UV irradiation. The hyperbranched glycidyl methacrylate-co-poly(ethylene glycol) diacrylate polymers (HB-GMA-PEGs) were first synthesized via in situ deactivation enhanced atom transfer radical polymerization (DE-ATRP). A series of pre-cross-linked materials were achieved after postfunctionalization. The material can absorb a high amount of water to form hydrogels, and the gel stiffness was evaluated in detail before and after UV irradiation. The in vitro cytotoxicity experiments were conducted with the resulting materials and have demonstrated their good biocompatibility. The results indicate that this type of hydrogel with high water uptake capacity has appealing potential as a responsive biomaterial for wound closure.

Hyperbranched Aliphatic Polyester via Cross-Metathesis Polymerization: Synthesis and Postpolymerization Modification.

A novel postpolymerization modification methodology is demonstrated to achieve selective functionalization of hyperbranched polymer (HBP). Terminal and internal acrylates of HBP derived from cross-metathesis polymerization (CMP) are functionalized in a chemoselective fashion using the thiol-Michael chemistries. Model reactions between different thiols (benzyl mercaptan and methyl thioglycolate) and acrylates (n-hexyl acrylate and ethyl trans-2-decenoate) by using dimethylphenylphosphine or amylamine as the catalyst are investigated to optimize the modification protocol for HBP. High-molecular-weight HBP P0 is generated through CMP of AB2 monomer 2, a compound containing one α-olefin and two acrylate metathetically polymerizable groups. CMP kinetics is monitored by NMR and gel permeation chromatography (GPC). Accordingly, microstructural analysis is conducted in detail, and CMP procedure is optimized. Postpolymerization modification of HBP P0 is performed via two distinguished strategies, namely one-step complete modification and sequential modification, to generate terminally and/or internally functionalized HBPs P1-P3 in a chemoselective fashion by using phosphine-initiated and/or base-catalyzed thiol-Michael chemistries. Finally, thermal stability and glass transition behaviors of HBPs P0-P3 are studied by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively.

Effect of fluorine groups and different terminal chains on the electro-isomerization of azobenzene liquid crystals**Project supported by the National Natural Science Foundation of China (Grant Nos. 61435008 and 61575063).

A series of azobenzene liquid crystals with one or two terminal acrylate groups were synthesized and their polymers were fabricated. The azobenzene liquid crystals and their polymers achieved the photoisomerization from the liquid crystalline trans-isomer to the isotropic cis-isomer with UV irradiation. Then, the cis to trans isomerization induced by an electric field was studied, the time required for electro-isomerization was measured, the texture change and absorption variation from cis to trans form induced by the electric field were observed clearly, and the time required for electro-isomerization was much shorter than that for thermal relaxation. The influence of the polar group (fluorine), terminal acrylate group, and flexible alkyl chain on the time of electro-isomerization was studied. The results show that the compounds with polar fluorine group require shorter time for electro-isomerization and the polymerization of terminal acrylate group delays the electro-isomerization.

Low Molecular Weight PEI-Based Vectors via Acid-Labile Ortho Ester Linkage for Improved Gene Delivery.

A series of novel pH-sensitive gene delivery vectors (POEI 1, 2, and 3) are synthesized through Michael addition from low molecular weight PEI (LMW PEI) via acid-labile ortho ester linkage with terminal acrylates (OEAc) by various feed molar ratios. The obtained POEI 1 and POEI 2 can efficiently condense plasmid DNA into nanoparticles with size range of 200-300 nm and zeta-potentials of about +15 mV while protecting DNA from enzymatic digestion compared with POEI 3. Significantly, ortho ester groups of POEI main-chains can make an instantaneous degradation-response to acidic endosomal pH (≈5.0), resulting in accelerated disruption of polyplexes and intracellular DNA release. MTT assay reveals that all POEIs exhibit much lower cytotoxicity in different cells than branched PEI (25 KDa). As expected, POEI 1 and POEI 2 perform improved gene transfection in vitro, suggesting that such polycations might be promising gene vectors based on overcoming toxicity-efficiency contradiction.

Amine–imine palladium catalysts for living polymerization of ethylene and copolymerization of ethylene with methyl acrylate: incorporation of acrylate units into the main chain and branch end

A bulky amine–imine palladium catalyst can polymerize ethylene in a living fashion. Copolymerizations of ethylene and methyl acrylate afford branched copolymers with terminal and main chain acrylate units.

Novel ABC miktoarm star terpolyphosphoesters: Facile construction and high‐flame retardant property

ABSTRACTA combination of ring‐opening metathesis polymerization (ROMP), ring‐opening polymerization (ROP), and acyclic diene metathesis (ADMET) polymerization approach was first time utilized in the preparation of novel ABC miktoarm star terpolyphosphoesters (PPEs). Acrylate‐terminated monotelechelic PPE was first prepared through ROMP of 7‐membered cyclic phosphate monomer in the presence of a terminating agent, and then terminal acrylate group was readily converted, by thiol‐Michael addition click reaction and esterification, to a heterodifunctional PPE with hydroxyl and acrylate groups, which was a key precursor for the preparation of ABC miktoarm terpolymers. ROP of the cyclic phosphoester monomer initiated by this PPE was successively carried out to generate the acrylate‐functionalized block PPE, which utilized as a selective macromolecular chain stopper in subsequent ADMET polymerization of α,ω‐diene phosphate monomer, finally producing miktoarm terpolyphosphoester. These prepared miktoarm star terpolyphosphoesters demonstrated superior thermal and flame retardant properties via TGA, limiting oxygen index, and microscale combustion calorimetry tests. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 692–701