Unexpected Elasticity in Assemblies of Glassy Supra-Nanoparticle Clusters

Article abstract of DOI:10.1002/anie.202013361

Granular materials, composed of densely packed particles, are known to possess unique mechanical properties that are highly dependent on the surface structure of the particles. A microscopic understanding of the structure-property relationship in these systems remains unclear. Here, supra-nanoparticle clusters (SNPCs) with precise structures are developed as model systems to elucidate the unexpected elastic behaviors. SNPCs are prepared by coordination-driven assembly of polyhedral oligomeric silsesquioxane (POSS) with metal-organic polyhedron (MOP). Due to the disparity in sizes, the POSS-MOP assemblies, like their classic nanoparticles counterparts, ordering is suppressed, and the POSS-MOP mixtures will vitrify or jam as a function of decreasing temperature. An unexpected elasticity is observed for the SNPC assemblies with a high modulus that is maintained at temperatures far beyond the glass transition temperature. From studies on the dynamics of the hierarchical structures of SNPCs and molecular dynamic simulation, the elasticity has its origins in the interpenetration of POSS-ended arms. The physical molecular interpenetration and inter-locking phenomenon favors the convenient solution or pressing processing of the novel cluster-based elastomers.

Full text of DOI:10.1002/anie.202013361

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
International Edition Chemie
www.angewandte.org
Accepted Article
Title: Unexpected Elasticity in Assemblies of Glassy Supra-
Nanoparticle Clusters
Authors: Thomas P. Russell, Jia-Fu Yin, Zhao Zheng, Junsheng Yang,
Yuchu Liu, Linkun Cai, Qing-Yun Guo, Mu Li, Xinpei Li, Tao
Lin Sun, GengXin Liu, Caili Huang, Stephen Z. D. Cheng, and
Panchao Yin
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.202013361
Link to VoR: https://doi.org/10.1002/anie.202013361

Angewandte Chemie International Edition
10.1002/anie.202013361
RESEARCH ARTICLE
Unexpected Elasticity in Assemblies of Glassy Supra-Nanoparticle
Clusters
[
a]
[a]
[a]
[a]
[a]
[a]
[a]
Jia-Fu Yin, Zhao Zheng, Junsheng Yang, Yuchu Liu, Linkun Cai, Qing-Yun Guo, Mu Li, Xinpei
Li,[a] Tao Lin Sun,[a] GengXin Liu,[d] Caili Huang,[c] Stephen Z. D. Cheng,[a] Thomas P. Russell,*[b] and
Panchao Yin*[a]
[
a]
J. Yin, Z. Zheng, Dr. J. Yang, Y. Liu, L. Cai, Q. Guo, M. Li, Dr. X. Li, Prof. T. Sun, Prof. S. Z. D. Cheng, Prof. P. Yin
South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, State Key Laboratory of
Luminescent Materials and Devices
South China University of Technology
Guangzhou 510640 (China)
E-mail: yinpc@scut.edu.cn, yinpanchao@tsinghua.org.cn
Prof. T. P. Russell
[
b]
Department of Polymer Science and Engineering
University of Massachusetts Amherst
120 Governors Drive, Amherst, MA 01003 (USA)
E-mail: russell@mail.pse.umass.edu
[
[
c]
d]
Prof. C. Huang
Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, School of Chemistry and Chemical Engineering
Huazhong University of Science and Technology
Wuhan 430074 (China)
Prof. G. Liu
Center for Advanced Low-Dimension Materials, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material
Science and Engineering
Donghua University
Shanghai 201620 (China)
Supporting information for this article is given via a link at the end of the document.
Abstract: Granular materials, composed of densely packed particles,
are known to possess unique mechanical properties that are highly
dependent on the surface structure of the particles. A microscopic
understanding of the structure-property relationship in these systems
remains unclear. Here, supra-nanoparticle clusters (SNPCs) with
precise structures are developed as model systems to elucidate the
unexpected elastic behaviors. SNPCs are prepared by coordination-
driven assembly of polyhedral oligomeric silsesquioxane (POSS) with
metal-organic polyhedron (MOP). Due to the disparity in sizes, the
POSS-MOP assemblies, like their classic nanoparticles counterparts,
ordering is suppressed, and the POSS-MOP mixtures will vitrify or jam
as a function of decreasing temperature. An unexpected elasticity is
observed for the SNPC assemblies with a high modulus that is
maintained at temperatures far beyond the glass transition
temperature. From studies on the dynamics of the hierarchical
structures of SNPCs and molecular dynamic simulation, the elasticity
has its origins in the interpenetration of POSS-ended arms. The
physical molecular interpenetration and inter-locking phenomenon
favors the convenient solution or pressing processing of the novel
cluster-based elastomers.
interstitial vacancies, and have elastic plateau moduli that are
tunable.[2] Monolayer assemblies of alkyl-ligand coated
nanoparticles (NPs) exhibit unexpected elasticity, robustness and
resilience at high temperatures, enabling their use in sensors and
device fabrications.[3] Van der Waals interactions can not account
for the strong interactions between the NPs, leaving the
interpenetration and entanglement of the ligands anchored to the
surface of the NPs as the source of this behavior.[ The size
distribution, shape, deformability, and surface functionalization of
the NPs will influence the packing and interactions between
them[2b, 5] and, therefore, their resultant mechanical properties.
Perhaps the most ill-defined of these is the surface
functionalization, where the number of chains grafted to the NP
surface is, at best, an average over all the NPs in the system
based on, for example, gravimetric methods to determine the
relative masses of the NP cores and ligands attached to the
surface. Consequently, developing NPs with precisely defined
surface geometries, surface functionalization, and mechanical
properties is important in quantitatively understanding the packing
of and interactions between NPs, and the roles of shape, including
roughness, and deformability, and the influence of each of these
on the global properties of the assemblies.
4]
Nano-scale molecular clusters (MCs) with precise structures
can be used to generate hierarchical architectures by typical
physical and/or chemical bonding between their surface
Introduction
Complex inter-particle interactions in 2D and 3D colloidal
assemblies give rise to unexpected and often exceptional
mechanical properties.[1] Soft colloids, represented by star
polymers and microgels, can deform and overpack, eliminating
[6]
functional groups. The MCs can be considered as superatoms,
since they are well-defined geometrically with precisely-defined
functionalities that dictate their interactions with the same or
different MCs, and they constitute primary building blocks in the
1
This article is protected by copyright. All rights reserved.

Angewandte Chemie International Edition
10.1002/anie.202013361
RESEARCH ARTICLE
Figure 1. Design strategy for SNPCs derived from the coordination between giant ligands and copper ions to afford materials with different elasticity.
a) Model structure of copper (II) based cuboctahedral MOP core (IPA24-Cu2+24). (b) General strategy for the preparation of VPOSS-MOP, OPOSS-MOP and
OPOSS-MOP-R. (c) Digital photographs of OPOSS-MOP sample which can be processed into thin membrane with certain elasticity and high light transmission.
d) Schematic illustration of the higher degree of interpenetration between OPOSS-MOP to afford homogenous and elastic membrane under high pressure.
(
(
assemblies.[7] By covalently linking MCs with a diverse range of
other NPs, an even larger class of building blocks comprised of
such clusters can be generated.[8] Coordination driven self-
assembly has been widely used to produce complex, well-defined
clusters (e.g. metal-organic polyhedron, MOPs).[9] We used this
approach to construct precise NP clusters based on the
coordination between MC-derived ‘giant-ligands’ (GLs) and metal
ions. A simple self-assembly pathway is proposed to fabricate
supra-NP clusters (SNPCs), where one cuboctahedron core is
surrounded by 24 POSS by the precise coordination of POSS-
based GLs with copper (II) ions (Figure 1). The terminal groups
of GLs are varied to regulate the softness of the coronae of the
clusters, the ability of coronae of different SNPCs to intermix or
entangle, the softness of coronae, i.e. the deformability of the
SNPCs, and, ultimately, the mechanical properties of the SNPC
assemblies. The precise definition of the chemistries and physical
architecture of each SNPC afford the opportunity to provide a
quantitative interpretation of the unique elasticity of the bulk
assemblies that serves as a guide for design of next-generation
cluster-based materials.
The construction of SNPCs is based on the cuboctahedron
MOP assemblies[10] from the coordination between isophthalic
acid (IPA) and Cu . IPA groups are attached to POSS (vinyl-
2+
functionalized POSS, VPOSS; isooctyl-functionalized POSS,
OPOSS) to afford the target GLs and the further coordination with
2
+
Cu leads to the generation of MOP-templated SNPCs (VPOSS-
MOP, OPOSS-MOP and OPOSS-MOP-R; Figure 1; Supporting
Information, Figure S1a, 1b). Due to the coverage of POSS
components onto the surface of MOP, the obtained SNPCs have
similar solubilities as but markedly different sizes than the POSS
precursors, as evidenced by gel permeation chromatography
(GPC) (Figure 2a) and dynamic light scattering (DLS)
(Supporting Information, Figure S1c). The structure of a single
SNPCs in solution was determined by small angle X-ray and
neutron scattering (SAXS and SANS). To analyze the scattering
data, the layers of GLs are divided into two shells adhered to the
MOP cores: the POSS and linker shells (Figure 2b and 2c). The
thicknesses of the shells, determined from fits to the scattering
data, are comparable to the theoretical dimensions of the linker
fragments and POSS. Consequently, OPOSS-MOP (ca. 3.4 nm)
has a larger hydrodynamic radius than VPOSS-MOP (ca. 3.0 nm)
because of the bulky, branched alkyl groups on the POSS
(
Supporting Information, Figure S1c). The core-shell character of
Results and Discussion
the SNPCs is evidenced directly in real space by transmission
electron microscopy (TEM). Contrast in the sphere-like structure
Synthesis and structural characterization of SNPCs
2
This article is protected by copyright. All rights reserved.

Angewandte Chemie International Edition
10.1002/anie.202013361
RESEARCH ARTICLE
with a grey shell and dark core arises from the electronic density
difference between the MOP cores and the outer chain segments
groups that hinder the close packing of OPOSS. One
consequence of this is an enhanced mobility of the OPOSS, as
(
Figure 2d). However, the high mobility of the arm chains leads
indicated by the lower glass transition temperature of pure
o
to the random distributions of them in the outer space of MOP
core, thus contrast is mixed for some SNPCs in the TEM images.
Core-shell structures can be further accessed from the scattering
length density (SLD) distribution and atomic force microscope
OPOSS (T
g
= - 10 C) in comparison to that of VPOSS, with a T
g
above its decomposition temperature.[
11]
Suggested from its
resolved inter-SNPC correlation peak, the high mobility of
OPOSS facilitates the annealing of hierarchical structures in bulk
OPOSS-MOP for homogeneous packing of SNPCs (Supporting
Information, Figure S3).[12]
(
AFM) data (Supporting information, Figure S2).
The deformability and softness of the SNPCs impart a
disordered, glass-like nature to the assemblies. Different from
previous work on crystalline MOPs, the soft GL linkers enable a
deformation of the SNPCs.[13] To quantify the deformability of the
SNPCs, the space occupying ratio (k) of the terminal POSS
groups in the outer shell is determined by: k = (24×VPOSS)/(Vtotal
-
VLf), where VPOSS is the volume of a single POSS, Vtotal denotes
the volume of SNPC sphere, and VLf represents the space
occupied by the MOP core and linker layer. The larger k of
OPOSS-MOP (0.39) in comparison to VPOSS-MOP (0.17) can be
attributed to the bulky isooctyl groups of the OPOSS (Figure 3b;
Supporting Information, Scheme S4 and Table S1). The mobility
of the POSS layer increases with decreasing k and increasing
flexibility of the linker segments, which is also manifest in the
shape and size variations of the SNPCs, as seen in the TEM
image (Figure 2d) and evidenced by the disordered nature of the
bulk materials.
Figure 2. Structural information of the as-prepared SNPCs (VPOSS-MOP,
OPOSS-MOP and OPOSS-MOP-R). (a) GPC traces of the giant precursors
and corresponding SNPCs. (b) and (c) One-dimensional SAXS and SANS
patterns of VPOSS-MOP and OPOSS-MOP in solution and the fitting profiles
based on the core-shell model. (d) TEM image of VPOSS-MOP with a
concentration of 2 mg/L in THF (the core and shell are outlined in red for two
SNPCs); inset is the corresponding structural model of VPOSS-MOP.
The packing of SNPCs for glassy materials
The packing of SNPCs in the bulk, as prepared by a solution
precipitation process, was investigated by small and wide angle
X-ray scattering (SAXS and WAXS) to assess the interpenetration
and deformation of the SNPCs (Figure 3a). Both SNPCs were
amorphous, absent any long-range order even though the
chemical constitution of the each SNPC is exactly the same.
However, the sizes of different SNPCs are not the same, as seen
in the TEM images (Figure 2d) and, also, as indicated by the
scattering data, where the minima in the data are not very sharp,
as would be expected from a sphere scattering function for
monodisperse spheres of the SNPCs. Consequently, the packing
of a polydisperse ensemble of soft particles that could, potentially,
interpenetrate would not be expected to exhibit any long-range
order. The nearest neighbor distance, indicative of a very short-
range order, is evidenced by the intense reflections at qMAX = 0.13
Figure 3. Investigation of the glassy nature and mechanical properties of
SNPCs. (a) SAXS and WAXS patterns of bulk VPOSS-MOP and OPOSS-
MOP. (b) Schematic illustration of the space occupying ratios (k) for different
SNPCs. (c) Stress-strain data for OPOSS-MOP with a strain rate of 1 mm/min.
(d) The packing model we proposed for the bulk OPOSS-MOP, the outer arm
chains are interpenetrated to generate interlocked structures.
-1
Å , corresponding to a SNPC-SNPC center-to-center distance of
.8 nm. This is much smaller than the size of a single SNPCs in
solution and indicates an interpenetration of the GLs of SNPCs.
4
Unique mechanical properties of SNPCs
-1
Maxima are also seen at qMAX = 0.69 Å , corresponding to a
VPOSS-VPOSS center-to-center distance of 0.9 nm, and at qMAX
VPOSS-MOP has a high T
Information, Figure S1d), while OPOSS-MOP has a low T
g
and is a brittle solid (Supporting
(-
g
-1
=
0.52 Å , corresponding to an OPOSS-OPOSS center-to-center
10 °C) from the surface grafted OPOSS clusters (Supporting
distance of 1.2 nm (Figure 3a). The inter-OPOSS reflection is
Information, Figure S4). Interestingly, an elastic-like membrane
broader and less-resolved, due to the bulky, branched alkyl
is formed when
a
powder of OPOSS-MOP, without
3
This article is protected by copyright. All rights reserved.

Angewandte Chemie International Edition
10.1002/anie.202013361
RESEARCH ARTICLE
covalent/supramolecular cross-linking, is extruded at a pressure
of ~ 20 MPa (Figure 1c). The pressed OPOSS-MOP pellet has a
high light transmission, indicative of an optically homogenous
system, indicating an interpenetration of the SNPCs (Supporting
information, Figure S5). The pellet can be elastically bent multiple
times without fracture. Tensile testing shows a linear stress-strain
curve up to 8% strain with a high Young’s modulus (~ 17.42 MPa),
comparable to that of nature rubber[14] and recently developed stiff
elastomers[15] (Figure 3c). After reaching a maximum point (15%
strain), the stress abruptly decreases, characteristic of a brittle
fracture. Supramolecular interactions are absent for the SNPCs
and van der Waals forces cannot account for the elasticity with
such a high Young’s modulus. The strain cycling behaviors of
OPOSS-MOP membrane are also assessed, which reveals the
shape recovery during the cycle tests (Supporting information,
Figure S6). Based on above structural analysis, due to the high
mobility of OPOSS, pressure can facilitate a high degree of
interpenetration of the GLs of different SNPCs, which could
maximally double k to over 50%. Consequently, the kinetic
trapping of the interpenetrated OPOSS in the outer shell of the
SNPCs appears to significantly enhance the mechanical
performance upon deformation and, at a specific strain, the
interpenetration is abruptly released and the material fails (Figure
consistent with our experimental observations, OPOSS-MOP with
shorter linker chains is brittle and OPOSS-MOP with longer linker
chains is in high elastic state (Figure 4; Supporting Information,
Figure S14). The evolution of interface structure also
demonstrates the interpenetrated and inter-locked OPOSS in the
outer shell of the SNPCs is the main cause of the significant
enhancement of the viscoelasticity upon deformation (Supporting
Information, Supplementary movie files).
Dynamics of glassy SNPCs
The unexpected elasticity of the OPOSS-MOP in the bulk
state is correlated with the dynamics of the SNPCs. Three
relaxation processes, α, β and γ, can be observed in the dielectric
loss spectra of OPOSS-MOP (Figure 5a, 5b; Supporting
Information, Figure S10), arising from motions of the SNPCs and
within the SNPCs. Pure OPOSS shows fast relaxation with nearly
constant permittivity (ε’ and ε’’) independent of temperature and
frequency (Supporting Information, Figure S9a, S9b). The
OPOSS segments are expected to be under strong confinement
in the OPOSS-MOP, restraining their intrinsic relaxations
(Supporting Information, Figure S9c, S9d), which could arise
from the interpenetration of the OPOSS-containing arms (Figure
3d). The correlation between the relaxation time and temperature
for the β-relaxation (Supporting Information, Figure S10, green
peaks) of OPOSS-MOP was established through a Vogel-
Fulcher-Tammann (VFT) fitting (Supporting Information, Figure
S11, green plot). Dynamic fragility[16] (m), calculated as 83,
reflects the temperature dependence of the relaxation time near
3
d). The pressure effect is evidenced by the decrease in inter-
SNPC distances at higher pressures (Supporting Information,
Figure S7). Due to the physical nature of the molecular
interpenetration of OPOSS and SNPCs, the SNPC-based
elastomers can be regenerated by solution or pressure
processing routes. The mechanical properties of OPOSS-MOP-R, Tg. In comparison to conventional polymers, OPOSS-MOP shares
which has short, rigid linker components, were also investigated.
OPOSS-MOP-R behaves like a fragile solid with negligible
elasticity after extrusion at high pressure (Supporting Information,
Figure S8). The markedly different behavior of OPOSS-MOP-R
clearly demonstrates the inability of the short, rigid linkers with a
high spacing occupying ratio to interpenetrate, even under high
pressure, leaving the materials brittle.
the same fragility value with poly(ethyl acrylate), but much lower
than polystyrene and polycarbonate with bulky side groups and
polar functional moieties.[ The moderate fragility value may be
associated with the symmetric shape and soft structural units. It
g
17]
should be noted that the value of T from VFT fitting is 266 K,
which is consistent with that measured from DSC (T = 263 K,
g
Supporting Information, Figure S4b).
Figure 4. Molecular dynamics investigation of OPOSS-MOP with different
linker lengths. (a) Molecular structure of OPOSS-MOPs (hydrogen atoms are
omitted here for clarity). (b) and (C) Structure evolution of OPOSS-MOPs with
C
10 linker and C16 linker during the elongation process, which demonstrates
the disparity of their mechanical properties.
To further investigate this unexpected phenomenon, all-atom
non-equilibrium molecular dynamics simulations are performed
on OPOSS-MOP with shorter and longer linker chains systems,
respectively, and elongation flow field is applied for the two
systems. Detailed simulation information has been provided in the
attached SI file. The stress-strain responses of two system are
Figure 5. Dynamic analysis of the structural relaxation for OPOSS-MOP
via different research methods. (a) Temperature dependence of dielectric
loss for OPOSS-MOP at seven selected testing frequency. (b) Broadband
dielectric loss spectra for OPOSS-MOP under different temperatures. (c)
Temperature sweep of OPOSS-MOP with an angle frequency of 10 rad/s. (d)
Master curves for OPOSS-MOP with reference temperature at 30 °C from
SAOS experiments.
4
This article is protected by copyright. All rights reserved.

Angewandte Chemie International Edition
10.1002/anie.202013361
RESEARCH ARTICLE
T
Figure 6. Comprehensive analysis of hierarchical relaxation processes inside SNPCs. (a) Integrated diagram of shifting factors (α ) for different samples and
relaxation time () for multiple relaxation processes. (b) Molecular structures of OPOSS-Vinyl, OPOSS-MOP, OPOSS16 and OPOSS24, the yellow circle represents
individual OPOSS unit. (c) A picture of the hierarchical structure dynamics inside OPOSS-MOP.
Temperature sweep and time-temperature superposition of
small-amplitude oscillatory shear (SAOS) experiments yielded the
dynamic behaviors over a wide temperature and frequency range
(OPOSS+Linker) that are thermally-activated to achieve a more
homogeneous state at higher temperatures. The discrepancy at
low temperature is generated from the existence of
defects/heterogeneities in the interpenetrated region. As the
slowest observable dynamics mode of OPOSS-MOP, the α-
(
Figure 5c, 5d; Supporting Information, Figure S12a). OPOSS-
MOP exhibits a relaxation scaling exponent of 0.6 in the high
frequency region (Figure 5d), indicating segmental dynamics
resulting, more than likely, from the OPOSS.[18] Normally, due to
the weak inter-particle attraction, SNPCs are supposed to gain
mobility to reach the viscous state at the appropriate conditions,
e.g. MOP-templated star polymers of PEG[19] behave as viscous
melts above 40 oC. However, both temperature and frequency
sweeps of OPOSS-MOP indicate that the storage modulus (G’) is
higher than the loss modulus (G’’), suggesting that the SNPC
assembly remains elastic, confirming the interpenetration of the
crowded OPOSS GLs due to the weak temperature and
frequency dependence (Figure 3d). The absence of a rubbery
plateau in the dynamics of OPOSS-MOP indicates that the
contribution of the interpenetration of the SNPCs to the
mechanical performance may be not as strong as other systems
with entanglements[20], and that the disengagement of the SNPC
at a particular level of applied external force is quite sharp (as
evidenced by the mechanical behavior in Figure 3c). The stability
of the OPOSS-MOP after all the mechanical characterizations
was confirmed by GPC (Supporting Information, Figure S13),
where no significant change in the molecular weight was
observed.
a
relaxation (E = 182.5 kJ/mol) is expected to be associated with
the higher order structures of POSS, most likely a cooperative
relaxation of multiple OPOSSs. The α-relaxation shows a T
dependence similar to the rheological dynamics of previously
reported dendrimers of OPOSS, OPOSS16 and OPOSS24, whose
structural units are branching points composed of 2 or 3 OPOSS
clusters that are closely connected (replotted in Figure 6b).[
Therefore, we argue that the α-relaxation of OPOSS-MOP is the
cooperative relaxation of multi-OPOSS units arising from the
interpenetration and inter-locking of the OPOSS-GLs of
neighboring SNPCs.
11]
Conclusion
The cluster-based supramolecular hierarchical structures
define a transition regime between small molecules and colloids,
introducing a new class of materials-by-design. The loose packing
of OPOSS resulting from the branched surface alkyl groups and
the low space occupying ratio of GLs on the MOP surface
promotes deformability of SNPCs and the interpenetration of
OPOSS-GLs. This increases the apparent space occupancy of
OPOSS around the MOPs and locks in the interpenetrated
structures between SNPCs, which contributes to the high elastic
modulus. Moreover, the interpenetrated OPOSSs, though
interlocked, have mobility in the linker zone, providing the origin
of materials’ elasticity. The unique physical interaction renders the
materials with both high processability and high temperature
robustness.
The temperature dependences of the characteristic
relaxation time () and the time-temperature superposition shift
factor (α ) were used to unify the dynamic behaviors resulting
T
from different measurements and different samples containing
OPOSS, so as to develop a clear picture of SNPCs’ hierarchical
dynamics (Figure 6a, 6b, 6c).[21] Interestingly, the γ-relaxation of
a
OPOSS-MOP, with an apparent activation energy (E ) of ~ 37.3
kJ/mol, exhibits similar T dependent dynamics as the rheological
behavior of OPOSS (OPOSS-Vinyl), suggesting that the γ-
relaxation of OPOSS-MOP is correlated with the dynamics of sub-
units (e.g. surface alkyl groups) of a single OPOSS. The β-
In summary, a new type of well-defined core-shell shaped
molecular NPs were prepared by convergence of precise GLs
with traditional MOPs. Scattering in bulk for SNPCs shows a
glassy structures, absent long-range order, arising from the
deformability of outer shell structures. By fine-tuning the surface
relaxation and α
T
of OPOSS-MOP show similar trends at high T
and the relaxation can be attributed to the dynamics of GLs
5
This article is protected by copyright. All rights reserved.

Angewandte Chemie International Edition
10.1002/anie.202013361
RESEARCH ARTICLE
functionality, the dynamics and mechanical properties can be
effectively regulated to obtain significantly different SNPC
materials. Among them, OPOSS-ended SNPCs show
unexpected elasticity and high modulus, absent entanglements or
strong supramolecular interactions between SNPCs. The rational
explanation is a comprehensive result of the inheritance of high
mobility from the OPOSS and the so-facilitated interpenetration
between GLs. The elastomers can be conveniently reprocessed
via solution or pressure processing. Our work uncovers a new
class of materials and opens a new pathway to the design of novel
cluster materials for sensors and device applications with a
specific elasticity, high temperature robustness and facile
regeneration. The protocol can be generally extended to
conventional NPs and colloid systems for improving their
mechanical performances by applying cluster-bearing capping
ligands.
[8]
W.-B. Zhang, X. Yu, C.-L. Wang, H.-J. Sun, I.-F. Hsieh, Y. Li, X.-H. Dong,
K. Yue, R. Van Horn, S. Z. D. Cheng, Macromolecules 2014, 47, 1221-
1239.
[
[
9]
a) D. J. Tranchemontagne, Z. Ni, M. O'Keeffe, O. M. Yaghi, Angew.
Chem. Int. Ed. 2008, 47, 5136-5147; Angew. Chem. 2008, 120, 5214 –
5225; b) R. Chakrabarty, P. S. Mukherjee, P. J. Stang, Chem. Rev. 2011,
111, 6810-6918.
10] M. Zhang, Y. Lai, M. Li, T. Hong, W. Wang, H. Yu, L. Li, Q. Zhou, Y. Ke,
X. Zhan, T. Zhu, C. Huang, P. Yin, Angew. Chem. Int. Ed. 2019, 58,
17412-17417; Angew. Chem. 2019, 131, 17573 – 17578.
[
[
[
11] Y. Liu, G. Liu, W. Zhang, C. Du, C. Wesdemiotis, S. Z. D. Cheng,
Macromolecules 2019, 52, 4341-4348.
12] C. H. Liu, E. M. Janke, R. Li, P. Juhas, O. Gang, D. V. Talapin, S. J. L.
Billinge, J. Appl. Crystallogr. 2020, 53, 699-709.
13] D. J. Clingerman, R. D. Kennedy, J. E. Mondloch, A. A. Sarjeant, J. T.
Hupp, O. K. Farha, C. A. Mirkin, Chem. Commun. 2013, 49, 11485-
11487.
[14] A. I. Medalia, Rubber Chem. Technol. 1978, 51, 437-523.
[
15] a) L. Chen, T. L. Sun, K. Cui, D. R. King, T. Kurokawa, Y. Saruwatari, J.
P. Gong, J. Mater. Chem. A 2019, 7, 17334-17344; b) E. Ducrot, Y. Chen,
M. Bulters, R. P. Sijbesma, C. Creton, Science 2014, 344, 186-189.
16] P. Santangelo, C. Roland, Macromolecules 1998, 31, 4581-4585.
17] Q. Qin, G. B. McKenna, J. Non-cryst Solids. 2006, 352, 2977-2985.
Acknowledgements
[
[
We would like to thank Prof. Rui Zhang for helpful discussion and
the support from China Spallation Neutron Source (CSNS) and
Shanghai Synchrotron Radiation Facility (SSRF) for the access of
SANS and SAXS beamlines (BL-16B and BL-19U). Also, we
acknowledge the Columbia Technology Ventures for providing us
the PDFgetS3 package. P. Y. acknowledges the financial support
from National Key Research and Development Program of China
[18] G. Liu, X. Feng, K. Lang, R. Zhang, D. Guo, S. Yang, S. Z. D. Cheng,
Macromolecules 2017, 50, 6637-6646.
[
[
19] S. S. Nagarkar, M. Tsujimoto, S. Kitagawa, N. Hosono, S. Horike, Chem.
Mater. 2018, 30, 8555-8561.
20] a) C. R. Lꢀpez-Barrꢀn, A. H. Tsou, J. R. Hagadorn, J. A. Throckmorton,
Macromolecules 2018, 51, 6958-6966; b) S. Wasserman, W. Graessley,
J. Rheol. 1992, 36, 543-572.
[21] a) J. Yang, M. Melton, R. Sun, W. Yang, S. Cheng, Macromolecules 2020,
53, 302-311; b) E. J. Bailey, K. I. Winey, Prog. Polym. Sci. 2020, 105,
(
No. 2018YFB0704200), the National Natural Science Foundation
101242.
of China (No.51873067), and Natural Science Foundation of
Guangdong Province (No. 2018A030-313503). G. L. was
supported by the Young Scientists Fund of the National Natural
Science Foundation of China (No. 21903013).
Keywords: Supra-Nanoparticle clusters • well-defined
hierarchical structures • unexpected elasticity • unique dynamic
behaviors
[
1]
a) L. C. Hsiao, R. S. Newman, S. C. Glotzer, M. J. Solomon, Proc. Natl.
Acad. Sci. USA 2012, 109, 16029-16034; b) R. Klajn, K. J. Bishop, M.
Fialkowski, M. Paszewski, C. J. Campbell, T. P. Gray, B. A. Grzybowski,
Science 2007, 316, 261-264; c) D. Lee, S. Jia, S. Banerjee, J. Bevk, I. P.
Herman, J. W. Kysar, Phy. Rev. Lett. 2007, 98, 026103; d) M. Cui, T.
Emrick, T. P. Russell, Science 2013, 342, 460-463.
[
2]
a) L. Gury, M. Gauthier, M. Cloitre, D. Vlassopoulos, Macromolecules
2019, 52, 4617-4623; b) G. M. Conley, P. Aebischer, S. Nöjd, P.
Schurtenberger, F. Scheffold, Sci. Adv. 2017, 3, e1700969; c) M. Asai,
A. Cacciuto, S. K. Kumar, ACS Cent. Sci. 2018, 4, 1179-1184; d) R.
Mangal, S. Srivastava, L. A. Archer, Nat. Commun. 2015, 6, 1-9.
a) J. He, X.-M. Lin, H. Chan, L. Vukovic, P. Král, H. M. Jaeger, Nano Lett.
[
[
3]
4]
2011, 11, 2430-2435; b) K. E. Mueggenburg, X.-M. Lin, R. H. Goldsmith,
H. M. Jaeger, Nat. Mater. 2007, 6, 656.
a) C. R. Bilchak, E. Buenning, M. Asai, K. Zhang, C. J. Durning, S. K.
Kumar, Y. Huang, B. C. Benicewicz, D. W. Gidley, S. Cheng, A. P.
Sokolov, M. Minelli, F. Doghieri, Macromolecules 2017, 50, 7111-7120;
b) G. P. Baeza, C. Dessi, S. Costanzo, D. Zhao, S. Gong, A. Alegria, R.
H. Colby, M. Rubinstein, D. Vlassopoulos, S. K. Kumar, Nat. Commun.
2016, 7, 11368; c) J. Choi, C. M. Hui, J. Pietrasik, H. Dong, K.
Matyjaszewski, M. R. Bockstaller, Soft Matter 2012, 8, 4072.
N. Gnan, E. Zaccarelli, Nat. Phys. 2019, 15, 683-688.
[
[
5]
6]
A. Pinkard, A. M. Champsaur, X. Roy, Acc. Chem. Res. 2018, 51, 919-
929.
[
7]
W.-L. Ong, E. S. O’Brien, P. S. Dougherty, D. W. Paley, C. F. Higgs III,
A. J. McGaughey, J. A. Malen, X. Roy, Nat. Mater. 2017, 16, 83-88.
6
This article is protected by copyright. All rights reserved.

Angewandte Chemie International Edition
10.1002/anie.202013361
RESEARCH ARTICLE
Table of Contents
Unexpected elasticity of SNPCs: Novel supra-nanoparticle clusters (SNPCs) were synthesized by convergence of the metal
organic polyhedron scaffolds with precise giant building blocks. The mechanical properties and structural dynamics can be effectively
regulated by fine-tuning the surface functionalization of the terminal POSS moieties. Unexpected elasticity with high Young’s modulus
of the OPOSS-ended SNPCs was found to be highly correlated with the interpenetration of the neighboring GLs. Our work uncovers
a new class of materials and opens a new pathway to the design of novel cluster materials for sensors and device applications with a
specific elasticity, high temperature robustness and facile regeneration
7
This article is protected by copyright. All rights reserved.