Terminal Acrylate Research Articles

Synthesis of Degradable Functional Poly(ethylene glycol) Analogs as Versatile Drug Delivery Carriers

Poly(ethylene glycol) (PEG) is widely used as a water soluble carrier for polymer-drug conjugates. Herein, we report degradable linear PEG analogs (DPEGs) carrying multifunctional groups. The DPEGs were synthesized by a Michael addition based condensation polymerization of dithiols and PEG diacrylates (PEGDA) or dimethacrylates (PEGDMA). They were stable at pH 7.4 but quickly degraded at pH 6.0 and 5.0. Thus, DPEGs could be used as drug carriers without concern for their retention in the body. DPEGs could be made to carry such functional groups as terminal thiol or (meth)acrylate and pendant hydroxyl groups. The functional groups were used for conjugation of drugs and targeting groups. This new type of PEG analog will be useful for drug delivery and the PEGylation of biomolecules and colloidal particles.

One‐Pot Difunctionalization of Poly(ω‐pentadecalactone) with Thiol‐Thiol or Thiol‐Acrylate Groups, Catalyzed by Candida antarctica Lipase B

AbstractSummary: An enzymatic one‐pot procedure has been developed for the synthesis of difunctional polyesters containing terminal thiols and acrylates. Candida antarctica lipase B was used as a catalyst for the ring‐opening polymerization of ω‐pentadecalactone. The polymerization was initiated with 6‐mercaptohexanol, then terminated with γ‐thiobutyrolactone or vinyl acrylate to create two types of difunctional polyesters with a very high content of thiol‐thiol or thiol‐acrylate end‐groups.Difunctionalization of poly‐PDL.magnified imageDifunctionalization of poly‐PDL.

Reaction kinetics and microgel particle size characterization of ultraviolet‐curing unsaturated polyester acrylates

AbstractThe free‐radical reaction kinetics and microgel formation of UV‐curing unsaturated polyester acrylates were studied in terms of the effects of internal maleic and terminal acrylate unsaturations. A triacrylate‐functional monomer, trimethylolpropane triacrylate, was used as the reactive diluent. A time‐resolved Fourier transform infrared technique was used to evaluate the consumption of double bonds and showed that internal (maleic) double bonds were involved in microgel formation at a rate similar to that of the more reactive terminal (acrylic) double bonds. Dynamic light scattering was used to measure the microgel particle size. The introduction of internal unsaturations caused smaller microgels, whereas terminal acrylate unsaturations resulted in larger particle sizes. These results were attributed to the higher tendency of the internal maleic double bonds toward intramolecular cyclization reactions. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6544–6557, 2006

Structure, Solution Aggregation and UV Curing of Hyperbranched Poly(ester-amine)s with Terminal Acrylate Groups

A series of hyperbranched poly(ester-amine)s (defined as HPEA-1–HPEA-5) with terminal acrylate groups were synthesized through Michael addition between piperazine (A2) and trimethylolpropanetriacrylate (TMPTA) (B3) under molar ratios ranged from 1/2 to 1/1.08. As increasing the molar ratio between piperazine and TMPTA, the degree of branching (DB), number average molecular weight (Mn), polydispersity index (Mw/Mn) and glass transition temperature (Tg) of the polymers increased accordingly. Due to their amphiphilic flexible structures, the polymers could form stable aggregates in acetone–acidic water selective solution at volume ratio of 1/25. The influences of polymer structures and the solution pH on the size and size distribution of the aggregates were measured by dynamic light scattering (DLS). The results indicated that smaller size was obtained for the polymer with higher Mn, while the size distribution changed in accordance with Mw/Mn. At lower solution pH, both smaller size and narrower size distribution were obtained. Furthermore, the polymer dispersions were irradiated by UV light to initiate polymerization of acrylate groups within the aggregates. The resulting cured particles possessed decreased size compared with the size of the corresponding aggregates as determined by DLS and transmission electron microscopy (TEM).

An Easy Entry into Schiff Base Molecules Bearing a Pendant Primary Alcohol Function for Hydrogen Bonding

A series of mono-oxidized pyridine, bipyridine, terpyridine and pyridine/pyridazine frameworks were prepared using MnO 2 as oxidant. Corresponding Schiff bases were prepared with aromatic or aliphatic amines carrying various functions such as paraffin chains, terminal acrylates and a second nitrogen atom. Various flexible tethers have been used for the ditopic ligands synthesis. These ligands formed dinuclear helicates for the shorter chains. The dinuclear copper(I) complex prepared from the CH 2 -CH 2 bridge is aggregated in the solid state by a hydrogen bonded network of the residual primary alcohol groups. For the longer spacers the ditopic ligand wraps around a single copper(I) centre forming a mononuclear complex. A significant merit of this work is that it allows the preparation of ligands and complexes retaining the hydroxymethyl function, which are likely to help to stabilize multidimensional networks in the solid state.

Gel polymer electrolyte nanocomposites PEGDA with Mg–Al layered double hydroxides

Polymer electrolyte nanocomposite films composed of PEGDA/LiCF 3SO 3 with various wt.% Mg–Al LDH-2 fillers were prepared. Gel structure was obtained by thermal crosslinking reaction of residual terminal acrylate groups of PEGDA. The molecular weight of PEGDA was ca. 258, 575, and 700, respectively. The ionic conductivity and mechanical properties of resulting nanocomposites were characterized by impedance measurements, X-ray diffraction, and tensile measurement, respectively. The ionic conductivity was highly enhanced in the nanocomposite systems, which is also increased with increasing molecular weight of PEGDA. It was observed in XRD spectra that the layered structure of Mg–Al LDH-2 was totally exfoliated by the prepolymer. In the case of the composite films having 4.5 wt.% of the Mg–Al LDH-2, the ionic conductivity reached to 1.6 × 10 −3 S/cm at room temperature. The incorporation of nanoparticle into the gel resulted in the increase in the tensile modulus by two to three times.

Anionic Polymerization of Acrylates. Synthesis of (Meth)acrylate Di- and Triblock Copolymers Using the Li Ester−Enolate/tert-Alkoxide Initiating System

Methacrylate di- and triblock copolymers composed of methyl (MMA), butyl (BuMA), 2-(dimethylamino)ethyl (DMAMA), and 2-ethylhexyl (EtHMA) methacrylates and tert-butyl acrylate (t-BuA) blocks were prepared by ligated anionic polymerization and characterized by SEC and NMR. The process was initiated with the system methyl 2-lithioisobutyrate/lithium tert-butoxide (MIB-Li/t-BuOLi) at the 1/10 mole ratio, which was recently described as the optimum composition, at THF at -60 °C. The monomers were added to the reaction mixture successively after chosen polymerization intervals and products of the individual polymerization steps were isolated and analyzed. Molecular weights of methacrylate copolymers increased with increasing total amount of the monomers added, and the products of the two-or three-step polymerizations were not detectably contaminated with the products of the foregoing steps, so that the corresponding MWD curves were unimodal and symmetric. The product of MAIA/t-BuA block copolymerization exhibited bimodal MWD, originating probably by the self-termination proceeding at the beginning of the second polymerization step after addition of an acrylate monomer to the living polymethacrylate. A possible mechanism of self-termination and reactions of polymethacrylate chains bearing a few terminal acrylate units are briefly discussed.

Polymerizable liquid crystalline twin molecules: synthesis and thermotropic properties

The synthesis of 14 novel low molar mass liquid crystalline twin molecules is described and experimental details are given. The twin monomers contain two mesogenic units which are connected by a flexible spacer. Two terminal acrylate groups make these twins suitable for photopolymerization. The insertion of lateral groups into the mesogen leads to glassforming properties. We tested several substituents (-OCH3, -CH3) in different positions of the mesogenic unit and investigated their thermotropic properties as well as their crystallization behaviour by polarizing microscopy and DSC experiments. Some of the novel twin molecules with lateral substituents in the mesogenic core have unusually broad mesophases of about 150oC. Below T g stable LC glasses are formed. At room temperature a slow, kinetically hindered crystallization starts after about three hours. The broad mesophases of the twin molecules allow investigations of the photopolymerization kinetics over a wide temperature range. The addition of chiral non-liquid crystalline comonomers and subsequent photopolymerization leads to cholesteric networks with interesting optical properties. Last but not least, the twins are suitable mixing agents which suppress the crystallization of classical mono-rods.

Surfactant-free emulsions for waterborne, two-component polyurethane coatings

Catalytic chain transfer polymerisation based on cobalt II or III chelates is a free radical technique which allows the synthesis of functional oligomers with a terminal α-substituted acrylate group. This paper will review the applications of such oligomers in the design of low molecular weight, graft and block copolymer emulsions and dispersions for waterborne, two-component polyurethane paints. Such emulsions and dispersions have a composition and molecular weight control and offer unique properties when compared with binders prepared via conventional techniques.

Synthesis and characterization of liquid crystalline polyacrylates and non-liquid crystalline polypyrroles from bifunctional monomers

Two kinds of polymerizations of liquid-crystalline N-{{W-{4-[4-(11-acryloyloxy)undecanoxybenzoyl]biphenyleneoxy}alkyl}}pyrrole gave a side-chain liquid-crystalline polyacrylate containing pyrrole group and a non-liquid crystalline polypyrrole containing acrylate group. Liquid crystallinity was determined by DSC and optical polarizing microscope measurements. The monomers having hexyl or decyl group as the alkyl group exhibited an undefined smectic, smectic B, and smectic A phases on the heating stage. The radically polymerized polyacrylate derivatives containing the pyrrole group showed smectic A, smectic C, and undefined smectic phases on the cooling stage. On the other hand, soluble N-substituted polypyrrole derivatives containing the terminal acrylate group which were prepared by chemical oxidative polymerization by ferric chloride catalyst did not show liquid crystallinity. Structure analysis of the polypyrroles performed by 1H and 13C-NMR and FT-IR spectroscopies demonstrated that the polymerization occurred at the pyrrole ring. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3877–3887, 1999

Optimization of photopolymerized bioerodible hydrogel properties for adhesion prevention.

The aim of this study was to optimize the properties of a lubricious bioerodible hydrogel barrier for the prevention of postoperative adhesions. Water-soluble macromers based on block copolymers of poly(ethylene glycol) (PEG) and poly(lactic acid) or poly(glycolic acid) with terminal acrylate groups were used, and these macromers were gelled in vivo by exposure to long wavelength ultraviolet light. The precursor was photopolymerized from buffered saline solution while in contact with the tissues. This resulted in the conformal coating of the tissue with an adherent hydrogel film, while forming a nonadhesive barrier at the free surface, on the treated wound site. The hydrogels were evaluated in two animal models of postsurgical adhesions, first in a rat cecum abrasion model and then in a rabbit uterine horn ischemia model. In the rat cecum model, six of seven animals treated with a hydrogel, with glycolide in the precursor as the comonomer, showed no adhesions; untreated animals and animals treated with precursor, but not gelled with light, showed consistent dense adhesions. In the rabbit uterine horn ischemia model, using hydrogels with lactide in the precursor as the comonomer, and PEG of molecular weight from 6,000 to 18,500 Da, adhesions were dramatically reduced, with occurrence in none of seven animals treated with a gel containing PEG 10,000. By contrast, the seven animals in the control group demonstrated a mean of 35% involvement of the horn length in dense, fibrous adhesions. These materials, photopolymerized in vivo in direct contact with the tissues, appear to form an adherent hydrogel barrier that is highly effective in reducing postoperative adhesions in the models used.(ABSTRACT TRUNCATED AT 250 WORDS)

Terminal Hydroxyalkyl Acrylates as Substrates for Baylis-Hillman Reaction

Terminal hydroxyalkyl acrylates couple with aldehydes under the catalytic influence of DABCO producing the desired multifunctional molecules.

Radiation curing of epoxies

The literature on radiation polymerization of epoxy compounds has been reviewed to assess the potential use of radiation for curing these industrially important monomers. Chemical curing of epoxies may proceed by either cationic or anionic mechanisms depending on the nature of the curing agent, but most epoxies polymerize by cationic mechanisms under the influence of high-energy radiation. Radiation-induced cationic polymerization of epoxy compounds is inhibited by trace quantities of water because of proton transfer from the chain-propagating epoxy cation to water. Several different methods with potential for obtaining high molecular weight polymers by curing epoxies with high-energy radiation have been studied. Polymeric products with epoxy-like properties have been produced by radiation curing of epoxy oligomers with terminal acrylate groups and mixtures of epoxies with vinyl monomers. Both of these types of resin have good potential for industrial-scale curing by radiation treatment.

Structure of oligourethane urea-acrylates

The methods of DTA and X-ray scatter at high and low angles have been used to study the supramolecular structure of segmented oligourethane ureas containing terminal acrylate groups, comparing it with the structure of linear polymers of similar structure. It is shown that high temperature transitions in the thermograms of the oligomers and polymers are in a narrow temperature region. The position of these transitions is essentially determined by the chemical structure of the rigid blocks. It has been established that in oligomeric products as in polymers a domain structure forms. On UV initiated polymerization of the oligomers in the solid state the structural characteristics change only insignificantly.