Tuesday 9 July 2013, Strathblane & Cromdale Halls, 16:30-18:30
Poster session A - Colloids, gels and foams
P.003 Investigation of the shell-hierarchic structures of SiO2 spherical nanoparticles forming the photonic crystals
and photonic glasses
M Arefev1, N Grigoryeva1, K Voronina2, G Kopitsa2 and S Grigoriev2
1
Saint-Petersburg State University, Russia, 2Petersburg Nuclear Physics Institute, Russia
Abstract unavailable
P.004 SANS investigation on self-assembled nanostructured SiO2/TiO2 spheres by evaporation induced selfassembly
J Bahadur, D Sen and S Mazumder
Bhabha Atomic Research Centre, India
Evaporation induced self-assembly of mixed colloids has been employed to synthesize TiO2/SiO2 composite
microspheres. Scanning electron microscopy and small angle neutron scattering experiments reveal hierarchical
morphology of the microspheres. The difference in morphology of the grains for silica, titania and its composite has
been attributed to variation in the average size and polydispersity of the nanoparticles (NPs). The SANS experiments
show that composite grains do not show aging effects in contrast to those of only silica grains and is related to
specific surface area of the grains. The temporal stability of the composite microspheres is attributed to the
inhibition of coalescence of the silica NPs due to presence of titania NPs. Diffraction results show the improved
thermal stability of the composite grains against the anatase to rutile phase transition and is attributed to the
suppression of the growth of titania nanoparticles in silica matrix. A plausible mechanism has been elucidated for
the formation of the microsphere of different morphology during evaporation induced self-assembly. Mesoporous
TiO2/SiO2 grains synthesized by the evaporation driven assembly of the mixed colloids possesses improved
properties and may be utilized as potential candidate for photocatalytic applications.
[1]
[2]
[3]
[4]
Bahadur et al,J. Colloid Interface Sci.351, 2010, 357
Bahadur et al,Langmuir27, 2011, 8404–8414
Bahadur et al, Langmuir, 28, 2012, 1914−1923
Sen, Bahadur et al, Soft Matter, 8, 2012, 1955–1963
P.005 Molecular exchange in block copolymer micelles
S-H Choi1, F Bates2 and T Lodge2
1
Hongik University, Korea, 2University of Minnesota, USA
Block copolymers can self-assemble into micelles when dispersed in a selective solvent. Compared to
thermodynamic structure, much less attention has been paid to the dynamics of molecular exchange in block
copolymer micelles, which underlies the attainment of thermodynamically equilibrated structures. Single molecule
exchange between spherical micelles was investigated using time-resolved small-angle neutron scattering (TRSANS). Two pairs of structurally matched poly(styrene-b-ethylene-alt-propylene) (PS-PEP) compounds were
dispersed in an isotopic squalane mixture, which is highly selective towards the PEP blocks. Each pair includes
polymers with fully deuterated (dPS-PEP) and protonated (hPS-PEP) PS blocks. SANS intensity is directly related to
the concentration of protonated chains in the micelle cores. Therefore, a reduction in the measured scattering
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intensity can be quantitatively correlated with the exchange of chains. The temperature dependence of the chain
exchange rate R(t) can be explained based on the core block dynamics, while the documented quasi-logarithmic
decay of R(t) is shown to be consistent with single chain exchange that is hypersensitive to the core degree of
polymerization and therefore polydispersity. Complementary measurements were also conducted with concentrated
solutions where the micelles pack onto a body-centered cubic lattice. Based on a first-principles model, the
exchange kinetics are expected to be independent of micelle concentration. However, slower dynamics in ordered
micelles were observed. These results suggest that contributions from factors other than core block dynamics can
come into play in the exchange kinetics for ordered micelles.
P.006 Large scale structure of physical hydrogels based on partially hydrophobized hyaluronic acid
A Deriu1, M Di Bari2, C Chiapponi2, I Finelli3, G Paradossi3, L Cantu4, E D Favero4, J Teixeira5 and T Narayanan6
1
Universita' degli Studi di Parma ,Italy, 2Universita' degli studi di Parma, Italy, 3Universita' di Roma,
Italy, 4Universita' degli Studi di Milano, Italy, 5Laboratoire Léon Brillouin, France, 6ESRF, France
Hyaluronic acid (HYA) is a natural polysaccharide able to form a physical gels; it is largely used in biomedicine as
the main component of scaffolds for tissue engineering and as basic material for drug delivery platforms. Chemically
modified forms of HYA have been introduced to produce stiffer gels improving their viscoelastic properties at low
saccharide concentration. Among them, HYADD™ is a chemically modified hyaluronate with 2–3 % of the
carboxylate groups grafted with a hexadecylic amine moiety. Using SAXS SANS, we have performed a comparative
study of the large scale structure of HYA and HYADD gels at concentrations ranging from 0.2 to 10% (w polymer/w
total). For biotechnological applications HYADD gels undergo a thermal annealing process after gelation. In order to
understand the effect of this process on the gel structure, samples with and without annealing have been measured.
The analysis of the diluted samples, i.e. of concentration from 0:3 to 0:8 %, shows that HYADD chains have a rodlike form factor up to a chainlength 80 Å , whereas the chains of the natural polysaccharide maintain this kind of
structure up to 1000Å . In HYADD, the presence of the lateral hexadecylic chains along the backbone induces a
coiling of the polymer: the power law describing the decrease in the scattering intensity as a function of Q (I(Q)
Q1.7), indicates a self avoiding random walk. The behaviour of HYA chains is different: they aggregate in a surface
fractal.
P.007 Detailed SANS contrast variation on toluene-based Co ferrofluid
A Feoktystov1, M Avdeev2, N Matoussevitch3, A Ioffe1 and T Brückel4
1
Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science, Outstation at FRM II, Germany, 2Joint Institute
for Nuclear Research, Frank Laboratory of Neutron Physics, Russia, 3Karlsruher Institut für Technologie, Institut für
Nanotechnologie, Germany, 4Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science and Peter
Grünberg Institut, JARA-FIT, Germany
Contrast variation is a powerful technique, which is widely applied for studies of complex systems in small-angle
neutron scattering experiments. The advantage of H/D substitution in the solvent without change in its chemical
properties makes it possible to study such many-component systems in detail. In case of polydisperse systems one
has to consider averaging of the scattering intensity over the particle size distribution. Thus, the direct modeling of
the scattering intensities requires a certain number of free parameters, which can give the researcher a wrong result.
The new developed approach of contrast variation for polydisperse systems allows researcher to obtain parameters,
which can be later fixed in the model. A successful application of the approach in contrast variation has been
already tested on iron oxide magnetic fluids.
In the present work we report about the contrast variation study of cobalt ferrofluid based on toluene with oleoyl
sarcosine coating. The initial magnetic fluid (1.2 vol. % of Co) was diluted with toluene in the ratio 1:5. Several
contrasts were prepared so that the amount of deuterated toluene in the solvent varied in the range 0-85%. The
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corresponding buffer solutions were prepared and used for background subtraction. Structural parameters of the
nanoparticles were precisely obtained and used for further modeling of the scattering curves.
P.008 Form factor of pNIPAM microgels in overpacked states
U Gasser1, J Hyatt2, J-J Lietor-Santos2, E S Herman2, L Andrew Lyon2 and A Fernandez-Nieves2
1
Paul Scherrer Institut, Switzerland 2Georgia Institute of Technology, USA
We present a form factor study of soft, thermoresponsive microgels based on poly(N- isopropylacrylamide) at high
particle number densities, where the particles must shrink or overlap to fit into the available space. Small-angle
neutron scattering with contrast matching techniques is used to determine the particle form factor. The particle size
is found to be constant up to a volume fraction roughly between random close packing and space filling. Beyond
this point, the particle size decreases with increasing particle concentration; this decrease approximately
corresponds to what is expected in the absence of microgel interpenetration. Noteworthy, we do not observe a glass
transition up to an effective volume fraction of 1.4, as the suspensions remain liquid-like even above space filling.
In addition, shear thinning profiles do not map onto hard sphere behavior, confirming that particle softness is
responsible for our observations.
P.009 Metallo-supramolecular micellar gels: a structural study
A Joset1, C Mugemana2, P Guillet3, M-S Appavou4, N De Souza5, C-A Fustin2, B Leyh1 and J-F Gohy2
1
University of Liège, Belgium, 2Catholic University of Louvain, Belgium, 3Université d’Avignon et des Pays de
Vaucluse, France, 4Jülich Centre for Neutron Science, Germany, 5Australian Nuclear Science and Technology
Organisation, Australia
The formation of metallo-supramolecular micellar gels is investigated by SANS. The micelles consist of polystyreneblock-poly(tert-butylacrylate), PS-b-PtBA-[, (-[ is terpyridine) block copolymers, dissolved in deuterared ethanol,
which guarantees a significant contrast.
The hydrophobic polystyrene core is stabilized by the poly(tert-butylacrylate) corona. The influence of the copolymer
concentration on the micelle structure and on its space organization has been investigated, as well as the significant
rheological impact of the subsequent addition of three metal ions (Fe(II), Ni(II) and Zn(II)).
The form factor of the micelles is described using the Pedersen and Gerstenberg model[1], with a solvent-free
spherical core and gaussian PtBA chains. The fitting parameters are the average radius of the core, the standard
deviation of its size distribution, and the radius of gyration of the PtBA chains.
Upon increasing the copolymer concentration, the average distance between the micelles decreases and
interparticle interferences lead to a structure factor peak at increasing q values. This behaviour has been taken into
account through the Percus-Yevick hard sphere model[2]. Two new parameters are introduced: the hard sphere
interaction distance and the hard sphere volume fraction in the solution.
The structural parameters characterizing both the micelles and the network built upon gelation have been
determined upon increasing concentration and addition of several metal ions. The results are correlated with
dynamic light scattering, electronic microscopy and rheology experiments.
[1]
[2]
Pedersen, J. S.; Gerstenberg, M. C. Macromolecules 1996, 29, 1363-1365
Percus, J. K.; Yevick, G.; J. Phys. Rev 1958, 110, 1-13
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P.010 Structure study of a Microemulsion system with Ionic Liquid
T H Kang, Y Jeon, and M Won Kim
KAIST, Korea
A single phase solution was made with an ionic liquid, 1-tetradecyl-3-methylimidazolium chloride (C14MIM∙Cl)
contained a small amount of water in a non-aqueous liquid, Octane. The solution was transparent optically and very
stable thermodynamically during months. We have used a Small Angle Neutron Scattering (SANS) technique to
investigate the structure of the solution. By fitting data with a guinier plot in the low q range, the radius of gyration of
a microemulsion droplet is 20Å. In the high q region, the power law exponent of intensity curve is below 4, which
indicates a sphere. Since the solution is expected to be a w/o (water in oil) microemulsion, scattering intensity
could be analyzed by fitting with a core-shell model. We have estimated the composition of the core and shell of a
microemulsion droplet by measuring the value of scattering length density (SLD) by a contrast matching method to
reduce the number of fitting parameters. In this presentation, we’ll discuss the SANS data with the core shell model
of three shapes: sphere, oblate and prolate.
P.011 SANS study of nanophase separated hydrogels based on epoxy networks
I Krakovsky1 and N Szekely2
1
Charles University, Czech Republic, 2Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science JCNS,
Germany
Polymer hydrogels are obtained by swelling of hydrophilic polymer networks in water. Small-angle X-ray and neutron
scattering (SAXS/SANS) from polymer networks swollen in good solvents provide an information about frozen and
dynamic heterogeneities, respectively, originating from spatial distribution of network junctions and thermal
movement of polymer segments. However, if the solvent is good for some of network building blocks, only, these
contributions might be superimposed by heterogeneities due to nanophase separation of the system into solventrich and solvent-poor domains.
Hydrogels based on epoxy network are very versatile materials whose properties can be tuned by chemistry,
functionality, and flexibility of the precursors used in their preparation. We have prepared a few series of hydrophilic
epoxy networks by end-linking reaction of α,ω-diamino terminated ABA triblock copolymers of polyoxypropylene
(POP) and polyoxyethylene (POE) with diglycidyl ether of Bisphenol A propoxylate and polypropylene glycol
diglycidyl ether. Epoxy hydrogels were obtained by swelling of these networks to equilibrium in heavy
water. Whereas POE is hydrophilic within the temperature range 0 – 100 oC, POP is hydrophilic at temperatures
lower than ca 15 oC. Consequently, water in hydrogels is not distributed uniformly but gives rise to a temperature
sensitive structure consisting of water-rich and water-poor nanodomains.
In this communication SANS study of structure of polymer hydrogels based on epoxy networks and structural
changes induced by external stimuli will be discussed.
P.012 Effect of doping PVA-borax gels with Holmium salts
M Lawrence1, E Desa2 and V K Aswal3
1
St. Xavier's College, India, 2Department of Physics, Goa University, India, 3Solid State Physics Division, Bhabha
Atomic Research Centre, Mumbai, India
< Poly(Vinyl Alcohol)-borax hydrogels doped with varying concentrations of holmium have been studied using
Small-Angle Neutron Scattering and X-Ray Diffraction. Both techniques point to the attachment of the dopant ions
to the crystallites. The doped gels exhibit higher scattered intensity indicating attachment of the rare-earth complex
to the crystallites through electrostatic attraction. The formation of dopant-crystallite complexes leads to an initial
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increase in correlation length under Ornstein-Zernike approximation. The trends in the SANS data are in keeping
with the variations in the X-ray diffraction patterns pertaining to structures within the PVA chains.
P.013 SANS study of tungsten-potassium two-phase system
A Len1, P Harmat2, G Pépy1 and L Rosta1
1
Wigner Research Center for Physics, Hungary, 2ANTE Innovative Technologies, Hungary
The tungsten filament production and the tungsten structure research have a tradition of many decades in the
lighting industry and a great theoretical importance in the field of material science. However actually the lighting
industry is going through significant changes, the tungsten production continues to be important in many other
industrial sectors as well as in the field of fossil energy, renewable power generation, power transmission and power
distribution. The lighting industry uses the tungsten wires and filaments in incandescent lamps, compact fluorescent
lamps, high intensity discharge lamps etc. Therefore it is worthier to attend the no-answered questions concerning
the tungsten nanoproperties, as it is the question of the relation between the macroscopic properties and the
nanoscale structure of the wires. This paper presents small angle neutron scattering (SANS) studies of tungsten
wires. The obtained results show that the method of SANS, especially the improvement of the two dimensional data
evaluation method, meets it's ''partner'' in the tungsten wires, and gives reasons to state that both, the tungsten
nanostructure research and the SANS method development gain by the joint study of them. We present several
aspects of the nanostructural characteristics of the potassium inclusions in the tungsten wires during the
processing, using the one and two dimensional data evaluation methods, adapted to the complex system of the
oriented scattering objects. The measurements were made on several SANS instruments, namely: D11 Grenoble,
PAXE Saclay and YS Budapest.
P.014 Time-resolved SANS study on reversible light-induced microgel swelling via photosensitive surfactant
S Maccarrone1, Y Zakrevskyy2, V Pipich1, T Schrader1, O Holderer1, S Santer2 and D Richter1
1
JCNS, Germany, 2Universität Potsda, Germany
Stimuli responsive gels have been intensively investigated for applications in biology and medicine as well as in
development of micro-fluidic devices and micro-sensors. These applications are possible thanks to the unique
swelling behavior of hydrogels which can change in response to surrounding conditions (temperature, pH, ionic
strength, solvent). In order to realize remote control of a hydrogel by external stimuli such as light, electric or
magnetic field, a variety of nanoparticles (e.g., silicate, metal, magnetic, or carbon nano-tubes) were incorporated
into polymer networks.
Recently, we have demonstrated a light-induced reversible switching of the swelling of microgel particles triggered
by photo-isomerization of a photosensitive azobenzene-containing surfactant. Addition of the surfactant above a
critical concentration leads to contraction of the microgel. UV-light irradiation results in trans-cis isomerization of the
azobenzene unit incorporated into the surfactant tail and causes an unbinding of the more hydrophilic cis isomer
from the microgel and its reversible swelling.
The hydrogel swelling/contraction is studied for the first time by time-resolved Small Angle Neutron Scattering
(SANS). Experiments are performed on KSW3 instrument at FRMII reactor in Garching bei München. This is the world
only Very Small Angle Neutron Scattering instrument running on the focusing mirror principle and, in standard
configuration, allows structural analysis to length scale up to several micrometers. The structural changes and
reversibly are discussed in terms of intra-/ inter- particles characteristic lengths.
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P.015 Nano-Composite gel composed of Micellar Network and Silica Nano-Particles, as studied by small-angle
scattering
K Mortensen1 and M Annaka2
1
University of Copenhagen, Denmark, 2Kyushu University, Fukuoka, Japan
Organic-inorganic hybrid materials have attracted attention since they can be tailored to combine the advantages of
organic polymers with those of inorganic components yielding materials, possessing enhanced materials properties,
including optical quality. These properties arise from the synergetic interaction of the individual organic and
inorganic constituents. Nature also combines different types of macromolecules in order to form gels with
outstanding physical properties. One example is the lens, which projects the optical image on the retina together
with the cornea. With the attempt to make an artificial composite material with mechanical properties, light
transmission factor and refractive index that makes it suitable for implant of intraocular lens, we have studied a
nano-composite material composed of hydrophobically-modified poly(ethylene glycol) and silica OCAPS nanoparticles [1,2], using combined SANS and SAXS. The structural studies show that the polymers form a micellar
network that order into a bcc phase. The network structure easily aligns into mono or twin-domain texture upon
shear. The OCAPS nano-particles are very well dispersed within the polymer gel structure, as evident from the
combined SANS and SAXS measurements which convincingly show that the OPACS nano-particles are located
within specific regions of the micellar network structure.
[1]
[2]
Annaka, Mortensen, Vigild, Matsuura, Tsuji, Ueda, Tsujinaka Biomacromolecules12, 4011, 2011
Annaka, Mortensen, Matsuura, Ito, Nochioka, Ogata.Soft Matter8, 7185, 2012
P.016 SESANS Experiments using Hard-Sphere Colloids with added Depletants
R Pynn1, A Washington1, X Li1, A Schofield2, K Hong3, R Dalgleish4, M Fitzsimmons5 and Q Wang5
1
Indiana University, USA, 2University of Edinburgh, UK, 3Oak Ridge National Laboratory, USA, 4Rutherford Appleton
Laboratory, UK, 5Los Alamos National Laboratory, USA
A low concentration of macromolecules or small particles added to a colloidal suspension of larger particles causes
an osmotic pressure that tends to drive the large colloidal particles towards each other. We used Spin Echo Small
Angle Scattering (SESANS) to investigate correlations between 200-nm-diameter, sterically-stabilzed, spherical
PMMA particles suspended in a refractive-index-matched solvent when small amounts of polystyrene were added.
SESANS allowed us to clearly separate the short- and long-range correlations. We found that even very small
amounts of polystyrene cause small clusters of PMMA to form. If sufficient polystyrene is added, the small clusters
self-assemble into larger aggregates with power law correlations between PMMA spheres at distances beyond a few
colloidal diameters. When the size of the large aggregates fell within our observation window we were able to
determine the average size of the fractal aggregates. While the separation of short- and long-range correlations
could have been performed using appropriate SANS instrumentation, the two distance scales are more clearly
separated by SESANS. In addition, SESANS permits us to measure the total scattering from the system, a parameter
inaccessible to SANS that can provide important information about the structure of individual particles, without
resorting to contrast matching experiments.
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P.017 Structure and dynamics of responsive core-shell microgels
W Richtering, J Dubbert and C Scherzinger
RWTH Aachen, Germany
Core-shell microgels that consist of different stimuli-senstive polymers reveal unique behaviors due to the coupling
of the two networks. Small angle neutron scattering as well as neutron spin echo experiments provide detailed
information on the mutual influence of core and shell on their swelling. Variation of temperature and / or solvent
composition allows selective swelling or deswelling of core and shell respectively, which influences not only the size
but also the chain dynamics due to confinement and mechanical stress.
In this contribution we will discuss experiments on core-shell microgels with soft and rigid core and also on hollow
microgels exploiting contrast variation. Furthermore the kinetics of microgel collapse was probed by time-resolved
stopped-flow scattering experiments.
P.018 Morphology of carbon nanotubes dispersed in solvents and into polymer and carbon membranes: A SANS
study
A Sapalidis1, E Favvas1, K Stefanopoulos1, S Nitodas2, A Stefopoulos2 and A Mitropoulos3
1
NCSR, Greece, 2Glonatech S.A. TE.S.P.A, Greece, 3Cavala Institute of Technology, Greece
One promising pathway for gas separation and hydrogen production is the membrane separation technology. Best
candidates for this application are inorganic and mostly composite membranes. Carbon nanotubes have been
recognized as ideal reinforcing fillers due to their unique mechanical properties and their high aspect ratio. In this
study, high purity multi-wall carbon nanotubes (MWCNTs) were synthesized using a novel catalytic FBCVD (fluidized
bed chemical vapour deposition) technique, which enables large-scale production at low cost, while maintaining
high purity (> 98%) and exceptional material properties of the developed nanoparticles. Covalent modification of
pristine MWCNTs was applied in order to optimize both the nanoscale morphology and the dispersion in organic
solvents. The functionalization process introduced certain phenol groups, on the external surface of the nanotubes.
The pristine and functionalized carbon MWCNTs were characterized using a variety of techniques such as SEM, TEM,
TGA, XRD, XPS as well as Raman spectroscopy. The composite membranes were produced from the solution
consisted of the functionalized MWCNTs and the polymer (polyimide) and prepared via the wet spinning method
through a specially designed orifice. The as-produced polymeric co-polyimide precursors were further pyrolized,
under controlled conditions, to develop the composite carbon membranes. The information concerning the
agglomeration/dispersion behaviour and the conformation of CNTs both in solutions and within the membrane
matrices was investigated by SANS.
P.019 Effect of polydispersity on the phase behaviour of soft microgel suspensions
A Scotti1, U Gasser1, E Herman2, A Singh2, L Andrew Lyon2, A Fernandez-Nieves2
1
Paul Scherrer Institute, Switzerland, 2Georgia Institute of Technology, USA
Microgel suspensions with a majority of small particles and a small fraction of big particles with about double size
can form crystals without defects caused by the large particles. Due to the softness of microgel particles, the big
particles can shrink to fit into the lattice formed by the small particles [1]. For hard spheres, the size-polydispersity
is a much more limiting factor for crystallization. No hard sphere crystals form at polydispersities higher than 12%.
We systematically study the role of polydispersity in suspensions of fully swollen poly(N-isopropylacrylamide)
(pNIPAM) microgel particles. Small-angle neutron scattering (SANS) and dynamic light scattering are used to
measure polydispersity, particle size and the internal structure of the particles in suspensions with polydispersities
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in the range from 10% up to 20%. We observe crystallization in samples with polydispersity as high as 17%.
Furthermore, the effect of polydispersity on the crystal lattice is obtained from SANS and small-angle X-ray studies.
[1]
A. St. John Iyer and L.A.Lyon, Angew. Chem. Int. Ed. , 48, 4562-4566, 2009
P.020 Water absorption in polyvinyl alcohol cryo-gels under controlled humidity conditions
N K Szekely1, A Radulescu1, L Paduano2 and D Richter3
1
Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science JCNS, Germany, 2Chemistry Department,
University of Naples ,Italy, 3Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science JCNS and Institute
for Complex Systems ICS, Germany
Polyvinyl alcohol (PVA) cryo-gels being nontoxic and non carcinogenic and having bio-adhesive properties are
suitable in a large variety of biotechnological and biomedical applications (e.g. active drug delivery). Because of
their good mechanical properties and high water uptake capacity they could be also used in the treatment of
polluted water.
Physically cross-linked PVA cryo-gels are formed from PVA solution during freeze/thaw thermal cycling and
quenching. Cycling at low temperatures causes formation of ice crystals, which increase the polymer concentration
in the surrounding unfrozen regions, inducing PVA crystallization. This gelation process results in the formation of a
porous network in which polymer crystallites act as junction points. It has been observed that the degree of
crystallinity and the size of crystallites increase with increasing the number of freeze/thaw cycles [1]. Water
absorption properties of PVA cryo-gels might be affected by the number of freeze/thaw cycles in which they have
been produced.
The aim of this study was to reveal the water uptake mechanism of PVA cryo-gels produced in different freeze/thaw
cycles. Structural evolution induced by D2O vapor absorption has been investigated under controlled humidity
conditions by time resolved SANS. Water absorption isotherms have been determined at various relative humidities
(R.H.) and temperatures. PVA cryo-gels showed complex hierarchical structures which were sensitively dependent
on the changes in the R.H.
[1]
R. Ricciardi et al.: Chem. Mater., 2005, 17, 1183-1189
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