Polymer adsorption at solid-liquid interfaces

Kawaguchi, Masami; Takahashi, Akira

doi:10.1016/0001-8686(92)80085-c

Cited by 169 publications

(101 citation statements)

References 228 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In recent years much scientific research into the properties of adsorbed macromolecules has focused on understanding basic properties such as film thickness, coverage, and segment density distribution in the near-surface region. [12][13][14] The results of these studies provide a comprehensive description of adsorbed polymer layers under equilibrium conditions.…”

Section: Introductionmentioning

confidence: 99%

Effects of conformational isomerism on the desorption kinetics of n-alkanes from graphite

Paserba

Gellman

2001

The Journal of Chemical Physics

135

175

View full text Add to dashboard Cite

The dynamics of oligomer desorption from surfaces have been studied by measuring the desorption kinetics of a set of n-alkanes from the surface of single crystalline graphite. Desorption rates were measured using a set of 21 monodispersed n-alkanes (C N H 2Nϩ2 ,5рNр60) each adsorbed at coverages in the range Ͻ0.1 to Ͼ1 monolayers. Desorption is observed to be a first-order process with a desorption barrier (⌬E des ‡ ) that is independent of coverage. The pre-exponential of the desorption rate constant is independent of the oligomer chain length and has a value of ϭ10 19.6Ϯ0.5 s Ϫ1 . We also find that ⌬E des ‡ has a nonlinear dependence on chain length and takes the empirical form ⌬E des ‡ ϭaϩbN ␥ , with the exponent having a value of ␥ϭ0.50Ϯ0.01. More interestingly, we have proposed a mechanism for the desorption process and a model for the energetics and the entropy of the oligomers on the surface that provide an extremely good quantitative fit to the observed chain length dependence of ⌬E des ‡ . ⌬E des ‡ is given by the difference in energy between the gas phase n-alkane and the conformation of the adsorbed n-alkane with the minimum free energy at the desorption temperature. These results reveal that conformational isomerism plays a significant role in determining the desorption kinetics of oligomers from surfaces.

show abstract

Section: Introductionmentioning

confidence: 99%

Effects of conformational isomerism on the desorption kinetics of n-alkanes from graphite

Paserba

Gellman

2001

The Journal of Chemical Physics

135

175

View full text Add to dashboard Cite

show abstract

“…Na literatura são encontradas dezenas de trabalhos que tratam do tema [18][19][20][21][22][23] , revelando que mecanismos genéricos ainda não podem ser propostos, uma vez que sistemas muito diferentes têm sido investigados. Em filmes formados por camadas de polieletrólitos, o processo de automontagem é governado por interações eletrostáticas entre seus grupos iônicos, levando à formação de pares iônicos 18 .…”

Section: Processos De Adsorção Em Filmes Automontadosunclassified

Filmes poliméricos ultrafinos produzidos pela técnica de automontagem: preparação, propriedades e aplicações

Paterno¹,

Mattoso²,

Oliveira³

2001

Quím. Nova

View full text Add to dashboard Cite

Recebido em 12/6/00; aceito em 16/8/00 ULTRATHIN POLYMER FILMS PRODUCED BY THE SELF-ASSEMBLY TECHNIQUE: PREPARATION, PROPERTIES AND APPLICATIONS. The self-assembly technique is a powerful tool to fabricate ultrathin films from organic compounds aiming at technological applications in molecular electronics. This relatively new approach allows molecularly flat films to be obtained on a simple and cheap fashion from various types of material, including polyelectrolytes, conducting polymers, dyes and proteins. The resulting multilayer films may be fabricated according to specific requirements since their structural and physical properties may be controlled at the molecular level. In this review we shall comment upon the evolution of preparation methods for ultrathin films, the process of adsorption and their main properties, as well as some examples of technological applications of layer-by-layer or selfassembled films.Keywords: self-assembly; ultrathin films; polyions; layer-by-layer films. Quim. Nova, Vol. 24, No. 2, 228-235, 2001. Revisão INTRODUÇÃOA partir da década de 60, moléculas orgânicas passaram a receber atenção especial, devido à possibilidade de seu emprego em dispositivos eletrônicos e óticos, principalmente após a descoberta de condução elétrica em cristais formados pela combinação de moléculas doadoras e aceitadoras de carga, como o tetratiofulvaleno (TTF) e o tetracianoquinodimetano (TCNQ)1 . O potencial tecnológico de materiais orgânicos foi reconhecido, em função de sua variedade de propriedades elétricas, óti-cas e magnéticas. É provável que num futuro próximo, materiais orgânicos como corantes, polímeros condutores e proteí-nas passem a competir com os materiais inorgânicos no setor eletrônico, principalmente pelo seu baixo custo de produção e/ ou disponibilidade e pela variedade de propriedades/aplicações. Além disso, métodos de processamento e de fabricação de filmes ultrafinos 2 vêm sendo desenvolvidos paralelamente para que as propriedades destes materiais possam vir a ser exploradas futuramente em escala comercial.As possíveis aplicações dos materiais orgânicos incluem óti-ca integrada, sensores, recobrimentos para redução de fricção, agentes de superfície para orientação de camadas e em dispositivos de heterojunções, como diodos emissores de luz 2,3 . O desenvolvimento de técnicas de fabricação de filmes ultrafinos foi impulsionado pela necessidade de se obter estruturas organizadas, com controle de espessura e de propriedades em escala molecular. Os métodos de Langmuir-Blodgett (LB) 4 e de automontagem 5 despontam como os mais promissores neste aspecto, uma vez que permitem "organizar" moléculas individuais em arquiteturas altamente ordenadas 2 , propiciando ainda o planejamento das propriedades finais dos filmes obtidos, por exemplo, através da incorporação de cromóforos apropriados, grupos funcionais, e variação da espessura das camadas. Outro aspecto interessante nesta área científico-tecnológica é a sua interdisciplinaridade, que envolve profissionais das áreas de física, química, bio...

show abstract

“…[16][17][18][19][20][21] have been used to characterize the adsorption conformation and adsorption mechanism of polyelectrolytes (e.g., PDADMAX salts, etc.). However, in low ionic strength solutions, polyelectrolytes adsorbed at an oppositely charged surface forms thin layers.…”

Section: Introductionmentioning

confidence: 99%

Effect of nitrate or sulfate on flocculation properties of cationic polymer flocculants

Tian

Pan

et al. 2007

Desalination

View full text Add to dashboard Cite

The objective of this study was to investigate the effect of different counterions on the flocculation of cationic polymer flocculants and to obtain new high efficient flocculants by modifying polydiallyldimethylammonium chloride (PDADMAC) with different counterions. The effect of nitrate or sulfate as counterions on flocculation properties of polydiallyldimethylammonium salts (PDADMAX) was investigated in the conventional jar test procedure by using optical monitoring technique and zeta potential measurement. Moreover, in order to indicate the flocculation mechanism of PDADMAX having different counterions, the effect of counterions on the solution property and adsorption conformation of PDADMAX was studied by reduced viscosity and atomic force microscopy (AFM). The experiment results show that counterions have a significantly different effect on PDADMAX flocculation where "adsorption charge neutralization action" and "adsorption bridging action" play different parts. PDADMAX having NO 3 ! has stronger "adsorption charge neutralization action" and its turbidity removal is 98%, whereas PDADMAX having SO 4 2! has stronger "adsorption bridging action", as well as the wider optimum dosage and larger floc size. In particular, the flocculation efficiency of PDADMAX having different contents of SO 4 2! or NO 3 ! is different. The optimum content of SO 4 2! or NO 3 ! is 20%.

show abstract

Polymer adsorption at solid-liquid interfaces

Cited by 169 publications

References 228 publications

Effects of conformational isomerism on the desorption kinetics of n-alkanes from graphite

Effects of conformational isomerism on the desorption kinetics of n-alkanes from graphite

Filmes poliméricos ultrafinos produzidos pela técnica de automontagem: preparação, propriedades e aplicações

Effect of nitrate or sulfate on flocculation properties of cationic polymer flocculants

Contact Info

Product

Resources

About