Latex Fractionation by Sedimentation and Colloidal Crystallization: The Case of Poly(styrene-co-acrylamide)

Teixeira‐Neto, Érico; Leite, Carlos A. P.; Cardoso, André Luiz Herzog; Silva, Maria do Carmo Vasconcelos Medeiros da; Braga, Melissa; Galembeck, Fernando

doi:10.1006/jcis.2000.7135

Cited by 14 publications

(15 citation statements)

References 27 publications

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“…Although the intensity is different, both curves show similar peaks. It was previously shown that the absorption peaks of a PAM fraction appear at 3190 cm −1 (N–H stretching), 3427 cm −1 (N–H vibration), 1654 cm −1 (CO stretching), and 1105 and 1420 cm −1 (C–N stretching), and the St fraction absorption peaks that appear at 1654 and 1493 cm −1 (aromatic ring deformation), 906, 756, 700 and 557 cm −1 correspond to benzyl groups. The appearance of these peaks supports that the dynamic sonication polymerization technique has resulted in PS‐ b ‐PAM.…”

Section: Resultsmentioning

confidence: 97%

Synthesis of styrene–acrylamide copolymer by surfactant‐free sonicated dynamic interfacial polymerization

Suckeveriene

Rahman

Shtein

et al. 2011

Polymers for Advanced Techs

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This paper summarizes a study on emulsifier-free ultrasonically assisted in situ dynamic interfacial emulsion copolymerization process of acrylamide and styrene. The resulting emulsions are stable and uniform for several months. Thermogravimetric analysis (TGA) curves and reaction conversion measurements have provided an important knowledge regarding the emulsifier-free polymerization method. Solvent extractions (water, methanol, and xylene) have shown that the polymerization product is essentially a styrene-acrylamide copolymer. The copolymer produced is a block copolymer, PS-b-PAM, where each block contains small amounts of the other comonomer. The produced emulsions are film forming at room temperature in spite of the very high block T g s, owing to a unique water plasticization effect of the polyacrylamide blocks. Some films prepared from the PS-b-PAM have resulted in clear and transparent films. The presented interfacial dynamic polymerization process is fast, reaching 81% conversion within 2 hr of sonication at 4 C (low temperature owing to molecular weight and kinetic considerations), and produces very stable PS-b-PAM emulsions. TGA was extensively used as an analytical tool for determination of the reaction parameters and composition of the acrylamide-styrene copolymers.

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Section: Resultsmentioning

confidence: 97%

Synthesis of styrene–acrylamide copolymer by surfactant‐free sonicated dynamic interfacial polymerization

Suckeveriene

Rahman

Shtein

et al. 2011

Polymers for Advanced Techs

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“…Both small and large particles underwent extensive deformation, even though the smaller particles should be more strongly deformed by capillary forces. However, from previous results from this laboratory we suggest that the larger particles are chemically different from the smaller ones, and the resulting heterogeneity in particle viscoelastic and interfacial properties is relevant to the particle deformation analysis. − …”

Section: Discussionmentioning

confidence: 70%

Electric Charge Clustering and Migration in Latex Films: A Study by Scanning Electric Potential Microscopy

2001

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Scanning electric potential microscopy images were acquired from coalesced poly (styrene-butyl acrylateacrylic acid) latex films having a Tg equal to 15.9 °C. The micrographs show the boundaries between particles even in transparent films (transmittance > 99%), and the boundaries appear as positive domains, relative to the particle cores. Large local electric potential gradients are observed, ca. 1 V/10 nm, but these are smeared when the latex is dialyzed prior to film formation. Electric domain patterns are modified by aging, annealing and exposure to toluene or chloroform vapors. Completely independent patterns are obtained, in each case. The significance of charge distribution to latex cohesion, adhesion and swelling behavior is discussed.

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“…No caso do PS-AAM, a maciez periférica é fácil de compreender, considerando os resultados microanalíticos e topoquímicos obtidos anteriormente neste laboratório, para este látex: a casca das partículas é mais rica em acrilamida que o seu interior, e esta é plastificada pela umidade ambiente [5] . Por outro lado, o NRL é formado por partículas macias de poliisopreno, rodeadas por cascas ricas em material iônico, que seca formando domínios de maior dureza que a borracha.…”

Section: R R R R Resultados E Discussão Esultados E Discussão Esultadunclassified

Heterogeneidade da Capacidade Dissipativa e do Módulo de Young em Superfícies Poliméricas: Contraste de Fase em AFM com Contato Periódico

Costa¹,

Rippel²,

Galembeck³

2002

Polímeros

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O contraste de fase em microscopia de força atômica no modo de contato periódico é determinado pela topografia, viscoelasticidade e pelas propriedades adesivas das amostras. A maximização da quantidade de informação extraída das imagens exige que o procedimento de aquisição seja previamente definido através da escolha adequada do ângulo de fase entre a onda aplicada ao cristal piezoelétrico, que provoca a oscilação da sonda, e a onda gerada pela resposta do fotodetector. O efeito da topografia no contraste de fase é minimizado somente se as duas senóides (oscilação da sonda e resposta do fotodetector) forem ortogonais. Escolhendo teta = -90°, os domínios brilhantes na imagem são mais dissipativos que os domínios escuros, porém o oposto é observado usando teta = +90°. Esta regra é obtida da análise de operação do instrumento, e é experimentalmente verificada com uma amostra preparada pelo recobrimento parcial de uma superfície de mica com um filme de borracha natural. Três diferentes filmes foram analisados e revelaram diferentes padrões de domínios: domínios duros em uma matriz mole são observados em um látex copolimérico sintético, enquanto que um filme de borracha natural apresenta domínios moles em uma matriz mais dura, e um filme compósito de borracha natural com polifosfato de sódio é formado por domínios duros e moles, interpenetrantes.

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Latex Fractionation by Sedimentation and Colloidal Crystallization: The Case of Poly(styrene-co-acrylamide)

Cited by 14 publications

References 27 publications

Synthesis of styrene–acrylamide copolymer by surfactant‐free sonicated dynamic interfacial polymerization

Synthesis of styrene–acrylamide copolymer by surfactant‐free sonicated dynamic interfacial polymerization

Electric Charge Clustering and Migration in Latex Films: A Study by Scanning Electric Potential Microscopy

Heterogeneidade da Capacidade Dissipativa e do Módulo de Young em Superfícies Poliméricas: Contraste de Fase em AFM com Contato Periódico

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