Kyushu Synchrotron Light Research Center（ Form: No.5）

Experiment Report for Prefectural Beamline
Proposal no. : 1304020P
Beamline no.: BL11
Report date: 07/23/2013

Tracking sub-micron assembly in single-domain polymer opals using
small angle x-ray scattering
Qibin Zhao 1 and Jeremy Baumberg 1
University of Cambridge, UK
Katsuhiko Saito 2 and Qixin Guo 2
Saga University, Japan※１Long term users of Advanced Research User Proposals are requested to submit thisreport corresponding to each research term (I), (II), or (III), specifying each researchterm at the end of the Report Title.

※2

Users of Non-proprietary proposals (Public User Proposal, Advanced Research User
Proposal with exception of both Trial Course and Industry-Academia Collaboration
Course, and Frontier Research User Proposal) are also requested to publish their resultsin the form of a refereed journal article or to submit their results in the form of aSAGA-LS Research Report refereed by SAGA-LS within two years from the end of thecurrent fiscal year．

1. Summary

Single and multiple components polymer opals are 3D photonic crystals
which are comprised of densely packed core-shell spheres. By using small
angle x-ray diffraction technique, our experiment provides strong evidenceof the effectiveness of the shear ordering process for polymer opals.
Moreover, the experimental results enable us to gain insight into how
random packed multi-component polymer opals system develops into
highly ordered photonic crystal structures.

２．Purposeof experiment and background
２．

Polymer opals are novel stretchable 3D photonic crystals comprised of denselypacked core-shell spheres [1-3]. The spheres, with a hard polystyrene core and a low
glass transition soft PEA shell, are pressed into thin films and sheared in solid phasewithout using any liquid solvent. By using small angle x-ray diffraction technique,the goal of the experiment is expected to be in two aspects: the first is to investigate
the arrangement of the nanospheres in binary and ternary polymer opal films after
shear ordering, and the second is to clarify the puzzles from our previous SAXS
experiment on single component polymer opals, including peculiar intensity

distribution along the tubes and large intensity contrast between spots at the same
Q range. The experiment is supposed to be able to provide valuable information onordered as well as disordered structures within the films, which therefore promises a
deeper look on how spheres of either the same size or different sizes rearrange undershearing force in highly viscoelastic medium.
Compared to most of the top-down methods
which are time costing and expensive,
bottom-up assembly seems to be more
promising and commonly used for fabricating
low cost industrial applicable 3D photonic
crystals. However, due to the intrinsic
properties of the method, the existence of
Figure 1. Dark-field spectra of polymer-opal
disordered structures is always a serious
films show improving order with BIOS
problem, which is detrimental for the opticalprocess.
performance and the potential applications.
Shearing technique has been used for improving the order of self-assemblied
colloidal structures, however, for those systems, viscosity of the medium is usuallylow, and shearing is done in liquid phase. Different from most of the colloidal
systems, our efforts in recent years on making well-ordered polymeric opaline
photonic crystals [4-11] show how shearing works in highly viscoelastic medium insolid phase. By using shearing force, we have fabricated industrial scale (>100m)
flexible photonic crystal films which exhibit strong structural colours uniformly overlarge areas. Since optical properties of the film comes from the interplay of order anddisorders of the structure, understanding how the spheres are arranged in bulk is ofgreat importance for both science and applications [3,4,8,11]. However, due to thesmall size of the spheres (~200nm) as well as the low electron density contrastbetween the spheres and the medium, it has been a great challenge to characterize
the structure. The setup of small angle x-ray diffraction in Saga provides very highresolution and intensity which facilitates the characterization of structures insubmicron scale, which is a perfect technique for our polymer opal system.
３．Experimental（Note:Description of sample，method of experiment and analysis, etc.）
３．

Figure 1. SAXS patterns of samples
before and after shear ordering. a,before sheaing,b, biaxial shearing 5
passes, c, biaxial shearing 20 passes,d, uniaxial shearing five passes, e,uniaxial shearing 20 passes. Beamnormal to the (001) plane.

The measurements are performed using
the photon energy of 8.2 keV and a Rigaku
high resolution detector. The radius of thebeam stop is just at the edge of an
acceptable level for imaging the reciprocal
space lattices, which gives us as muchinformation as we want but at the sametime generated some distortions over thediffraction patterns.
Polymer opal films with different degrees
of structural order as well as different
ordering
techniques
havebeencharacterized. Clear SAXS patterns were observed on both single component andmulti-component polymer opals which are comprised of pure polymeric spheres
embedded in medium of a different polymer with very low electronic density contrast
between them.

４．Results
and Discussions
４．

The results show that before applying theordering process, the structure of the film
is completely disordered (Fig 1a) but doshow pronounced rings presumably
originating from (short-range) positional
Figure 2. SAXS patterns of binary
polymer opals. a&b, R/G binary opal
before and after ordering, c&d, B/Gbinary opal before and after ordering,e&f, B/R binary opal before and afterordering. Beam normal to the (001)plane.

Figure 3. SAXS patterns of ternary
polymer opals. a&b, R/G/B 1:1:1
ternary opal before and after ordering,
c&d, R/G/B 3:2:1 ternary opal before
and after ordering, e&f, R/G/B 1:2:3
ternary opal before and after ordering.
Beam normal to the (001) plane.

correlations
betweenthepositions. Clear crystalline

particlefeaturesappear after applying the ordering
process, then these features become more
and more significant with increasing
number of the ordering passes (Fig 1b-1e)
which indicate better structural orderand alignment. Shearing process shows
the same effect on both binary andternary polymer opals (Figure 2, 3).
Careful analysis of the data will help us
understand more about how the spheres
rearrange from jammed state to
crystalline structure under shearing force
with extremely large polydispersity.
Preliminary analysis of the results of theexperiment provides strong evidence ofthe effectiveness of the shear ordering
process for polymer opals. Meantime, theinformation enables us to gain insight
into
howrandom
packedmulti-component polymer opals systemdevelops into highly ordered photonic
crystal structures.

５．Future
issues５．

1. Characterization of inter-plane structural order by aligning the beam parallelto the planes
2. Tilting the samples in different orientations in order to get more information

of the 3D reciprocal lattice strucuture
3. Obtaining the form factor of core-shell spheres from experiments by using
very dilute suspensions

６．References
６．

[1] O.L.J. Pursianinen, J.J. Baumberg, et al., Opt. Exp. 15, 9553 (2007).
[2] T. Ruhl, P. Spahn, G.P. Hellmann, Polymer 44, 7625 (2003).
[3] O.L.J. Pursianinen, J.J. Baumberg, et al., Advanced Materials 20, 1484 (2008).
[4] A.I. Haines, C.E. Finlayson, et al., Advanced Materials 24, 305 (2012).
[5] J.J. Baumberg, O.L. Pursiainen, et al., Phys. Rev. B 80, 201103(R) (2009)[6] D.R.E Snoswell, J.J. Baumberg, Textiles 36, 8 (2009)[7] A. Kontogeorgos, J.J. Baumberg, et al, Phys. Rev. Lett. 105, 233909 (2010)[8] M. Kolle, B. Zheng, N. Gibbons, J.J. Baumberg, U, Steiner, Opt. Exp. 18, 4356
(2010)[9] D.R.E. Snoswell, A. Kontogeorgos, J.J. Baumberg, et al., Phys. Rev. E 81,020401(R) (2010)[10] C.E. Finlayson,.. J.J. Baumberg, Adv. Mat. (2011);[11] C.E. Finlayson, …, J.J. Baumberg, Opt. Exp. 19, 3144 .(2011)[12] A.V. Petukhov et al., Journal of Applied Crystallography 39, 137 (2006).
[13] J.H.J. Thijssen, A.V. Petukhov, D.C. ’t Hart et al., Adv. Mater. 18, 1662–1666 (2006).

７．Publications,patents（Note: Typical deliverables related to this proposal．）
７．

The experimental data obtained in this work will be submitted to an international
scientific journal.
８．Keywords（Note:2-3 words about samples and experimental methods．）
８．

Polymer opals, SAXS, Shearing, Order and disorders
９．About
the publication of research results
９．
Please delete either item ① or item ② indicated below, according to a user’s choice of publications as
described in ※2. Also, please fill in an expected date of publication of a refereed journal article or anexpected date of submission of a SAGA-LS Research Report. For example, deadline of both publications
corresponding to the proposals performed in the fiscal 2013 is by the end of fiscal 2015 in both ① and②.
① Publication of a refereed journal article(the date of publication：2015）