Single-chain collapse or precipitation? Kinetic diagram of the states of a polymer solution

Grosberg, Alexander Y.; Кузнецов, Д. В.

doi:10.1021/ma00068a027

Cited by 95 publications

(94 citation statements)

References 4 publications

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“…solvent strength is required in order to make more dilute polymer solutions cross binodal and spinodal lines (20). Comparison of the solvent composition at the inflection point for different trans-AABNTBA copolymer samples showed that the water/THF ratio increased from 0.60 to 0.65 on increasing the NTBA content from 0 to about 40% and then decreased to about 0.54 (Fig.…”

Section: Aab (Mol%)mentioning

confidence: 97%

“…Both methods decrease the thermodynamic strength of the solvent, thus reducing the solvation of polymer macromolecules. This decrease causes the system to cross binodal or spinodal lines in the phase diagram (20,21) and formation of metastable polymer solutions or phase separation of polymeric materials is observed. However, to evaluate the possible effect of trans-cis photoisomerization, it was necessary that the thermal back-isomerization rate did not change too much in different runs.…”

Section: Polymer Precipitationmentioning

confidence: 99%

See 1 more Smart Citation

Photomodulation of the hydrophilic properties of acrylic polymers containing side-chain azobenzene chromophores

Tirelli¹,

Altomare²,

Ciardelli³

et al. 1995

Can. J. Chem.

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Partially hydrophilic polymers have been prepared by free-radical copolymerization of trans-4-acryloyloxyazobenzene with N-tert-butylacrylamide and N-isopropylacrylamide. A turbidimetric method has been adapted to investigate the dependence of the polymer hydrophilic-hydrophobic balance on chemical composition and extent of photoisomerization of side-chain azobenzene chromophores. Irradiation at 366 nm of polymer suspension in THF-water induces the isomerization of azobenzene groups from the planar apolar trans form to the nonplanar polar cis form. Correspondingly, the solution turbidity is appreciably modified. Experimental results are discussed in terms of polymer structural parameters. Suspension stability and the possibility of canying out photochemical cycles have been also investigated.Key words: photochromic polymers, photoresponsive polymer, photomodulation of polymer properties, azobenzene-containing polymers, acryloyloxyazobenzene, N-tert-butylacrylamide.Rksumk : On a prCpart des polymkres partiellement hydrophiles par copolymCrisation radicalaire du trans-4-acryloxyazobenzkne avec les N-tert-butylacrylarnide et N-isopropylacrylamide. On a adapt6 une mCthode turbidimktrique pour Ctudier la dCpendance de la balance hydrophile-hydrophobe sur la composition chimique et le degrC de photoisomCrisation de la chaine latCrale des chromophores azobenzknes. L'irradiation, 2i 360 nm, d'une suspension de polymkre dans un melange THF-eau induit une isomCrisation des groupes azobenzknes de la forme trans, plane et apolaire, vers la forme cis, non planaire et polaire. D'une faqon correspondante, la turbiditt de la solution est modifiee d'une faqon appreciable. On discute des risultats expCrimentaux en fonction des paramktres structuraux du polymkre. On a CtudiC la stabilitt de la suspension et la possibilitC d'effectuer des cycles photochimiques.Mots elks : polymkres photochromes, polymkre photorepondant, photomodulation des propriCtCs d'un polymkre, polymkres contenant de l'azobenzkne, acryloxyazobenzkne, N-tert-butylacrylamide. [Traduit par la rCdaction]In recent years increasing attention has been focused on polymeric systems and gels based on N-alkylacrylamide, for their well-known properties of thermoreversible swelling or collapse, and for their possible application as drug release systems, chemo-mechanical transducers, sensors, and selective pumps (1-5). Polymer gelation can also be controlled by

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Section: Aab (Mol%)mentioning

confidence: 97%

Section: Polymer Precipitationmentioning

confidence: 99%

Photomodulation of the hydrophilic properties of acrylic polymers containing side-chain azobenzene chromophores

Tirelli¹,

Altomare²,

Ciardelli³

et al. 1995

Can. J. Chem.

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“…In this review, we focus on a description of the concepts borrowed directly from polymer physics [20][21][22][23][24][25][26][27][28] that provide the necessary framework for understanding the driving forces and mechanisms for protein aggregation. In our parlance, protein aggregation refers is allencompassing because we do not distinguish between ordered versus amorphous aggregates.…”

Section: Introductionmentioning

confidence: 99%

A polymer physics perspective on driving forces and mechanisms for protein aggregation

Pappu

Wang

Vitalis

et al. 2008

Archives of Biochemistry and Biophysics

154

172

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Protein aggregation is a commonly occurring problem in biology. Cells have evolved stress-response mechanisms to cope with problems posed by protein aggregation. Yet, these quality control mechanisms are overwhelmed by chronic aggregation-related stress and the resultant consequences of aggregation become toxic to cells. As a result, a variety of systemic and neurodegenerative diseases are associated with various aspects of protein aggregation and rational approaches to either inhibit aggregation or manipulate the pathways to aggregation might lead to an alleviation of disease phenotypes. To develop such approaches, one needs a rigorous and quantitative understanding of protein aggregation. Much work has been done in this area. However, several unanswered questions linger, and these pertain primarily to the actual mechanism of aggregation as well as to the types of intermolecular associations and intramolecular fluctuations realized at low protein concentrations. It has been suggested that the concepts underlying protein aggregation are similar to those used to describe the aggregation of synthetic polymers. Following this suggestion, the relevant concepts of polymer aggregation are introduced. The focus is on explaining the driving forces for polymer aggregation and how these driving forces vary with chain length and solution conditions. It is widely accepted that protein aggregation is a nucleation-dependent process. This view is based mainly on the presence of long times for the accumulation of aggregates and the elimination of these lag times with "seeds". In this sense, protein aggregation is viewed as being analogous to the aggregation of colloidal particles. The theories for polymer aggregation reviewed in this work suggest an alternative mechanism for the origin of long lag times in protein aggregation. The proposed mechanism derives from the recognition that polymers have unique dynamics that distinguish them from other aggregation-prone systems such as colloidal particles.

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“…22,23 The van der Waals interaction driving the coil-toglobule transition in an organic solvent is very weak; thus, the individual chains can hardly reach the single chain globule state before the interchain aggregation (demixing) occurs. 24 This is why it has been very difficult to observe fully collapsed thermodynamically stable single chain globules in those systems. Aqueous solutions of temperature responsive polymers like PNIPAAm, on the other hand, allow the observation of thermodynamically stable globular states of single chains.…”

Section: Introductionmentioning

confidence: 99%

Monte Carlo study of the coil‐to‐globule transition of a model polymeric system

Rissanou

Anastasiadis

Bitsanis

2006

J Polym Sci B Polym Phys

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Monte Carlo computer simulations of single, flexible, self-avoiding chains on a cubic lattice have been performed upon conditions of increasing segment-segment cohesive energy (deteriorating solvent quality). The simulations spanned a wide range of chain lengths (20-10,000, i.e., up to molecular weights of a few millions) and cohesive energies (0.0-0.45k B T, i.e., from athermal to very poor solvents). The chain length dependence of the chain size in poor solvents was characterized by a wide plateau of almost null growth for intermediate chain lengths. This plateau was linked to the development of the incipient constant density core, while genuine power law dependence (1/3) was not reached even for the longest chains and poorest solvents simulated here. The mere appearance of a core required substantial chain lengths (higher than 1000; molecular weights of a few hundred thousands), while short chains underwent a gradual densification devoid of any qualitative changes in the density distribution. Sufficiently long chains became more but not quite spherical and underwent a reasonably sharp second order phase transition. The findings were generally in agreement with predictions of mean-field theory and with the use of the standard scaling variables, despite slight inconsistencies. Nevertheless, the results stress the fact that short chains never form a constant density core and that core-dominance on the globule's properties (''volume approximation'') is only valid for extraordinarily long chains [molecular weight of O( 10 9 )], an effect linked to the relatively diffuse nature of the surface layer and originating from chain connectivity in conjunction with spherical geometry.

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Single-chain collapse or precipitation? Kinetic diagram of the states of a polymer solution

Cited by 95 publications

References 4 publications

Photomodulation of the hydrophilic properties of acrylic polymers containing side-chain azobenzene chromophores

Photomodulation of the hydrophilic properties of acrylic polymers containing side-chain azobenzene chromophores

A polymer physics perspective on driving forces and mechanisms for protein aggregation

Monte Carlo study of the coil‐to‐globule transition of a model polymeric system

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