71 |
A Mixed Biosensing Film Composed of Oligonucleotides and Poly (2-hydroxyethyl methacrylate) Brushes to Enhance Selectivity for Detection of Single Nucleotide PolymorphismsWong, April Ka Yee 02 September 2010 (has links)
This work has explored the capability of a mixed film composed of oligonucleotides and oligomers to improve the selectivity for the detection of fully complementary oligonucleotide targets in comparison to partially complementary targets which have one and three base-pair mismatched sites. The intention was to introduce a “matrix isolation” effect on oligonucleotide probe molecules by surrounding the probes with oligomers, thereby reducing oligonucleotide-to-oligonucleotide and/or oligonucleotide-to-surface interactions. This resulted in a more homogeneous environment for probes, thereby minimizing the dispersity of energetics associated with formation of double-stranded hybrids. The mixed film was constructed by immobilizing pre-synthesized oligonucleotides onto a mixed aminosilane layer and then growing the oligomer portion by surface-initiated atom transfer radical polymerization (ATRP) of 2-hydroxy methacrylate (PHEMA). The performance of the mixed film was compared to films composed of only oligonucleotides in a series of hybridization and melt curve experiments. Surface characterization techniques were used to confirm the growth of the oligomer portion as well as the presence of both oligonucleotides and oligomer components. Polyatomic bismuth cluster ions as sources for time-of-flight secondary ion mass spectrometry experiments could detect both components of the mixed film at a high sensitivity even though the oligomer portion was at least 200-fold in excess.
At the various ionic strengths investigated, the mixed films were found to increase the selectivity for fully complementary targets over mismatched targets by increasing the sharpness of melt curves and melting temperature differences (delta Tm) by 2- to 3-fold, and by reducing non-specific adsorption. This resulted in improved resolution between the melt curves of fully and partially complementary targets. A fluorescence lifetime investigation of the Cy3 emission demonstrated that Cy3-labeled oligonucleotide probes experienced a more rigid microenvironment in the mixed films.
These experiments demonstrated that a mixed film composed of oligonucleotides and PHEMA can be prepared on silica-based substrates, and that they can improve the selectivity for SNP discrimination compared to conventional oligonucleotide films.
|
72 |
Polymerization And Characterization Of Methylmethacrylate By Atom Transfer Radical PolymerizationAran, Bengi 01 May 2004 (has links) (PDF)
In this work, methylmethacrylate, MMA was polymerized by ATRP method to obtain low molecular weight living polymers. The initiator was p-toluenesulfonylchloride and catalyst ligand complex system were CuCl-4,4&rsquo / dimethyl 2,2&rsquo / bipyridine. Polymers with controlled molecular weight were obtained.
The polymer chains were shown by NMR investigation to be mostly syndiotactic. The molecular weight and molecular weight distribution of some
polymer samples were measured by GPC method. The K and a constants in [h]=K Ma equation were measured as 9.13x10-5 and 0.74, respectively. FT-IR and X-Ray results showed regularity in polymer chains. The molecular weight-Tg relations were verified from results of molecular weight-DSC results.
|
73 |
Preparation And Characterization Of Acrylic Bone CementsEndogan, Tugba 01 September 2005 (has links) (PDF)
Acrylic bone cements are used in dentistry and orthopedic surgery to fix prosthetic devices into the bone. Bone cements transfer and distribute the applied load and increase the load-carrying capacity of the prosthesis/cement/bone system with the help of mechanical bonding between the device and the bone. In spite of all their advantages, bone cements have several drawbacks such as insufficient mechanical properties, high exothermic polymerization temperature, release of monomer to the environmental tissue and loosening of implant. Studies are being carried out to improve bone cement formulations with low curing temperature, good mechanical properties and good biocompatibility. In this study, bone cements with different compositions were prepared by using poly(methyl methacrylate) (PMMA) microspheres, barium sulphate (BaSO4) radiopaque agent, inorganic hydroxyapatite (HA) particles and 1-dodecyl mercaptan (DDM) chain stopping agent. Mechanical and thermal properties of the prepared bone cements were examined. When 8% hydroxyapatite was added into the formulation, both tensile and compressive strengths were increased and curing temperature was decreased. Addition of 13% BaSO4 caused 0.98% and 10.29% decrease in tensile and compressive strength values, respectively. Addition of 1%, 2% and 3% DDM, relative to the amount of methyl methacrylate monomer, decreased the maximum temperature from 101.78° / C to 91.80° / C, 78.38° / C and 71.35° / C, respectively.
All compositions of the prepared bone cements fulfilled the minimum compressive strength (70 MPa) requirement and the minimum curing temperature was obtained as 71.35° / C. In order to have optimum desired properties, further studies to improve biocompatibility, mechanical and thermal properties of bone cements are needed.
|
74 |
Effect of chemical structure and crosslinking density on the thermo-mechanical properties and toughness of (meth)acrylate shape-memory polymer networksSafranski, David L. 31 March 2008 (has links)
The objective of this work is to characterize and understand structure- mechanical property relationships in (meth)acrylate networks. The networks are synthesized from mono-functional (meth)acrylates with systematically varying sidegroup structure and multi-functional crosslinkers with varying mole fraction and functionality. Fundamental trends are established between the network chemical structure, crosslink density, glass transition temperature, rubbery modulus, failure strain, and toughness. The glass transition temperature of the networks ranged from -29 to 112 °C, and the rubbery modulus ranged from 2.8 to 129.5 MPa. At low crosslink density (Er < 10 MPa) network chemistry has a profound effect on network toughness. At high crosslink densities (Er > 10 MPa), network chemistry has little influence on material toughness. The characteristic ratio of the mono-functional (meth)acrylates components is unable to predict trends in thermoset toughness as a function of chemical structure, as is accomplished for thermoplastics. The cohesive energy density is a better tool for prediction of network mechanical properties. Due to superior mechanical properties, networks with phenyl ring sidegroups are further investigated to understand the effect of phenyl ring distance on toughness. This work provides a fundamental basis for designing (meth)acrylate shape memory polymer networks with specific failure strain, toughness, glass transition temperature, and rubbery modulus.
|
75 |
Avaliação in vitro da citotoxicidade de resinas acrílicas para reembasamento baseadas em uma nova formulaçãoCosta, Cristiane Campos [UNESP] 19 March 2009 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:28:55Z (GMT). No. of bitstreams: 0
Previous issue date: 2009-03-19Bitstream added on 2014-06-13T20:58:45Z : No. of bitstreams: 1
costa_cc_me_arafo.pdf: 3083928 bytes, checksum: 2605dd91339dbf0d4e3c26e02afc6696 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O objetivo deste estudo foi determinar a citotoxicidade in vitro de duas resinas reembasadoras experimentais autopolimerizáveis contendo alta concentração de agentes de ligação cruzada, etilenoglicol dimetacrilato (EGDMA) e 1,4-butanodiol dimetacrilato (BDMA) comparadas com uma resina reembasadora comercial (Tokuyama Rebase Fast II). Foram confeccionados corpos-de-prova em forma de discos das três resinas acrílicas reembasadoras rígidas sob condições assépticas. Os fibroblastos (L929) foram cultivados em placas com 96 compartimentos e incubadas por 24 h em meio de cultura Eagle. Os extratos foram preparados, colocando-se três amostras de cada resina em frascos de vidro estéreis com 9 mL de meio de Eagle e incubadas a 37º C por 24 h. O efeito citotóxico dos extratos foram avaliados utilizando os testes de incorporação do 3H-timidina e MTT, que refletem os níveis de síntese de DNA e metabolismo celular, respectivamente. Os dados foram analisados estatisticamente, utilizando análise de variância (P<0.05). Para o teste de incorporação do 3H-timidina, não foram observadas diferenças significativas (P>0.05) entre os materiais. A média da quantidade do isótopo incorporado no DNA celular para todas as resinas acrílicas foi estatisticamente menor do que para o controle. Todas as resinas acrílicas foram classificadas pelo teste de incorporação do 3Htimidina como moderadamente citotóxicas. Da mesma forma, para o teste do MTT, não foi encontrada diferença significativa para a citotoxicidade entre os materiais (P>0.05). Quando a citotoxidade foi comparado com o grupo controle, todas as resinas foram classificadas entre não citotóxicas e discretamente citotóxicas pelo teste do MTT. Assim, conclui-se que a incorporação dos agentes de ligação cruzada, EGDMA e BDMA não influenciaram significativamente sobre a citotoxicidade observada. Não houve diferença... / The aim of this study was to determine the cytotoxicity in vitro of two trials autopolymerizing reline systems made with higher concentration of cross-linking agents, EGDMA and BDMA compared to a commercial reline resin. Sample disks of the three hard reline acrylic resins were fabricated under aseptic conditions. The Fibroblast L929 cells were cultured in 96-well plates and incubated for 24 h in Eagle's medium. Eluates were prepared by placing three samples into a sterile glass vial with 9 mL of Eagle's medium and incubating at 37ºC for 24 h. The cytotoxic effect from the eluates was evaluated using the 3H-thymidine incorporation and MTT assays, which reflect DNA synthesis levels and cell metabolism, respectively. The data were statistically analyzed by using the one-way analysis of variance (P<.05). With the 3H-thymidine incorporation assay, no significant differences (P > .05) were found between the materials. The mean quantity of isotope incorporated into cellular DNA for all acrylic resins was statistically smaller than for the control. All acrylic resins were graded by the 3Hthymidine incorporation assay as moderate cytotoxic. Similarly, with the MTT assay, no significant difference in cytotoxicity was found between the materials (P > .05). When the cytotoxicity was compared with control group, all resins assay were between non cytotoxic and slight cytotoxic by the MTT. The incorporation of cross-linking agents, EGDMA and BDMA had no significant influence on the cytotoxicity observed. There was no cell viability difference between all materials in both assays.
|
76 |
Adição de nanopartículas de prata ao Poli (metil metacrilato): análise microbiológicaTakamiya, Aline Satie [UNESP] 08 February 2010 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:28:57Z (GMT). No. of bitstreams: 0
Previous issue date: 2010-02-08Bitstream added on 2014-06-13T19:37:36Z : No. of bitstreams: 1
takamiya_as_me_araca.pdf: 2744019 bytes, checksum: 436939ec1fb2e59f419b688a517c064c (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O objetivo do presente estudo foi verificar a atividade antimicrobiana de uma resina acrílica à base de poli (metil metacrilato) (PMMA) contendo nanopartículas de prata frente ao microorganismo Candida albicans. Utilizou-se a resina acrílica termopolimerizável Lucitone 550 e as nanopartículas de prata foram sintetizadas por meio da redução dos íons prata do nitrato de prata pelo citrato de sódio. A forma e o tamanho das partículas foram confirmados por microscopia eletrônica de varredura (MEV) e de transmissão (MET), tendo-se obtido partículas na forma esférica e com tamanhos médios de 5 e 10 nm. A resina acrílica foi proporcionada de acordo com as instruções do fabricante e a solução coloidal de nanopartículas de prata foi adicionada ao componente líquido da resina acrílica nas concentrações de 0,05%, 0,5% e 5% baseadas na massa do polímero. Após o processamento, os espécimes foram esterilizados por radiação de Co-60. Foram analisados a adesão de microorganismos à superfície do poli (metil metacrilato)/prata (PMMA/Ag) e a formação de biofilme por Candida albicans sobre a superfície polimérica através de microscopia de luz e de MEV. Os resultados mostraram redução estatisticamente significante (P < 0,05) da adesão de microorganismos à superfície do nanocompósito para os grupos com 0,05 e 0,5% de nanopartículas de prata com tamanho de 5nm quando comparados ao grupo controle. A microscopia de luz nãomostrou diferença na formação de biofilme entre os grupos dos nanocompósitos e o grupo controle. A MEV sugeriu uma redução na quantidade de células na superfície dos grupos contendo nanopartículas de prata, especialmente até 12 horas de crescimento fúngico. Os resultados sugerem ação inibitória sobre a adesão e formação de biofilme por Candida albicans quando da adição de nanopartículas de prata de tamanho 5 nm à resina acrílica nas concentrações de 0,05% e 0,5% / The aim of this study was to verify the antimicrobial activity of a poly (methyl methacrylate) acrylic resin containing silver nanoparticles against Candida albicans microorganism. The heat-polymerized acrylic resin Lucitone 550 was used and the silver nanoparticles were synthesized through the reduction of silver ions of silver nitrate by sodium citrate. The shape and size of the particles were confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and showed spherical particles with medium size of 5 and 10 nm. The acrylic resin was proportioned according to the manufacturer’s instructions and the silver nanoparticles colloid solution was added to the liquid of the acrylic resin in 0.05%, 0.5% and 5% of concentration based on the polymer mass. After being processing, the specimens were sterilized by Co-60 radiation. The adhesion of cells of Candida albicans and the biofilm formation on the surface of the polymer were evaluated by light microscopy and SEM. The results demonstrated significantly reduction (P < .05) of the microorganisms adhesion on the surface of the nanocomposites for the groups containing 0.05 and 0.5% of silver nanoparticles with size of 5nm when compared to the control group. The light microscopy did not show difference in the biofilm formation among the groups evaluated. The SEM images suggested reduction of growth of Candida albicans cells for the nanocomposite groups, mainly up to the period of 12 hours. It was concluded that the addition of silver nanoparticles with size of 5 nm to the PMMA in 0.05% and 0.5% concentrations showed antimicrobial effect against Candida albicans
|
77 |
Processamento e caracteriza??o de comp?sitos Poli(METACRILATO DE METILA)/S?lica (PMMA/SiO2)Silva, Erik dos Santos 05 April 2013 (has links)
Made available in DSpace on 2014-12-17T14:07:08Z (GMT). No. of bitstreams: 1
ErikSS_DISSERT.pdf: 3248804 bytes, checksum: 7241bc799da79c157edae8da7a7966cc (MD5)
Previous issue date: 2013-04-05 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Currently the search for new materials with properties suitable for specific applications has increased the number of researches that aim to address market needs. The poly (methyl methacrylate) (PMMA) is one of the most important polymers of the family of polyacrylates and polymethacrylates, especially for its unique optical properties and weathering resistance, and exceptional hardness and gloss. The development of polymer composites by the addition of inorganic fillers to the PMMA matrix increases the potential use of this polymer in various fields of application. The most commonly used inorganic fillers are particles of silica (SiO2), modified clays, graphite and carbon nanotubes. The main objective of this work is the development of PMMA/SiO2 composites at different concentrations of SiO2, for new applications as engineering plastics. The composites were produced by extrusion of tubular film, and obtained via solution for application to commercial PMMA plates, and also by injection molding, for improved the abrasion and scratch resistance of PMMA without compromising transparency. The effects of the addition of silica particles in the polymer matrix properties were evaluated by the maximum tensile strength, hardness, abrasion and scratch resistance, in addition to preliminary characterization by torque rheometry and melt flow rate. The results indicated that it is possible to use silica particles in a PMMA matrix, and a higher silica concentration produced an increase of the abrasion and scratch resistance, hardness, and reduced tensile strength / Atualmente a busca por novos materiais com propriedades adequadas para aplica??es espec?ficas vem aumentando o n?mero de pesquisas que visam suprir as necessidades do mercado. O poli(metacrilato de metila) (PMMA) ? um dos pol?meros mais importantes da fam?lia dos poliacrilatos e polimetacrilatos, principalmente pelas suas inigual?veis propriedades ?pticas e resist?ncia ?s intemp?ries, al?m de excepcional dureza e brilho. O desenvolvimento de comp?sitos polim?ricos por meio da adi??o de cargas inorg?nicas ? matriz de PMMA aumenta o potencial de uso deste pol?mero em diferentes ?reas de aplica??o. Dentre as cargas inorg?nicas mais utilizadas, podem-se destacar as part?culas de s?lica (SiO2), argilas modificadas, grafite e nanotubos de carbono. O objetivo principal deste trabalho ? o desenvolvimento de comp?sitos PMMA/SiO2, em diferentes concentra??es, para novas aplica??es como pl?stico de engenharia. Os comp?sitos foram produzidos por meio de extrus?o de filme tubular, e obtidos via solu??o, para aplica??o em chapas de PMMA comercial, e tamb?m por moldagem por inje??o, buscando o aumento da resist?ncia ? abras?o e ao risco do PMMA, sem comprometer a transpar?ncia. Os efeitos causados pela adi??o das part?culas de s?lica nas propriedades da matriz polim?rica foram avaliados atrav?s da resist?ncia m?xima ? tra??o, dureza, resist?ncia ? abras?o e ao risco, al?m das caracteriza??es preliminares por reometria de torque e ?ndice de fluidez. Os resultados indicaram que ? poss?vel utilizar part?culas de s?lica em uma matriz de PMMA, e que uma maior concentra??o de s?lica promoveu um aumento da resist?ncia ? abras?o e ao risco, dureza, e reduziu a resist?ncia m?xima ? tra??o
|
78 |
Efeito de argilas organof?licas na estrutura e propriedades de nanocomp?sitos de poli(metacrilato de metila)Rodrigues, Lourdes Aparecida Ribeiro 17 May 2013 (has links)
Made available in DSpace on 2014-12-17T14:07:18Z (GMT). No. of bitstreams: 1
LourdesARR_TESE.pdf: 12458480 bytes, checksum: 0efd4ff8bfb0c0bf6bcd3c18e449a690 (MD5)
Previous issue date: 2013-05-17 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Nacomposites of polymers and lamellar clayminerals, has generated high scientific and technological interest, for having mechanical properties and gas barriers differentiated of polymers and conventional composites. In this work, it was developed nanocomposites by single screw extruder and injection, utilizing commercial raw material, with the goal to investigate the quality of new developed materials. It was evaluated the influence of the content and the kind of clay in the structure and in the nanocomposites properties. It was used regular and elastomeric poly (methyl methacrylate) (Acrigel LEP 100 and Acrigel ECP800) and six montmorillonites (Cloisite 10A, 11B, 15A, 20A, 25A e 30B) at the concentration of 1% e 3% in weight. The nanocomposites were characterized by X-ray diffraction (XRD), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), colorimetric, optical transparency, flexural and tensile tests, Rockwell hardness and esclerometry. It was founded that is possible to obtain intercalated and exfoliated nanocomposites PMMA/MMT, and the top results was obtained in the materials with 1%in clay weight organophilizated with 2M2HT (Cloisite 15A and 20A) presented intercalate and hybrid morphology (exfoliated and flocullated). The ones that was produced with organophilizated clay with 2MHTL8 (Cloisite 30B) had excellent visual quality, but the majority presented hybrid morphology. In the materials processed with organophilizated clay with MT2ETOH (Cloisite 30B), there were color change and loss of transparency. It occurs improvement in a few mechanical properties, mainly in the materials produced with PMMA elastomeric (Acrigel ECP800), being more significant, the increase in the resistance to stripping in those nanocomposites / Nanocomp?sitos de pol?meros e argilominerais lamelares t?m gerado alto interesse cient?fico e tecnol?gico por possu?rem propriedades mec?nicas e de barreira ? g?s diferenciadas de pol?meros e de comp?sitos convencionais. Neste trabalho, foram desenvolvidos nanocomp?sitos por meio de extrusora monorosca e injetora, utilizando mat?rias-primas comerciais, com a finalidade de investigar a qualidade dos novos materiais desenvolvidos. Foi avaliada a influ?ncia do teor e do tipo de argila na estrutura e nas propriedades dos nanocomp?sitos. Foram usados PMMA comum e elastom?rico (Acrigel? LEP100 e Acrigel? ECP800) e seis argilas montmorilonitas (Cloisite? 10A, 11B, 15A, 20A, 25A e 30B) nas concentra??es de 1% e 3% em peso. Os nanocomp?sitos foram caracterizados por difra??o de raios X (DRX), termogravimetria (TGA), microscopia eletr?nica de transmiss?o (MET), colorimetria, transpar?ncia ?ptica, ensaios de tra??o uniaxial, flex?o, dureza Rockwell e esclerometria. Constatou-se que ? poss?vel obter nanocomp?sitos PMMA/MMT intercalados e esfoliados, sendo os melhores resultados obtidos nos materiais processados com 1% em peso de argilas organofilizadas com 2MBHT (Cloisite? 10A e 11B). Materiais produzidos com argilas organofilizadas com 2M2HT (Cloisite? 15A e 20A) apresentaram morfologia intercalada e h?brida (esfoliada e floculada). J? os produzidos com argilas organofilizadas com 2MHTL8 (Cloisite? 25A) tiveram excelente qualidade visual, por?m a maioria apresentou morfologia h?brida. Nos materiais processados com argilas organofilizadas com MT2ETOH (Cloisite? 30B) houve altera??o na cor e perda da transpar?ncia. Houve melhoria em algumas propriedades mec?nicas, principalmente nos materiais produzidos com PMMA elastom?rico (Acrigel? ECP800), sendo mais significativo, o aumento na resist?ncia ao riscamento nesses nanocomp?sitos
|
79 |
Influência da proporção do HEMA nas propriedades de uma resina adesiva experimentalCollares, Fabrício Mezzomo January 2007 (has links)
O objetivo deste estudo é caracterizar a influência da relação dos componentes hidrófilos de uma resina adesiva experimental em suas propriedades intrínsecas. Para isso, foram adicionados a um sistema polimérico (BisGMA, BisEMA e TEGDMA), diferentes concentrações de HEMA totalizando quatro grupos: 0%, 15%, 30% e 50% de HEMA. As misturas foram caracterizadas quanto à cinética de polimerização através de Fourier Transformed Infrared (FTIR) em tempo real e a taxa de polimerização (RP) foi calculada através da análise de regressão não-linear; resistência coesiva à tração utilizando-se uma máquina de ensaios mecânicos com corpos de prova em forma de ampulheta com área de constrição de 1mm2; e, sorção e solubilidade baseada na normatização ISO 4049. Houve correlação entre o tempo de fotoativação e o grau de conversão para todos os grupos (r2>0.98). O grupo 0% apresentou RPMÁX elevada nos segundos iniciais de fotoativação com, no entanto, uma brusca redução. As adições de 30% e 50% de HEMA determinaram uma RPMÁX do copolímero menor que em 15% e 0%. Não houve diferença entre o grau de conversão final (60s) entre os grupos de 0, 15 e 30%, sendo 59,7%, 61,4% e 55,2% respectivamente. As adições de 30% e 50% de HEMA determinaram a redução da resistência coesiva dos polímeros (p<0,05) quando comparado aos grupos 0% e 15%. Grupos com maiores adições de HEMA apresentaram maiores graus de sorção e solubilidade (p<0,05). Maiores adições de HEMA resultaram em polímeros mais propensos à degradação. / The aim of this study was to characterize the influence of hydrophilic monomers ratios on an experimental adhesive resin properties. Four groups, with 0, 15, 30 and 50% (wt) addiction of HEMA were prepared. Comonomer blends (BisGMA, BisEMA, TEGDMA and HEMA) were analyzed with kinetics of polimerization real time FTIR and the rate of polymerization was calculated by non-linear regression analysis. Ultimate tensile strength was tested using a universal testing machine (Emic) with hour-glass shaped specimens with cross-sectional area 1mm2. Water sorption and solubility tests were based on ISO 4049. For All groups was a positive and strong correlation between light-activation time and degree of conversion (r2>0,98). Group 0% of HEMA showed higher RPMÁX in early seconds with a suddenly decrease. Additions of 30% and 50% of HEMA determined a RPMÁX lower than the comonomer blends with 15% and 0% of HEMA. There was no statistical difference of final degree of conversion of the tested groups, varying from 63% to 67% . The additions of 30% and 50% of HEMA determined reduction of ultimate tensile strength of the polymers formed (p<0,05) when compared to 0% and 15 % of HEMA. Groups with higher additions of HEMA showed higher water sorption and solubility (p<0,05). Higher additions of HEMA resulted in polymers more prone to degradation.
|
80 |
Sistemas adesivos a base de acrilamidas : síntese, caracterização e desenvolvimento / Acrylamides adhesive system : synthesis, characterization and development.Rodrigues, Stefani Becker January 2016 (has links)
O objetivo deste estudo foi sintetizar e caracterizar monômeros metacrilamidas, desenvolver, caracterizar e avaliar as propriedades de sistemas adesivo convencional de três passos. Foram sintetizadas bis(metacrilamida)s e tris(metacrilamida) e caracterizadas por espectroscopia de Infravermelho por Transformada de Fourier (FTIR), Ressonância Magnética Nuclear (RMN) de 1H e 13C, por Cromatografia Líquida de Alta Eficiência com Espectrometria de Massas (UHPLC-QTOF-MS) e Calorimetria Exploratória Diferencial Modulada (MDSC). Quatro bis(metacrilamidas), (1) N,N’-(propane-1,3-diyl)bis(N-ethyl-2-methylacrylamide), (2) N,N’-(octane-1,8-diyl)bis(2-methylacrylamide), (3) N,N’-(butane-1,4-diyl)bis(2-methacrylamide) e (4) N,N’-(1,4 phenylene)bis(2-methylacrylamide)monômero (1), (2), (3) e (4), e uma tris(metacrilamida) TMA, foram sintetizadas. Pela análise de FTIR-ATR foram observadas as bandas correspondentes ao estiramento do grupo C=O (1660 cm-1), C=C (1610 cm-1), N-H (3300 cm-1) e C-N (1520 cm-1). As análises de RMN identificaram a presença das ligações duplas referentes aos grupos metacrilamidas em deslocamentos químicos entre 5,3 e 5,8 ppm para 1H e entre 120 e 140 ppm para 13C.Os valores de massa exata m/z foram: 267,2068, 281,2222, 225,1595, 245,1283 e 351,2385 g/mol para os monômeros (1), (2), (3), (4) e TMA, respectivamente. A cinética de polimerização do TMA e dos adesivos experimentais contendo 2-hidroxietil acrilamida (HEAA) ou 2-hidroxietil metacrilato (HEMA) com as seguintes formulações foram investigadas por meio de DSC-PCA, n=3: TMA33%/HEAA66%, TMA50%/HEAA50%, TMA66%/HEAA33%, TMA50%/HEMA50%, BisGMA/HEAA/TMA e BisGMA/HEMA.Características e propriedades mecânicas das resinas adesivas BisGMA/HEAA/TMA e BisGMA/HEMA foram avaliadas por resistência coesiva (UTS, n=5), degradação em solvente (ΔKHN, n=5), ângulo de contato (n=5), microtração (μTBS, n=20) e análise de fratura. Um primer a base de acrilamidas foi desenvolvido (H2O/HEAA/AMPS) (2-acrylamida-2-methilpropano ácido sulfônico) para ser utilizado no grupo experimental com metacrilamidas. Os valores de pH e ângulo de contato do primer experimental foram comparados com o primer do ScotchBond Multi-purpose (grupo controle). O monômero (1) resultou em um monômero amarelo claro de baixa viscosidade, entretanto, não apresentou foto ou termopolimerização. A energia de ativação determinada pelo método de Kissinger foi – 165,8 kJmol-1; -182,7 kJmol-1 e -156,7 kJmol-1 para os monômeros (2), (3) e (4), respectivamente. Sistemas adesivos convencionais de três passos a base de metacrilamidas e a base de metacrilatos foram desenvolvidos. Resinas adesivas contendo somente HEAA e TMA (TMA33%/HEAA66%, TMA50%/HEAA50%, TMA66%/HEAA33%) apresentaram grau de conversão abaixo de 40% após 40 s de fotoativação. Alto grau de conversão (acima de 60%) só foi encontrado para as resinas adesivas BisGMA/HEAA/TMA e BisGMA/HEMA e sem diferença significativa entre elas, p>0,05. Os valores de UTS (BisGMA/HEMA- 67,7 ±5 MPa e BisGMA/HEAA/TMA- 60,5 ±7 MPa), μTBS (BisGMA/HEMA- 57 ± 14 MPa e BisGMA/HEAA/TMA- 53,1 ±15 MPa) e ângulo de contato (BisGMA/HEMA- 39,5 ±9 e BisGMA/HEAA/TMA- 46,7 ±15) não apresentaram diferença estatística, p>0.05. O primer experimental apresentou um valor pH mais baixo (2,7) bem como de ângulo de contato (18,5 ±5) em relação ao comercial (pH-4 e θ-33,5 ±4). A síntese proposta para os monômeros (1), (2), (3), (4) e TMA foi caracterizada nesse trabalho. Um primer somente com acrilamidas foi desenvolvido e a presença do novo monômero TMA na resina adesiva BisGMA/HEAA permitiu a formulação de um sistema adesivo convencional de três passos sem a presença do monômero HEMA. / The aim of this study was synthesized and characterizes methacrylamides monomers, development, characterizer and evaluated the properties of 3-step etch-and-rise adhesive system. Bis(methacrylamide)s and tris(methacrylamide) were synthesized. The monomer structures were confirmed by 1H and 13C Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR-ATR), Ultra-high liquid chromatography quadrupole time of flight mass spectrometry (UHPLC-QTOF-MS) and modulated differential scanning calorimetry (mDSC). Four bis(methacrylamide)s monomers (1) N,N’-(propane-1,3-diyl)bis(N-ethyl-2-methylacrylamide), (2) N,N’-(octane-1,8-diyl)bis(2-methylacrylamide), (3) N,N’-(butane-1,4-diyl)bis(2-methacrylamide) and (4) N,N’-(1,4 phenylene)bis(2-methylacrylamide) and one tris(methacrylamide), TMA, were synthesized. All IR spectra of the monomers showed the C=C axial deformation at 1610 cm-1. The 1H NMR spectra the olefinic hydrogens were observed at 5.3 an 5.8 ppm and in the 13C NMR, the vinylic carbons at 120 and 140 ppm. The exact m/z values were: 267.2068, 281.2222, 225.1595, 245.1283 and 351.2385 g/mol for monomers (1), (2), (3), (4) and TMA respectively. Monomer (1) not presented photo (DSC-PCA) or thermal polymerization. The activation energy determined using Kissinger methodology was: - 165.8 kJmol-1; -182.7 kJmol-1 and -156.7 kJmol-1 for monomers (2), (3) and (4), respectively. 3-step adhesive systems with methacrylamides and methcrylates were development. Kinetics of photopolymerization of TMA and experimental adhesive resin containing 2-hydroxyethylacrylamide (HEAA) or 2-hydroxyethylmethacrylate (HEMA) in the following formulations: (TMA 33%/HEAA 66%, TMA 50%/HEAA 50%, TMA66%/HEAA33%, TMA50%/HEMA50%, BisGMA66%/HEAA24%/TMA10% and BisGMA66%/HEMA33%) were investigated through DSC-PCA. Characteristics and mechanical properties for BisGMA 66%/HEAA 24%/TMA 10% and BisGMA 66%/HEMA 33% adhesives were evaluated with ultimate tensile strength (UTS, n=5), softening in solvent (ΔKHN, n=5), contact angle (n=5), microtensile bond strength (μTBS, n=20) and failure analysis. A primer was also formulated with H2O/HEAA/AMPS (2-acrylamido-2-methylpropane sulfonic acid) and the pH and contact angle value were verified and compared to commercial ScotchBond primer. Adhesive resin with HEAA and TMA (TMA33%/HEAA66%, TMA50%/HEAA50%, TMA66%/HEAA33%) showed lower conversion and polymerization rate after 40 s of light activation. Higher conversion (up to 60%) was found for BisGMA/HEAA/TMA and BisGMA/HEMA adhesive resin without significant difference between adhesive resin, p>0.05. UTS (BisGMA/HEMA- 67.7 ±5 MPa e BisGMA/HEAA/TMA- 60.5 ±7 MPa), immediate μTBS (BisGMA/HEMA- 57 ± 14 MPa e BisGMA/HEAA/TMA- 53.1 ±15 MPa), ΔKHN (BisGMA/HEMA- 56 ± 7 e BisGMA/HEAA/TMA- 64 ±4) and contact angle (BisGMA/HEMA- 39.5 ±9 e BisGMA/HEAA/TMA- 46.7 ±15) showed no statistical difference, p>0.05. The experimental primer presented more acidity pH (2.7) and lower contact angle (18.5 ±5) when compared to commercial primer (pH- 4 e θ- 33.5 ±4). A new acrylamide based-primer was formulated and the presence of the new tris(methacrylamide) monomer (TMA) was enable the preparation of a 3-step etch-and-rise adhesive system without HEMA monomer.
|
Page generated in 0.0589 seconds