Acrylate Segments Research Articles

Thermal and Mechanical Analysis of Urethane Acrylate Graft Copolymer Part A: Urethane Macromonomer Base on TDI and EG

Urethane macromonomers (UMs) having different urethane chain lengths (X) were synthesized by the reaction of an isocyanate-terminated prepolymer with 2-hydroxy ethyl methacrylate (HEMA) and isopropanol. The existence and the structural identification of the UMs were verified by FTIR, 1H NMR and 13C NMR spectroscopy. Various percentages of the respective UMs (0-40 wt % acrylate monomers) were then incorporated into methyl methacrylate (MMA) and n-butyl methacrylate (n-BMA) backbones via solution free-radical copolymerization. The resulting methyl methacrylate-g-urethane and n-butyl methacrylate-g-urethane copolymers were characterized by GPC, 1H NMR, 13C NMR, FTIR, TGA and DMA. Phase separation between the urethane segment and the acrylate segment in the graft copolymerization products was investigated by DMA and TEM. DMA results showed that in most graft copolymer products the two respective component parts of PMMA-g-urethane or n-PBMA-g-urethane were compatible as only one Tg was observed. Two glass transitions, at temperatures of 22 and 76 oC, corresponding to the n-PBMA and urethane moieties, were observed when the chain length of the UMs was increased from X=4 to X=32. Microphase separation was also evident in TEM measurement.

Study of the Potential of Amphiphilic Conetworks Based on Poly(2-ethyl-2-oxazoline) as New Platforms for Delivery of Drugs with Limited Solubility

Thermoresponsive amphiphilic conetworks comprising poly(2-ethyl-2-oxazoline) (PEtOx), 2-hydroxyethyl methacrylate, and 2-hydroxypropyl acrylate segments have been studied as new platforms for delivery of drug with limited solubility. Series of conetworks of varied composition were synthesized and swelling kinetics in aqueous media and ethanol were followed. The platforms were loaded with the hydrophobic drug ibuprofen by swelling in its ethanol solution. The structure and properties of the drug carriers were investigated by scanning electron microscopy and differential scanning calorimetry. The release kinetics profiles of ibuprofen from the studied platform were established. The investigation proved the feasibility of the PEtOx-based amphiphilic conetworks as highly effective platforms for sustained ibuprofen delivery.

Biomimetic synthesis of calcium carbonate bilayers interfaced by a diblock copolymer template

Abstract The synthesis of a new class of hybrid materials with two differently oriented layers of calcite at adjacent sides of an organic template is demonstrated. A Langmuir monolayer of the amphiphilic block copolymer poly(butyl acrylate)-b-poly(hydroxypropyl acrylate) directs the formation of a first CaCO3 phase through interaction with the hydrophilic poly(hydroxypropyl acrylate) blocks. After partial hydrolysis of the hydrophobic poly(butyl acrylate) segments a second CaCO3 phase is formed on the monolayer associated to the first mineral phase. Thus, bilayered CaCO3-based hybrid materials are obtained with two differently oriented calcite phases at opposite sides of the polymer film. By using DNA as an additive the crystal orientation in the second layer can be modified.

AB, BAB and (AB)3 poly(ε-caprolactone)-based block copolymers with functionalized poly(meth)acrylate segments

Linear and star-shaped poly(ε-caprolactone) (PCL) block copolymers containing poly(meth)acrylate segments with glycidyl, 2-(trimethylsilyloxy)ethyl and tert-butyl pendant groups were synthesized using mono-, di- and trifunctional PCL macroinitiators and appropriate (meth)acrylate monomers by controlled radical polymerization. The well-defined structures with narrow molecular weight distributions indicate the coexistence of semi-crystalline PCL and amorphous poly(meth)acrylic phases. The hydrophobic nature of the block copolymers can be easily converted to amphiphilic, which with biodegradable and biocompatible PCL segments are promising as polymeric carriers in drug delivery systems. © 2012 Society of Chemical Industry

Synthesis and characterization of particles consisting of a biodegradable poly(l-lactide) core and a functional hydrophilic shell

Block copolymers consisting of poly(solketal acrylate) and poly(l-lactide) were synthesized by combination of atom transfer radical polymerization (ATRP) and ring opening polymerization (ROP) technique. Block copolymerization has been done by two different pathways, simultaneously and sequentially by using a dual functional initiator. Well defined block copolymers were obtained by sequential block copolymerization first implementing ROP of l-lactide followed by ATRP of solketal acrylate. After hydrolysis of the solketal acrylate segments hydrophilic poly(2,3-dihydroxypropyl acrylate) blocks were obtained. The amphiphilic block copolymers were able to self-organize in aqueous solution. Aggregation behavior was studied by means of dynamic and static light scattering. Time dependent enzymatic and hydrolytic degradation of the poly(l-lactide) cores was detected by dynamic light scattering. If enzymatic solutions were used the degradation process proceeded faster and was completed within 4000 min.

Mechanisms ofn-butanol formation in butyl acrylate latexes

The mechanisms involved in the formation of n-butanol during the synthesis of butyl acrylate containing latices were investigated. The experimental results showed that neither the hydrolysis of butyl acrylate nor of the ester bond in the butyl acrylate segments of the polymer played a major role in the formation of n-butanol, which was mainly generated from the polymer backbone, by transfer reactions to polymer chain followed by cyclization.

Dynamic-mechanical behavior of hydrophobic–hydrophilic interpenetrating copolymer networks

Sequential interpenetrating polymer networks (IPNs) were prepared by free-radical polymerization. One of the components of the IPN was a poly(butyl acrylate) (PBA) network, and the other one was a poly(methyl methacrylate-co-hydroxyethyl methacrylate) copolymer network. Dynamic-mechanical experiments show that the IPNs are phase separated: two main α relaxations occur in all samples, the low temperature one corresponding to the PBA network and that appearing at higher temperature due to the copolymer network. The latter shows a shape analogous to a pure poly(hydroxyethyl methacrylate) (PHEMA) network independently of the copolymer composition. The influence of water absorption on the dynamic-mechanical spectrum shows that only a small amount of water reaches the butyl acrylate segments. The dependence of the mechanical behavior of the poly(methyl methacrylate-co-hydroxyethyl methacrylate) copolymer networks with the copolymer composition has been also analyzed. POLYM. ENG. SCI., 46:930–937, 2006. © 2006 Society of Plastics Engineers

Rheological properties of methacrylic acid/ethyl acrylate co-polymer: comparison between an unmodified and hydrophobically modified system

Earlier experimental studies on the emulsion polymerized methacrylic acid/ethyl acrylate co-polymer indicated that the ethyl acrylate (EA) segments are sufficiently blocky to induce hydrophobic association between the EA blocks once the methacrylic acid groups are neutralized by a base. Detailed rheological characterization on semi-dilute solutions suggests that the viscoelastic property is caused by the transient network assembled through hydrophobic associations, rather than by physical chain entanglements. In the semi-dilute solution regime, the hydrophobically modified associative polymer exhibits higher viscosities when compared to the unmodified analogue. This is due to the formation of higher proportion of intermolecular association between the polymer clusters, which enhances the hydrophobic interaction between the hydrophobic macromonomers of different polymer chains. A mechanistic model is proposed to describe the nature of associations between the blocky EA and the hydrophobic segments of the polymer.

`Link-functionalized' and triblock polymer architectures through bifunctional organolanthanide initiators: A review

Bimetallic complexes of the type Cp ∗ 2 Sm-R-Sm Cp ∗ 2 (Cp *=C 5Me 5) were used for the living bisinitiated polymerization of methyl methacrylate and ε-caprolactone, giving polymers with discrete functionalities at the center of the backbone (`link-functionalized'). A method was also developed for generating a bifunctional Sm(III) initiator in situ from a (meth)acrylate monomer and a divalent Cp ∗ 2 Sm precursor. Well-defined, syndiotactic ABA triblock copolymers containing both methacrylate and acrylate segments were prepared in 2 monomer addition steps with this methodology.

ChemInform Abstract: Bimetallic Samarium(III) Catalysts via Electron Transfer Initiation: The Facile Synthesis of Well‐Defined (Meth)acrylate Triblock Copolymers

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Segmental Orientation in Ionically Cross-Linked Blends of Polystyrene and Poly(ethyl acrylate)

Ionically complexed blends are potentially useful model compounds for studying selected aspects of segmental orientation behavior in blends. This paper presents a study of orientation behavior in stoichiometric blends of poly[styrene-co-(styrenesulfonic acid)] and poly[ethyl acrylate-co-(4-vinyl pyridine)] (heteroblends), where ionic cross-links are produced by proton transfer from the acid to the pyridine moieties, thus leading to an effective ionic network whose density is controlled by the counit content of the blend components. Orientation measurements were obtained by infrared dichroism. For blends composed of components with similar counit contents (symmetric blends), the segmental orientation of both the polystyrene and poly(ethyl acrylate) segments increases with ion content when compared at the same relative temperature, a direct result of the effective ionic cross-links. The polystyrene orientation is, however, significantly lower than that in previously-studied ionomer blends based solely on polystyrene (homoblends). This suggests that the orientation of the polystyrene segments in the heteroblends is reduced by a plasticization effect from the poly(ethyl acrylate) segments, attributed to relaxation coupling between the dissimilar chains during stretching. In an asymmetric blend of a sulfonated polystyrene copolymer of low acid content and a poly(ethyl acrylate) copolymer of high pyridine content, the orientation of the styrene segments is much higher than that in the symmetric blend of the same acid content. It is concluded that relaxation coupling is not present in the asymmetric blend, attributed to the high orientation of the ethyl acrylate segments and to the lower ethyl acrylate content.

Bimetallic samarium(III) catalysts via electron transfer initiation: The facile synthesis of well-defined (meth)acrylate triblock copolymers

A method for generating a bifunctional organolanthanide(III) initiator in situ from a (meth)acrylate monomer and a divalent samarium precursor, (C 5Me 5) 2Sm ( 1) or (C 5Me 5) 2Sm(THF) 2 ( 2), is described. This process involves one-electron transfer from the Sm(II) species to monomer, forming radical anions which couple to give a bimetallic samarium(III) enolate that acts as a bisinitiator for living polymerization. Well-defined, highly syndiotactic ABA triblock copolymers containing both methacrylate and acrylate segments were prepared in two monomer addition steps with this methodology. Selective side chain deprotection may be carried out on copolymers containing poly( tert-butyl acrylate) or poly(benzyl methacrylate) blocks to give syndiotactic ester-acid copolymers.

Properties of UV‐curable polyurethane acrylates: Effect of reactive diluent

AbstractSeveral families of UV‐cured polyurethane acrylates were synthesized, and the effects of reactive diluent type and content on their physical properties were investigated. Increasing reactive diluent content promoted the development of a second, high glass transition temperature phase in all the materials, thereby leading to increased strength and modulus. Changes in the extensibility of the samples upon addition of reactive diluent were inversely related to the effect of the diluent on the crosslink density. The effects of using different reactive diluents (di‐, tri‐, and tetraethylene glycol diacrylate and N‐vinyl pyrrolidone) on the physical properties of the samples were attributed to differences in the softening point (Tg) of the homopolymer reactive diluents and the relative compatibility of the reactive diluents with the urethane acrylate segments.