Pendant Double Bonds Research Articles

Biobased Alkali Soluble Resins promoting supramolecular interactions in sustainable waterborne Pressure-Sensitive Adhesives: High performance and removability

Social environmental demands are increasingly promoting the development of low carbon footprint adhesive materials capable of providing excellent properties and ensuring clean removability. Herein, high performance and easy removable waterborne pressure-sensitive adhesives with biobased contents up to 71% stabilized with novel biobased alkali soluble resins (ASRs) have been successfully developed. 2-octyl acrylate (2OA), isobornyl methacrylate (IBOMA) and isosorbide (di)methacrylate (ISOMAraw) are the main biobased monomers used to synthesize the ASR and waterborne polymer dispersions. Pendant double bonds coming from isosorbide dimethacrylate promoted the grafting of the ASR resin, whereas hydrogen-bonding interactions provided by free OH groups create supramolecular interactions improving the viscoelastic character of the polymer network enhancing both the elasticity and energy dissipation of the pressure- sensitive adhesives along a greater range of frequencies (from 10−1 to 103 Hz). Furthermore, the presence of carboxylic groups in the pressure-sensitive adhesive compositions lead to a clean and fast removability of the adhesive tape from the glass substrate in basic media in 20 min. These novel biobased waterborne PSA compositions are ideal candidates for high performance applications where an easy and sustainable detachment after their use are required.

Ferrocene-containing cross-conjugated polymers synthesized by palladium-catalyzed cross-coupling polymerization

We have exploited an extremely efficient and versatile route to prepare ferrocene-containing cross-conjugated polymers (oligomers) in the main-chain. Using a variety of 1,1′-disubstituted ferrocenyl ketone-derived N-tosylhydrazones, reaction with aryl halides under palladium-catalysis gave 14 poly(ferrocenylene-vinylidene) cross-conjugated polymers (oligomers) in 50–80% yield. It was noteworthy that all the polymeric products were well soluble in common organic solvents, endowing them with high solution processability. Pendant double bonds of these cross-conjugated polymers (oligomers) were suitable towards further processing with high reactivity. The optical properties of the polymers (oligomers) were examined. The electrochemical properties of polymers (oligomers) were investigated by cyclic voltammetry (CV) and suggested a quasi-reversible process. Moreover, these cross-conjugated polymers (oligomers) proved thermally stable and demonstrated promising potential as low-migration burning rate catalysts.

Cyclization of 1,n-Enynes Initiated by the Addition Reaction of gem-Dichromiomethane Reagents to Alkynes.

Treatment of 1,n-enynes with gem-dichromiomethane species prepared in situ from 1,1-diiodomethanes and CrCl2 gave alkenylbicycloalkanes. Alkenylcarbene species, which was generated via [2 + 2] cycloaddition with a triple bond, were intercepted by intramolecular cyclopropanation of a pendant double bond, and alkene metathesis did not proceed. This is a very rare example of transformation of alkynyl C≡C with gem-dimetalloalkanes. Silyl- and borylcarbene equivalents generated from gem-(dichromio)silyl- and borylmethanes promoted the coupling and cyclization of enediynes as well as 1,n-enynes.

A polymer-based zwitterionic stationary phase for hydrophilic interaction chromatography

We describe a novel polymer-based zwitterionic stationary phase for hydrophilic interaction chromatography (HILIC). It is prepared by chemical modification of poly (glycidyl methacrylate-divinylbenzene) (GMA-DVB) by converting epoxide groups of microsphere surface to diol groups via hydrolysis, then clicking cysteine onto the microsphere with pendant double bonds of microsphere surface via “thiol-ene” click chemistry. The phase has been characterized by scanning electron micrograph, elemental analysis and zeta potential measurement. Diol and zwitterionic group (carboxylate and amine group associated with cysteine) onto the surface of GMA-DVB microspheres make them possess good hydrophilicity, as supported by effective separation towards common polar analytes. It shows good stability at alkaline solution (e.g. pH 10) and negligible bleed (e.g. only 1.7-fold blank and ~55-fold lower than a commercial silica-based polar phase tested with the minimal bleed level). Such phase exhibits specific separation selectivity to ionic analytes and simultaneous separation of anions and cations is achieved in the retention order of I− < NO3− < Choline < Br− < Cl− < K+< Na+.

Poly(ether-carbonate) based hydrogel with tunable mechanical strength and enhanced bioactivity prepared by Michael addition

Poly (ether-ester) based hydrogels have been broadly used as degradable biomaterials in drug delivery systems and tissue engineering. However, they were synthesized with uncontrollable mechanical properties and inert to most of the biological activities, such as cell adhesion and stem cell differentiation. Herein, we synthesized a water-soluble copolymer with poly (trimethylene carbonate-co-2-methyl,2-methylacrylate-bimethylene carbonate) (PTMAc) and poly(ethylene glycol)(PEG) blocks (PCE), in which the PTMAc segments provided free active double bonds and can be further conjugated with thiol-ended peptides to improve its cytocompatibility. Meanwhile, the extra double bonds were crosslinked by Michael addition, forming hydrogels with precisely controlled mechanical strength. The chemical structure and molecular weight of the synthesized PCE were characterized by 1H NMR and gel permeation chromatography (GPC). The composition of the PCEs was controlled by changing the feed ratios of 2-methyl,2-methylacrylate-bimethylene carbonate (Ac) comonomer (fAc). It was noted that when the ratio of comonomers to the macroinitiator PEG ([M]0/[I]0 = 18) and the ratio of DL-Dithiothreitol (DTT) to Ac ([thiol]/[Ac] = 1/1) were fixed, the storage moduli of PCE hydrogels increased from 2 kPa to 10 kPa and the gelation time decreased with increasing fAc. The pendant double bonds were easily conjugated with CRGD to promote the neurite sprouting and axonal extension from the dorsal root ganglion (DRG) neurons. Moreover, the weaker the hydrogel matrix (G′ = 0.2 kPa) was, the lower the axon extension length was, but the axon diameter became thicker. An increase in modulus is beneficial to axon extension (5 kPa), while a high modulus (10 kPa) is unfavorable. These results demonstrated that this novel poly(ether-carbonate) based hydrogel can be introduced as a suitable scaffold for fast and effective nerve regeneration.

Responsive and Degradable Highly Branched Polymers with Hypervalent Iodine(III) Groups at the Branching Points.

A hypervalent (HV) iodine(III)-containing crosslinker, (diacryloyloxyiodo)benzene, is synthesized and its crystal structure is reported. Highly branched polymers with hypervalent iodine(III) groups as the building blocks present at the branching points are synthesized by copolymerization of tert-butyl acrylate and the diacrylate crosslinker (up to 12 mol% vs the monovinyl monomer), under reversible deactivation radical polymerization (iodine transfer polymerization) conditions, which are employed to ensure that the incorporation of the crosslinker into the polymer chains is slow and gradual, that is, to limit the average number of pendant double bonds per chain and delay gelation. The branched polymers with (diacyloxyiodo)benzene-type linkers are responsive and react with monocarboxylic acids, for example, acetic acid, which participate in ligand-exchange reactions with the HV iodine(III) centers, and with reducing agents, for example, tributylphosphine, which reduce iodine(III) to iodine(I); both reactions lead to polymer degradation with the formation of random linear copolymers of tert-butyl acrylate and acrylic acid.

A poly(glycidylmethacrylate-divinylbenzene)-based anion exchanger for ion chromatography

An anion exchanger has been described by grafting dimethylaminoethyl methacrylate methylchloride (DMC) onto the poly(glycidyl methacrylate-divinylbenzene) (GMA-DVB) subtract. The grafting was performed by coupling of DMC with the pendant double bonds of DVB. Prior to grafting, a hydrolysis treatment to free epoxide groups associated with GMA-DVB substrate enables an improved hydrophilic surface of the obtained anion exchanger. The capacity of the obtained anion exchanger can be manipulated by controlling DMC amount to a great degree. Common seven inorganic anions onto the anion exchanger could be well separated within 20 min and high separation efficiency was obtained, e.g. 46,500/m of the plate count for chloride.

Functional Polyesters with Pendant Double Bonds Prepared by Coordination–Insertion and Cationic Ring-Opening Copolymerizations of ε-Caprolactone with Renewable Tulipalin A

The synthesis of functional copolyesters that contain pendant double bonds in their structures is reported by ring-opening copolymerization of renewable monomer Tulipalin A (α-methylene-γ-butyrolactone, MBL) and e-caprolactone (CL) using either coordination–insertion or monomer activated mechanisms. Aluminum tris(isopropoxide) (Al(OiPr)3) was successfully used as a cheap and commonly available catalyst for the coordination–insertion ring-opening copolymerization, and functional copolyesters with dispersities below 1.2 and with contents of MBL units in the copolymer up to 25 mol % were prepared. In addition, linear or multiarm copolymers of MBL with CL were synthesized by cationic ring-opening copolymerization that was conducted using protic acid as a “metal-free” catalyst in combination with mono- or multihydroxyl alcohols as initiators. The molecular characteristics and composition of the functional copolyesters were determined by GPC, NMR, two-dimensional NMR, and MALDI-TOF spectroscopy. The effect of M...

Poly(ε-caprolactone) networks with tunable thermoresponsive shape memory via a facile photo-initiated thiol–ene pathway

Thermoresponsive shape memory poly(e-caprolactone) (PCL) networks with readily tunable properties are prepared exploiting the facile UV-initiated thiol–ene methodology. PCLs with multiple pendant double bonds at both chain ends are used to cross-link with multi-thiol compounds via photo-initiated thiol–ene reactions. Mechanical and shape memory properties can be altered through changes in the number of alkene side groups at the PCL chain termini and thiol cross-linker structure. In parallel with structural investigation by spectroscopic techniques, the relationships between the composition and material properties are investigated. The PCL thermoset materials exhibit excellent thermoresponsive shape memory performance by changing the operation temperature below or above the melting temperature of crystalline PCL segments, which varies in the range of 34–40 °C, and the highest shape retention and recovery ratios can reach 98–100%.

UV-Curable Antismudge Coatings

Current antismudge coatings that bear nano-pools of a grafted liquid ingredient for dewetting enablement (NP-GLIDE) are cured at high temperatures, which are undesirable for application on heat-sensitive substrates. Reported herein is the development of a NP-GLIDE coating that can be photocured at room temperature. Of the various formulations that have been tested, robust coatings were obtained from one recipe consisting of a photoinitiator, a trifunctional monomer that bears three double bonds, and a graft copolymer. The last bears pendent double bonds and a poly(dimethylsiloxane) (PDMS) side chain as the antismudge agent. Coatings were prepared by casting films from a solution containing these three components and then photolyzing the resultant films. A systematic study revealed that the liquid sliding property developed on the coating at a lower cross-linking density than that required for ink to contract. Further, retaining the ability to contract ink traces after many writing and erasing cycles was the most demanding of the three antismudge tests. For our optimized formulation, only 5 min of irradiation was required to yield a transparent coating with superior antismudge properties. Moreover, irradiating selected regions and then removing, with a solvent, reagents in the nonirradiated regions can yield a surface with patterned wettability. These advantageous properties of the new photocurable coating facilitate its applications.

A Simple and Efficient Protocol for the Catalytic Insertion Polymerization of Functional Norbornenes.

Norbornene can be polymerized by a variety of mechanisms, including insertion polymerization whereby the double bond is polymerized and the bicyclic nature of the monomer is conserved. The resulting polymer, polynorbornene, has a very high glass transition temperature, Tg, and interesting optical and electrical properties. However, the polymerization of functional norbornenes by this mechanism is complicated by the fact that the endo substituted norbornene monomer has, in general, a very low reactivity. Furthermore, the separation of the endo substituted monomer from the exo monomer is a tedious task. Here, we present a simple protocol for the polymerization of substituted norbornenes (endo:exo ca. 80:20) bearing either a carboxylic acid or a pendant double bond. The process does not require that both isomers be separated, and proceeds with low catalyst loadings (0.01 to 0.02 mol%). The polymer bearing pendant double bonds can be further transformed in high yield, to afford a polymer bearing pendant epoxy groups. These simple procedures can be applied to prepare polynorbornenes with a variety of functional groups, such as esters, alcohols, imides, double bonds, carboxylic acids, bromo-alkyls, aldehydes and anhydrides.

Copolymerization of Ethylene with 1,9‐Decadiene: Part I – Prediction of Average Molecular Weights and Long‐Chain Branching Frequencies

Long chain branches improve the viscoelastic properties of polyolefins and make them easier to process. The frequency of long chain branching in polyethylenes made with coordination catalysts can be substantially increased by copolymerizing ethylene with small amounts of nonconjugated dienes using an adequate catalyst. In this work, the kinetics of copolymerization of ethylene and 1,9‐decadiene is investigated using a constrained geometry catalyst in a solution polymerization semi‐batch reactor, and a novel mathematical model is proposed to describe the resulting molecular weight distributions. A hybrid approach, combining particle swarm optimization, parameter identifiability procedures, and the Gauss–Newton method is applied to estimate the model parameters. The proposed mechanism includes macromonomer reincorporation through pendant double bonds that result from diene incorporation. The predicted long chain branching frequencies are validated by Monte Carlo simulation. Experimental average molecular weights and ethylene feed flow rates are successfully predicted by both methods. image

Morphogenesis of Photo-Polymerized Dimethacrylate Networks, Kinetics of Curing and Viscoelastic Parameters

The paper refers to the process of dimethacrylate networks morphogenesis. These stiff and highly cross-linked networks have been extensively used as a polymeric matrix of dental composites for decades. In the study, common co-monomer mixtures used in dental resin formulations were employed. This includes rigid aromatic base monomers, bisphenol A glycerolate dimethacrylate (Bis-GMA) and its ethoxylated alternative (Bis-EMA). Flexible aliphatic monomer, triethylene glycol dimethacrylate (TEGDMA), was used as the viscosity reducer. Kinetics of the polymerization process was studied regarding the structural differences and varying molar ratio of the co-monomers. Kinetic data provided the base for understanding the supra-molecular structure evolution. Consequently, an attempt to quantify the relationship between the resulting network morphology and complex viscoelastic moduli was made. Curing kinetics was studied using differential photo-calorimetry (DPC). Complex modulus was measured using dynamic-mechanical analysis (DMA). Thermal degradation kinetic data (TGA) were used in order to confirm the estimated morphology of cured networks. Reactivity of the monomer is derived from its molecular structure. The potential for non-covalent physical interactions along with monomer backbone rigidity significantly decrease polymerization rate and resulting double bond conversion. The diffusion-controlled kinetics dominates over the chemically controlled kinetics throughout most of the polymerization process. Dilution by the low viscous and flexible monomer shifts the diffusion-controlled kinetics to the later stages of the polymerization. However, the flexibility of the monomer backbone promotes the origination of structural heterogeneities, characterized by micro-gel domains formation. This is associated particularly with the anomalous pendant double bond reactivity and ineffective cross-linking.

Toward Understanding of Branching in RAFT Copolymerization of Methyl Methacrylate through a Cleavable Dimethacrylate

We report the reversible addition–fragmentation chain transfer (RAFT) solution copolymerization of methyl methacrylate (MMA) with a cleavable divinyl comonomer, bis(2-methacryloyl)oxyethyl disulfide (BMAODS). 2-Cyano-2-propyldodecyl trithiocarbonate was used as a RAFT chain transfer agent and 2,2′-azobis(2-methylpropionitrile) as an initiator. The selective cleavage of BMAODS disulfide bonds was used to collect primary chains for the determination of the branching density (BD). The effects of initial monomer concentration, vinyl/divinyl ratio, and primary chain length on the branching and cyclization reactions were thoroughly investigated. It was found that more than 50% pendent double bonds from BMAODS were consumed in cyclization rather than in branching. The BD increased linearly with the conversion up to approximately 60% conversion. The monomer concentration was found to be the most efficient parameter in promoting branching. Increasing divinyl monomer ratio and primary chain length favored cyclizati...

Facile synthesis of functional copolymers with pendant vinyl groups by using asymmetrical divinyl monomers

ABSTRACTPolymers bearing pendant vinyl groups have attracted significant attraction because they can be further modified for required applications, but their syntheses are still a big challenge. Herein, allyl methacrylate was catalyzed using a phosphazene base to homopolymerize or copolymerize with 2‐(N, N‐dimethylamino) ethyl methacrylate, affording vinyl functional polymers, which were further successfully tailored by the thiol–ene coupling reaction. The result showed that both the homopolymerizations and copolymerizations could proceed at room temperature with very high monomer conversions. The contents of pendant double bonds in the copolymers were approximately equal to the monomer feeds, but the LCST of the statistical copolymers linearly decreased with increasing AMA content. This strategy offered a new scalable and facile strategy for vinyl functional polymers, would have a wide practical application in many fields. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42758.

Chemoselective, Stereospecific, and Living Polymerization of Polar Divinyl Monomers by Chiral Zirconocenium Catalysts.

This contribution reports the first chemoselective, stereospecific, and living polymerization of polar divinyl monomers, enabled by chiral ansa-zirconocenium catalysts through an enantiomorphic-site controlled coordination-addition polymerization mechanism. Silyl-bridged-ansa-zirconocenium ester enolate 2 has been synthesized and structurally characterized, but it exhibits low to negligible activity and stereospecificity in the polymerization of polar divinyl monomers including vinyl methacrylate (VMA), allyl methacrylate (AMA), 4-vinylbenzyl methacrylate (VBMA), and N,N-diallyl acrylamide (DAA). In contrast, ethylene-bridged-ansa-zirconocenium ester enolate 1 is highly active and stereospecific in the polymerization of such monomers including AMA, VBMA, and DAA. The polymerization by 1 is perfectly chemoselective for all four polar divinyl monomers, proceeding exclusively through conjugate addition across the methacrylic C═C bond, while leaving the pendant C═C bonds intact. The polymerization of DAA is most stereospecific and controlled, producing essentially stereoperfect isotactic PDAA with [mmmm] > 99%, M(n) matching the theoretical value (thus a quantitative initiation efficiency), and a narrow molecular weight distribution (Đ = 1.06-1.16). The stereospecificity is slightly lower for the AMA polymerization but still leading to highly isotactic poly(allyl methacrylate) (PAMA) with 95-97% [mm]. The polymerization of VBMA is further less stereospecific, affording PVBMA with 90-94% [mm], while the polymerization VMA is least stereospecific. Several lines of evidence from both homo- and block copolymerization results have demonstrated living characteristics of the AMA polymerization by 1. Mechanistic studies of this polymerization have yielded a monometallic coordination-addition polymerization mechanism involving the eight-membered chelating intermediate. Post-functionalization of isotactic polymers bearing the pendant vinyl group on every repeating unit via the thiol-ene "click" reaction achieves a full conversion of all the pendant double bonds to the corresponding thioether bonds. Photocuring of such isotactic polymers is also successful, producing an elastic material readily characterizable by dynamic mechanical analysis.

Synthesis of sulfur-containing alternating copolymers by RAFT copolymerization of phenyl vinyl sulfides

An electron-donating S-vinyl monomer, phenyl vinyl sulfide (PVS), was copolymerized with electron-accepting monomers, such as maleic anhydride (MA), N-methyl maleimide (MMI), and N-phenyl maleimide (PMI), via a reversible addition–fragmentation chain transfer (RAFT) process. Among various chain transfer agents (CTAs), the trithiocarbonate-type CTA was found to be effective in achieving controlled copolymerizations of PVS with the electron-accepting monomers with a strong alternating tendency. The controlled nature of the RAFT copolymerization of PVS with PMI was confirmed by the formation of narrow polydispersity products, with the molecular weight being controlled by the monomer/CTA molar ratio, resulting in an observed linear increase in the molecular weight with the polymer yield. RAFT copolymerization of PVS with an asymmetrical divinyl monomer, N-vinyl maleimide, in the presence of the trithiocarbonate-type CTA allowed the synthesis of alternating copolymer with pendant double bonds, which were available for subsequent thiol-ene click reaction to produce novel sulfur-containing copolymers.

Living Anionic Polymerization of Functional Aziridines

Summary2‐(Oct‐7‐en‐1‐yl)‐N‐mesylaziridine was used as a novel monomer for the anionic ring‐opening polymerization. This is the first functional aziridine‐derivative that can be polymerized via an anionic mechanism. Homo‐ and copolymers with (2‐n‐decyl‐N‐mesylaziridine) were synthesized and characterized via NMR spectroscopy and SEC. Molecular weight distributions were all monomodal and very narrow (Mw/Mn &lt; 1.1). The pendant double bonds were functionalized with a protected cysteine derivative as a model for potential bioconjugation.

Unsaturated Polyesters with Pendant Double Bonds and Investigation of their Self Curable Activity

In this paper, the self-curable unsaturated polyester was put forward as a new solution to air pollution problems caused by the cross-linking monomer’s volatilization in unsaturated polyesters (UP) industry. Two kinds of unsaturated polyesters with the vinyl double bonds at the side chain were synthesized with Itaconic acid (IA) or Itaconic anhydride (ITA) as raw materials. The first one was prepared with IA, isophthalic acid and propylene glycol (IPP-UP), and the second one was synthesized with glycidol (GL) and ITA (IG-UP). Investigation demonstrates that the latter UP resin could be self-cured through the nucleophilic addition reaction of hydroxyl groups with double bonds or the free-radical homopolymerization of double bonds when they were heated without cross-linking monomers. However, the former couldn’t. Factors on self-crosslinking activity and crosslinking mechamism of pendant vinyl bonds from IA or ITA were explored.1H-NMR and FT-IR were used to characterize.

Mechanistic investigation of the simultaneous addition and free-radical polymerization in batch miniemulsion droplets: Monte Carlo simulation versus experimental data in polyurethane/acrylic systems

A detailed kinetic Monte Carlo simulation was used to predict the characteristics of the batch miniemulsion polymerization of an isocyanate and an acrylic monomer mixture that contains a hydroxyl functional monomer (HEMA). The simulation takes into account the simultaneous polyaddition of the polyurethane prepolymer with the hydroxyl group of HEMA and the free radical polymerization of the acrylic monomers and all reactions in aqueous and polymer particle phases. The model has been assessed by batch miniemulsion polymerizations carried out using an aliphatic isocyanate prepolymer, n-butyl acrylate, 2-hydroxyethyl methacrylate monomers and potassium persulfate as an initiator. It was found that partitioning of water had a significant effect on both kinetics and microstructure of the resulting polymer. Evolution of different species of PU prepolymer produced in the reaction and the sol and gel fractions revealed that the terminal pendent double bond of the HEMA in polymer chains has significantly lower reactivity than that of the HEMA free monomer. Detailed information on gel microstructure has been derived in the model by both distribution of molecular weight between crosslinking points in acrylic chains and distribution of chain extension of PU prepolymers. These crosslinking density distributions can be related to mechanical and adhesive properties of the polymer.