Nuclear reaction analysis: A study on the interface formation in polymer mixtures below the critical point

Steiner, Ullrich; Chaturvedi, U. K.; Zak, Omer; Krausch, Georg; Schätz, G.; Klein, Jacob

doi:10.1002/masy.19910450128

Cited by 7 publications

(6 citation statements)

References 10 publications

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“…The technique has been described in detail earlier. [27][28][29][30] Briefly, a beam of 3He ions accelerated to energy £3i0 is incident on the polymer film. The nuclear reaction 3He + 2H -4He + 7H + Q (Q = 18.3 MeV) takes place within the sample.…”

Section: Methodsmentioning

confidence: 99%

Diblock copolymers attached to homopolymer surfaces and interfaces

Budkowski¹,

Klein²,

Steiner³

et al. 1993

Macromolecules

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Nuclear reaction analysis (NRA) was used to study the segregation of an asymmetric diblock copolymer, consisting of polyisoprene (PI, molecular weight M = 104)/deuterated polystyrene (dPS, M = 105) blocks, to the interfaces formed by polystyrene (PS) homopolymer with various phases. PS/vacuum, PS/ silicon, and PS/PI homopolymer interfaces were investigated for different M values of the PS matrix (M = 1.7 X 103-330 X 103), and segregation isotherms were established as a function of temperature and of diblock concentration within the PS homopolymer. In all cases the diblocks attach to the interfaces by their PI moieties alone, to form brushlike structures of end-attached PS tails. The high spatial resolution of the NRA technique enabled studies of the brush conformation as a function of the attachment density at the PS/ vacuum surface and was used to characterize the extent of penetration of the PS matrix chains into the diblock brushes. Detailed analysis of the brush conformation and of the segregation isotherms, mainly in terms of a Flory-type mean field model based on those due to de Gennes and to Leibler, provided a consistent description of our data; it enabled the extraction of the PI/PS segmental interaction parameter xpips, yielding values in accord with scattering studies, and of the attachment energies of the PI diblock moiety to the PS/air and PS/silicon interfaces. The values of xpips extracted from our data using this Flory-type model were found to increase at lower M values of the PS matrix, in qualitative accord with previous results.

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Section: Methodsmentioning

confidence: 99%

Diblock copolymers attached to homopolymer surfaces and interfaces

Budkowski¹,

Klein²,

Steiner³

et al. 1993

Macromolecules

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“…Despite the widespread use of such systems, there remains a need to provide a fundamental understanding of how their mechanical properties are altered, and few techniques have proved suitable for studying such systems at a molecular level. Methods that have been used include NMR relaxation, − neutron scattering and reflection, , and other atomic/molecular scattering techniques . Diffusion studies may also provide information about the dynamics of the system and how the presence of the filler particles and the adsorption of polymer onto the particles affect molecular motion.…”

Section: Introductionmentioning

confidence: 99%

Diffusion of Poly(dimethylsiloxane) Mixtures with Silicate Nanoparticles

et al. 2000

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Pulsed field-gradient (PFG) NMR has been used to measure self-diffusion coefficients in mixtures of silicate nanoparticles with poly(dimethylsiloxane)s as a function of volume fraction of particles and of polymer molecular weight. Two different sizes of nanoparticles were used: the smaller acted like a solvent, and the larger one acted more like a colloidal particle. In the former case, two distinct diffusion coefficients were obtained, corresponding to the particle and the polymer. In the second case, only a signal from the polymer was evident because of the short spin-spin relaxation time (T 2) of the particle. However, in this latter case the diffusional attenuation indicated the presence of both free polymer and locally mobile but translationally constrained polymer, characteristic of polymer adsorption from a liquid. The data have been interpreted as a function of particle loading, and calculations have been made to estimate the thickness of the polymer layer using a hydrodynamic model.

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“…30,31 A Gaussian type function with a constant standard deviation, a measure of the spread of the IBF, is routinely inform ed as IBF for these techniques. [1][2][3][4][5][6][7][8][9][10][11][12][13][14]23,24 The case of CRM deser ves special attention and will be discussed in m ore detail. This experimental technique can be applied to study interphases by scanning the sample in the two m odes described before.…”

Section: Proposed Metho Do Log Ymentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9][10][11] Nuclear reaction analysis (NRA) has the same high intrinsic resolution, but only recently has it been applied to polymer studies. [12][13][14] This group of techniques is based on hitting the sample surface with charged He nuclei (He 21 for FRES or RBS, He 31 for NRA), and they require a heavier tracer element to be linked to the diffusing species. Collisions between He nuclei and the heavier element can produce a recoiling of the heavier element (in the case of FRES), backscattering of He 21 nuclei (in the case of RBS), or a nuclear reaction that produces He 41 ions (in the case of NRA).…”

Section: Introductionmentioning

confidence: 99%

“…In the case of FRES, RBS, and NRA, the broadening in the energy values recorded by the detector has been reported as the most important. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] As the energy of the detected nuclei is a function of the depth into the polymer sample, it leads to a broadening in the diffusion coordinate scale. M any authors have used these techniques to study diffusion processes such as transport of small m olecules into glassy polymer m atrices and interpenetration of polymers with different physical properties.…”

Section: Introductionmentioning

confidence: 99%

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True Chemical Composition Profiles at Polymer Interphases: Recovery from Measurements Distorted by Instrumental Broadening

Tomba

Eliçabe

2003

Appl Spectrosc

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The determination of chemical composition profiles at polymer interphases is an important issue at the moment of elucidating the physical mechanisms that operate in polymer diffusion processes and for calculating diffusion parameters. Several techniques are available to measure these profiles, the most common being forward recoil spectroscopy, Rutherford backscattering spectrometry, nuclear reaction analysis, confocal Raman microspectroscopy (CRM), and scanning infrared microscopy. However, all these techniques are affected by the limited resolution of the experimental setup, which in practice produces a rounding effect on the sharp corners of the composition profile; this may lead to incorrect conclusions regarding the measurements. In this work an inverse technique is proposed to correct this undesirable effect in the profiles. The inversion is performed on a model of the measuring process, which includes the instrumental broadening function, a quantitative representation of the limited resolution. The proposed methodology was tested using numerically generated experiments and genuine experimental runs obtained from CRM measurements at interphases of polymer bilayers. In all cases, the recovered profiles were close to the expected ones. In the truly experimental results diffusion tails are observed behind and ahead of the diffusion front before the numerical treatment of the data. These tails may be caused by a genuine mass diffusion or by an artifact. After the numerical treatment the tails disappear and a sharp interphase is recovered, a result one expects for the polymer pairs under study.

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Nuclear reaction analysis: A study on the interface formation in polymer mixtures below the critical point

Cited by 7 publications

References 10 publications

Diblock copolymers attached to homopolymer surfaces and interfaces

Diblock copolymers attached to homopolymer surfaces and interfaces

Diffusion of Poly(dimethylsiloxane) Mixtures with Silicate Nanoparticles

True Chemical Composition Profiles at Polymer Interphases: Recovery from Measurements Distorted by Instrumental Broadening

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