Presence Of Oligo Research Articles

Properties of PLA-co-PBSu Copolymers Rapidly Synthesized by Reactive Processing

This work describes the synthesis of poly(lactic acid) by the ring-opening polymerization of L-lactide in the presence of oligo(butylene succinate) with two different molecular weights (Mn = 6100 and 16300 g/mol) as a macroinitiator during reactive processing. The macroinitiators were added in concentrations 1 wt%, 2.5 wt%, 5 wt%, 10 wt% and 15 wt% in respect to the L-lactide mass in the premix. The properties of the received copolymers were extensively studied with spectroscopic techniques, GPC, DSC, XRD, TGA as well as nanoindentation. Blocky copolymers were received with number average molecular weights ranging from 30 to 100 kg/mol, which decreased with increasing the PBSu content in the feed. The introduction of the flexible PBSu chains decreased the single glass transition detected, while DSC and XRD gave indications that both components crystallized in the copolymers with PBSu premix content > 5 wt%. Thermal stability was maintained and depended on the composition and molecular weight. Nanoindentation showed that despite the decreasing trend of hardness and elastic modulus with increasing PBSu content, the PLA-PBSu 2.5% copolymers had simultaneously higher elasticity modulus and strength compared to the other compositions, possibly because of a complementary effect of their high molecular weight and crystallinity. These copolymers were promising for production with continuous reactive extrusion, a novel, fast and economically viable method to commercially produce PLA-based polymers.

Role of oligo(malic acid) on the formation of unilamellar vesicles

Stable unilamellar dipalmitoylphosphatidylcholine vesicles were produced by using oligo(malic acid) and cholesterol. Detailed physico-chemical characterization prove that by using oligo(malic acid) the substitution of PEGylated lipids for sterically stabilization comes possible. The polymer molecules cover the outer surface of spherical-shaped vesicles, and an asymmetrical composition occurs in the two leaflets of the phospholipid bilayer. The oligo(malic-acid) and cholesterol are enriched in the outer side assuring the stabilization of vesicles. Cholesterol plays an important role in the self-assembly of components as it makes the entering of oligomers possible deep into the polar head-region of lipids. The presence of oligo(malic acid) molecules does not induce degradation by hydrolysis of lipid molecules but the vesicle system turns into a sensitive form giving a possibility for pH sensitive targeting. Preliminary investigation on the investigated oligo(malic acid)-stabilized vesicles do not show any toxic effect promising their applicability in the field of liposomal drug delivery.

The Phenotypes of Polycystic Ovary Syndrome Defined by the 1990 Diagnostic Criteria Are Associated with Higher Serum Vaspin Levels than the Phenotypes Introduced by the 2003 Criteria

Objective: Patients with polycystic ovary syndrome (PCOS) diagnosed with the 1990 criteria (i.e. presence of oligo- and/or anovulation (ANOV) and hyperandrogenemia and/or hyperandrogenism (HA) with or without polycystic ovaries (PCO)) appear to have a more adverse metabolic profile than patients diagnosed with the additional criteria introduced in 2003 (i.e. presence of HA and PCO without ANOV and presence of ANOV and PCO without HA). Vaspin is a novel adipokine that appears to preserve insulin sensitivity. We aimed to assess serum vaspin levels in patients with different PCOS phenotypes. Methods: We studied 100 patients with PCOS diagnosed with the 1990 criteria (group I), 100 patients with PCOS diagnosed with the additional 2003 criteria (group II) and 50 healthy controls. Results: Serum vaspin levels were higher in groups I and II than in controls (p < 0.001 and p = 0.001, respectively) and in group I when compared to group II (p = 0.045). In patients with PCOS, serum vaspin levels were independently correlated with BMI (p < 0.001) and the homeostasis model assessment of insulin resistance (HOMA-IR) (p = 0.002). Conclusions: PCOS is associated with elevated serum vaspin levels. This increase might represent a compensatory mechanism to preserve insulin sensitivity. Moreover, serum vaspin levels reflect the severity of PCOS and are significantly increased in its ‘classical’ phenotypes.

The prevalence and clinical features of polycystic ovary syndrome in a Moscow population

The objective of the present study was to estimate the prevalence and and characterize clinical phenotypes of PCOS. A total of 312 women from 18 to 45 years of age working engaged in Moscow enterprises were examined in 2009. All of them were interviewed by questionnaire, underwent routine medical examination, anthropometry and blood sampling for the measurement of Prl, TSH, FSH, testosterone, 17-OP, and DHEAS levels. The degree of hirsutism was assessed using the modified Ferriman-Galway scale. Women with fewer than eight cycles during a year were regarded as having menstrual problems. All women presenting with disturbances were invited for verification of the diagnosis. PCOS was diagnosed based on the Rotterdam (2003) criteria (the presence of oligo-/amenorrhea and clinically manifest hyperandrogenism (hirsutism), with all other disorders simulating the clinical picture of PCOS being excluded). All patients with clinical signs of PCOS were examined at the Endocrinological Research Centre. They were divided into the following groups: 1. Regular menstrual cycles in the absence of hirsutism. 2. Menstrual dysfunction (oligo-/amenorrhea) without hirsutism. 3. Hirsutism without menstrual disturbances. 4. Menstrual dysfunction plus hirsutism. Mean age of the women was 30,2±7,4 years, their BMI 24±5,5, overweight patients comprised 17,3% of the total (n=54), obesity occurred in 14.7% (n=46), oligoamenorrhea in 12.8%, hirsutism in 9.3%, acne in 6.4%, infertility in 2.6%, obesity in 14%. Menstrual dysfunction without hirsutism was documented in 17/312 (5.4%) cases. The prevalence of PCOS in this phenotypical group was estimated at 17.6%. Hirsutism in the absence of menstrual dysfunction was diagnosed in 8/312 (2.6%) women (prevalence of PCOS 62.5%), menstrual dysfunction plus hirsutism in 21/312 (6.7%) patients (prevalence of PCOS 85.7%). The study has demonstrated that the overall prevalence PCOS in the given population was 6,4%, but individual symptoms of this condition were manifest much more frequently than that. It is concluded that the diagnosis of PCOS is most reliably confirmed by the presence of combination of oligo-/amenorrhea and hirsutism.

Bax expression remains unchanged following antisense treatment directed against BCL-2

Antisense oligonucleotides (oligos) have been evaluated in both in vivo and in vitro prostate cancer models. Although most contain a single mRNA binding site, our laboratory has also evaluated bispecific types directed toward two proteins. This study evaluates the inhibition of in vitro propagating LNCaP cells employing mono- and bispecific oligos directed against bcl-2 [the second binding site was directed against the epidermal growth factor receptor (EGFR)]. Employing RT-PCR, the expression of two apoptosis regulating proteins, bcl-2 and non-targeted bax, was then evaluated. LNCaP prostate tumor cells were initially incubated for 24 h in the presence of oligos (6.25 μM) directed against bcl-2 and compared to lipofectin containing controls. Comparable and significant growth inhibition was produced by both mono- and bispecific forms. Employing RT-PCR to determine the expression of bcl-2, we found that the greatest amount of mRNA suppression approached 100% for each oligo type: monospecific MR4 (directed only against bcl-2), 100%; and bispecifics MR24 and MR42, 86 and 100%, respectively. We conclude, based upon both inhibition of in vitro growth and bcl-2 expression, that bispecific antisense oligos directed against EGFR and bcl-2 mRNAs are at least as effective as a monospecific directed solely toward bcl-2. In an effort to determine a compensatory response by cells evading apoptosis in the presence of bcl-2 suppression, the levels of mRNA encoding the non-targeted apoptosis activating protein bax were evaluated. Non-targeted protein suppression by these bispecifics has previously been demonstrated against prostate-specific membrane antigen (PSMA). However, in contrast to effects against bcl-2 and PSMA, no significant alteration in bax expression was produced by either oligo type. In LNCaP cells, bcl-2 suppression does not influence bax expression and, at least for this protein, there is no compensatory change in bax expression regulating apoptosis at this level. Identifying changes in the expression of proteins which regulate apoptosis is important if gene therapy targets bcl-2.

Dexras1 Interacts with FE65 to Regulate FE65-Amyloid Precursor Protein-dependent Transcription

FE65 is an adaptor protein that binds to and forms a transcriptionally active complex with the gamma-secretase-derived amyloid precursor protein (APP) intracellular domain. The regulatory mechanisms of FE65-APP-mediated transcription are still not clear. In this report, we demonstrate that Dexras1, a Ras family small G protein, binds to FE65 PTB2 domain and potently suppresses the FE65-APP-mediated transcription. The suppression is not via competition for binding of FE65 between Dexras1 and APP because the two proteins can simultaneously bind to the FE65 PTB2 domain. Phosphorylation of FE65 tyrosine 547 within the PTB2 domain has been shown to enhance FE65-APP-mediated transcription but not to influence binding to APP. Here we find that this phosphorylation event reduces the binding between Dexras1 and FE65. We also demonstrate that Dexras1 inhibits the FE65-APP-mediated transcription of glycogen synthase kinase 3beta (GSK3 beta). Moreover, small interfering RNA knockdown of Dexras1 enhances GSK3 beta expression and increases phosphorylation of Tau, a GSK3 beta substrate. Thus, Dexras1 functions as a suppressor of FE65-APP-mediated transcription, and FE65 tyrosine 547 phosphorylation enhances FE65-APP-mediated transcription, at least in part, by modulating the interaction between FE65 and Dexras1. These findings reveal a novel regulatory mechanism for FE65-APP-mediated signaling.

Regulation of Estrogen Receptor-mediated Long Range Transcription via Evolutionarily Conserved Distal Response Elements

Nuclear signaling by estrogens rapidly induces the global recruitment of estrogen receptors (ERs) to thousands of highly specific locations in the genome. Here, we have examined whether ER binding sites that are located distal from the transcription start sites of estrogen target genes are functionally relevant. Similar to ER binding sites near the proximal promoter region, ER binding sites located at distal locations are occupied by ERs after estrogen stimulation. And, like proximal bound ERs, ERs occupied at distal sites can recruit coactivators and the RNA polymerase transcription machinery and mediate specific structural changes to chromatin. Furthermore, ERs occupied at the distal sites are capable of communicating with ERs bound at the promoter region, possibly via long range chromosome looping. In functional analysis, disruption of the response elements in the distal ER binding sites abrogated ER binding and significantly reduced transcriptional response. Finally, sequence comparison of the response elements at the distal sites suggests a high level of conservation across different species. Together, our data indicate that distal ER binding sites are bona fide transcriptional enhancers that are involved in long range chromosomal interaction, transcription complex formation, and distinct structural modifications of chromatin across large genomic spans.

Surface polyethylene glycol enhances substrate-mediated gene delivery by nonspecifically immobilized complexes

Substrate-mediated gene delivery describes the immobilization of gene therapy vectors to a biomaterial, which enhances gene transfer by exposing adhered cells to elevated DNA concentrations within the local microenvironment. Surface chemistry has been shown to affect transfection by nonspecifically immobilized complexes using self-assembled monolayers (SAMs) of alkanethiols on gold. In this report, SAMs were again used to provide a controlled surface to investigate whether the presence of oligo(ethylene glycol) (EG) groups in a SAM could affect complex morphology and enhance transfection. EG groups were included at percentages that did not affect cell adhesion. Nonspecific complex immobilization to SAMs containing combinations of EG- and carboxylic acid-terminated alkanethiols resulted in substantially greater transfection than surfaces containing no EG groups or SAMs composed of EG groups combined with other functional groups. Enhancement in transfection levels could not be attributed to complex binding densities or release profiles. Atomic force microscopy imaging of immobilized complexes revealed that EG groups within SAMs affected complex size and appearance and could indicate the ability of these surfaces to preserve complex morphology upon binding. The ability to control the morphology of the immobilized complexes and influence transfection levels through surface chemistry could be translated to scaffolds for gene delivery in tissue engineering and diagnostic applications.

Surface passivation using oligo(ethylene glycol) in ATRP-assisted DNA detection

Abstract We recently reported a DNA sensing method using polymerization to amplify signal outputs [X. Lou, M.S. Lewis, C.B. Gorman, L. He, Anal. Chem. 77 (2005) 4698–4705]. In the current report an optimization of sensor surface chemistry is conducted in which (S–CH2CH2–OEG6–OMe)2 is used as the preferred surface passivation agent to reduce nonspecific adsorption experienced during ATRP-assisted DNA detection. The presence of oligo(ethylene glycol) (OEG) moieties on the sensor surface significantly reduces background adsorption of proteins, polymers, and reaction monomers used during DNA detection. The level of reduction in background nonspecific adsorption closely depends on the incubation solvent and the incubation time used, as evidenced by the ellipsometric and surface plasmon resonance (SPR) results. Reflectance FTIR results suggest that the surfaces with moderately ordered SAMs exhibit better protein resistance, consistent to the previous observations. Subsequent DNA binding experiments show no apparent decrease in DNA hybridization and ligation efficiencies when OEGylated self-assembled monolayers are used as the passivation layer. Improved DNA detection sensitivity is achieved from reduced background noises.

Prevalence and Risk Factors of Atherosclerosis in Patients with Psoriatic Arthritis

To evaluate the extent of subclinical atherosclerosis by measuring the intima-media wall thickness (IMT) of the common carotid artery in patients with psoriatic arthritis (PsA) and to identify vascular risk factors associated with PsA. Forty-seven patients with PsA were compared with 100 allegedly healthy subjects. Carotid duplex scanning was used to measure common carotid artery IMT. Traditional risk factors, such as gender, age, body mass index (BMI), hypertension, smoking, and lipids were checked. Assessment of PsA activity included clinical patterns of involvement, degree of severity, duration of morning stiffness, number of tender and swollen joints, degree of pain and fatigue, the Bath Ankylosing Spondylitis Disease Activity Index, the Psoriasis Area and Severity Index, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and fibrinogen. The average IMT (mean +/- standard deviation) for PsA patients was significantly higher compared with controls (0.76 +/- 0.11 versus 0.64 +/- 0.27, respectively, P < 0.00001) for the whole group and after adjustment for age, gender, BMI, hypertension, and hyperlipidemia. The PsA subjects had significantly higher levels of hypertension, hyperlipidemia, ESR, CRP, and fibrinogen, and their average IMT significantly correlated with age, BMI, duration of skin and joint disease, spine involvement, ESR, and fibrinogen. IMT did not correlate with the presence of oligo- or polyarthritis but was increased in patients with clinical spinal involvement. IMT was not associated with the degree of severity or the use of different therapies for PsA, including methotrexate or tumor necrosis factor-alpha-blocking agents. PsA patients exhibited greater IMT than healthy controls. Increased IMT independently correlated with parameters of disease activity and conventional risk factors of atherosclerosis.

Leptin Increases Axonal Growth Cone Size in Developing Mouse Cortical Neurons by Convergent Signals Inactivating Glycogen Synthase Kinase-3β

We examined the effects of the adipose hormone leptin on the development of mouse cortical neurons. Treatment of neonatal and adult mice with intraperitoneal leptin (5 mg/kg) induced extracellular signal-regulated kinase (ERK) 1/2 phosphorylation in pyriform and entorhinal cortex neurons. Stimulation of cultured embryonic cortical neurons with leptin evoked Janus kinase 2 and ERK1/2 phosphorylation and activated the downstream effector 90-kDa ribosomal protein S6 kinase. Moreover, leptin elicited the phosphorylation of the phosphatidylinositol 3-kinase effector Akt and evoked Ser-9 phosphorylation of glycogen synthase kinase-3beta (GSK3beta), an event inactivating this kinase. Leptin-mediated GSK3beta phosphorylation was prevented by the MEK/ERK inhibitor PD98059, the phosphatidylinositol 3-kinase inhibitor LY294002, or the protein kinase C inhibitor GF109203X. Exposure of cortical neurons to leptin also induced Ser-41 phosphorylation of the neuronal growth-associated protein GAP-43, an effect prevented by LY294002 and GF109203X but not by PD98059. Ser-41-GAP-43 phosphorylation is usually high in expanding axonal growth cones. Neurons exposed to 100 ng/ml leptin for 72 h displayed reduced rate of growth cone collapse, a shift of growth cone size distribution toward higher values, and a 4-fold increase in mean growth cone surface area compared with control cultures. The leptin-induced growth cone spreading was hampered in cortical neurons from Lepr(db/db) mice lacking functional leptin receptors; it was associated with localized Ser-9-GSK3beta phosphorylation and mimicked by the GSK3beta inhibitor SB216763. At concentrations preventing GSK3beta phosphorylation, PD98059, LY294002, or GF109203X reversed the leptin-induced growth cone surface enlargement. We concluded that the leptin-mediated regulation of growth cone morphogenesis in cortical neurons relies on upstream regulators of GSK3beta activity.

Photoreaction of [Ru(hat)2phen]2+ with Guanosine‐5′‐Monophosphate and DNA: Formation of New Types of Photoadducts

[Ru(hat)2phen]2+ (HAT=1,4,5,8,9,12-hexaazatriphenylene, phen=1,10-phenanthroline) interacts with a good affinity with polynucleotides and DNA by intercalation, despite the presence of a second voluminous ancillary HAT ligand. It photoreacts with guanosine-5'-monophosphate (GMP). From HPLC, ESMS and NMR analyses, it can be concluded that this complex forms photoadducts with GMP. In contrast to the photoadducts isolated with Ru-TAP complexes (TAP=1,4,5,8-tetraazaphenanthrene), the photoadducts with [Ru(hat)2phen]2+ contain a covalent link between the oxygen atom of the guanine unit and a HAT ligand. Formation of oxidised photoadducts and compounds resulting from the addition of two GMP entities to the complex are also detected as side products. In the presence of oligo- and polynucleotides, [Ru(hat)2phen]2+ yields photoadducts when guanine bases are present.

Evidence for polyadenylated mRNA in Pseudomonas aeruginosa.

In this paper, we report the synthesis of Pseudomonas aeruginosa cDNA in the presence of oligo(dT) primers. Hybridization of oligonucleotide DNA microarrays indicates that under the experimental conditions used, at least 43.7% of the expressed genes from P. aeruginosa PAO1, representing many different functional classes, can be detected by using oligo(dT)-primed cDNAs.

Inclusion of Poly(ethylene glycol)s by Crystalline (R)-(1-Naphthyl)glycyl-(R)-phenylglycine

Crystallization of (R)-(1-naphthyl)glycyl-(R)-phenyl-glycine [(R,R)-1] in the presence of oligo(ethylene glycol) dimethyl ethers 2(n) or poly(ethylene glycol)s (PEGs, 3(Mn )) afforded inclusion compounds. The ratio of (R,R)-1/the guest polymer (2 or 3) was proportional to the length of the polymer chain. The crystal structure of a hepta(ethylene glycol) dimethyl ether-included compound was disclosed by X-ray crystallography which showed that (R,R)-1 molecules form a sheet and the guest molecule penetrates the crystal lattice of (R,R)-1 through a one-dimensional channel on the sheet. Powder X-ray analysis revealed that, regardless of the length of the guest polymer, the distance between the neighboring sheets remains unchanged (12.0–12.3 Å) in these inclusion crystals. By thermal analysis, it was shown that the decomposition points of these inclusion compounds became higher with the longer PEG included. The inclusion phenomenon enabled the fractionation of PEGs with various molecular weights, among which longer PEG was preferably included.

Nonionic hydrogels by copolymerization of vinylene carbonate and oligo(ethylene glycol) vinyl ethers

Bulk polymerization of vinylene carbonate (VCA) with ethylene glycol monovinyl ether (EMVE), diethylene glycol monovinyl ether (DMVE) and methyl triethylene glycol vinyl ether (MTVE), respectively, was carried out. Compared with DMVE and MTVE, the yield of the VCA copolymer with EMVE was low due to a side reaction of acetalization. The copolymerization of MTVE with VCA has been shown to produce linear copolymers and alternating copolymers have been found to form at a 1:1 molar monomer ratio. The copolymerization of EMVE and DMVE with VCA, on the other hand, generally yielded crosslinked copolymers. The reason may be a radical transfer reaction that occurred at methylene groups adjacent to hydroxyl groups of pendent oxyethylene moieties, as inferred from studying the swelling behavior of hydrolyzed copolymers in acidic aqueous solution. The copolymers and their hydrolysis products, especially copoly(MTVE/VCA) and copoly(DMVE/VCA), exhibited low glass transition temperatures, which is apparently due to flexible pendent groups on polymer chains. The copolymerization in the presence of oligo(ethylene glycol) divinyl ethers as crosslinking agents followed by hydrolysis with a 5wt.% NaOH solution gave rise to the formation of three different nonionic hydrogels. The swelling behavior of all the gels was found to be independent of the presence of some electrolyte salts at various concentrations in an aqueous solution. However, the hydrogels based on copoly(EMVE/VCA) and copoly(DMVE/VCA) were shown to be unstable under acidic conditions, whereas those based on copoly(MTVE/VCA) were found to be only slightly influenced by the pH value of an aqueous medium.

Polymerization of styrene in the presence of oligo(ethylene glycol) alkoxides: a new route to amphiphilic polymers?

Polymerization of styrene occurs at ambient temperature in the presence of H(OCH2CH2)nO−, K+, where n=1–5. The reaction rate and molecular weight of polymer can be controlled by the number of ether oxygen atoms in the initiator molecule. These dependencies are related to the presence of aggregates of alkoxide molecules and to the formation of associates of oligo(ethylene oxide) chains with potassium cations. Chain transfer reactions are discussed.

Polyadenylylation in mycobacteria: evidence for oligo(dT)-primed cDNA synthesis

The ability of mRNA to direct synthesis of cDNA in the presence of oligo(dT) was analysed using a novel application of fluorescein-11-dUTP incorporation into cDNA by reverse transcriptase. Evidence is provided for the first time that a majority of the mycobacterial mRNA pool is polyadenylylated. mRNA transcripts of hsp65 were also amplified with specific primers from the oligo(dT)-primed cDNA preparation in Mycobacterium bovis BCG, M. smegmatis and M. vaccae. Furthermore, PCR amplication of cDNAs for genes entD, entC and trpE2 from M. bovis BCG yielded the expected products when reverse transcription was primed with oligo(dT), suggesting that polyadenylylation is a general phenomenon in mycobacteria.

Alternating copolymers for novel polymer electrolytes: the electrochemical properties

Gel electrolyte films were prepared on the basis of alternating copolymers of maleic anhydride (MAN) and oligo(ethylene glycol) 4divinyl ether ((EG) 4DVE) by in situ photopolymerization of the monomers in the presence of oligo(ethylene glycol) 11dimethylether ((EG) 11DME) and LiCF 3SO 3. Additionally, terpolymers of MAN and (EG) 4DVE with butylvinyl ether (BVE) or ethoxytri(ethylene glycol)methacrylate (EtO(EG) 3MA) were used as polymer matrix for gel electrolytes because of their lower network density. All these gel electrolyte films are heterogeneous materials. The ionic association was studied by Raman spectroscopy. The content of free anions and the relative intensity of the LiO 6 breathing mode was found to be comparable to the behavior detected for the corresponding liquid electrolyte. The self-diffusion of charge carriers and plasticizer was studied by PFG-NMR. The results indicate, that this technique mainly records the self-diffusion in the liquid phase of the studied heterogeneous gel electrolyte systems, because a low correlation between conductivity and self diffusivity and a low dependence of the self-diffusivity on the composition of the system were found. Maximum conductivities of 5×10 −5 S cm −1 at room temperature with an Arrhenius type temperature dependence were observed for terpolymer systems with 75 wt% of (EG) 11DME. The cationic transference numbers were higher than 0.5. These gel electrolytes show a higher anodic decomposition voltage and an increased Li plating stripping efficiency compared with gel electrolyte systems on the basis of poly((EG) n DMA).

Properties of gel electrolytes based on crosslinked copolymers of oligo(ethylene glycol) dimethacrylate and cyanomethyl methacrylate

Gel electrolyte films were prepared from oligo(ethylene glycol) dimethacrylate ((EG) n DMA, n=23) and cyanomethyl methacrylate (CyMA) by photoinitiated in situ copolymerization in the presence of oligo(ethylene glycol) dimethylether ((EG) n -DME, n=11) and LiCF 3SO 3. The influence of the content of CyMA in the copolymer on the ionic association of LiCF 3SO 3 as well as on the thermal and electrochemical properties of the gels was studied. About 80 mol% CyMA in the copolymer network causes a relatively high dissociation degree of LiCF 3SO 3 (≈50%), cationic transference numbers t +≈0.5 and an anodic stability up to 5 V. The ionic conductivity σ shows a maximum around 20 mol% CyMA attaining σ≈10 −4 S/cm at ambient temperature. The decrease of σ at higher contents of CyMA in the crosslinked polymer is attributed to the insertion of substantial parts of (EG) 11DME into the copolymer network and to a chain stiffening effect of CyMA.

Ionic Conductivity−Structure Property Relationship in Gel Electrolytes on the Basis of Oligo(ethylene glycol)23 Dimethacrylate Plasticized with Oligo(ethylene glycol)11 Dimethyl Ether

This paper reports dielectric spectroscopic studies completed by electrochemical measurements in combination with DSC and PFG-NMR investigations to study the charge carrier transport in gel electrolytes, which were prepared by photoinitiated polymerization of oligo(ethylene glycol)23 dimethacrylate [(EG)23DMA] in the presence of oligo(ethylene glycol)11dimethyl ether [(EG)11DME] as plasticizer and LiCF3SO3. The resulting films show a glass transition at about −60 °C and the melting of the plasticizer around −12 °C. Below the glass transition two relaxation processes were observed by dielectric spectroscopy, which most likely are to be related to the γ relaxation of the EG groups and the β relaxation of the methacrylate groups. The high-temperature behavior of the dielectric response is dominated by the conductivity, which is weakly dependent on the frequency in this temperature range. The permittivity goes through a maximum at room temperature and decreases with further enhancement of the temperature in c...