the role of the cross-linking center, and overall enhancement in the mechanical
property of the complete polymer matrix is achieved.
8.4 Recent Updates
8.4.1 Nanofiller Dispersed Polymer Nanocomposites
There are various reports toward the addition of different nanofillers in the polymer
matrix for improving the electrical, thermal, and mechanical properties. Generally,
all nanofiller addition suppresses the crystallinity, and cross-linking alters the polymer chain arrangement. Another effective point is that nanofiller supports salt
dissociation via Lewis acid–base interactions and provides additional conducting
sites for ion transport. But still, there is lack of availability of a polymer matrix with
enhanced amorphous content, and weak polymer–nanofiller interaction results in
nanofiller agglomeration. So, Lin et al. (2015) reported the preparation of (PEO)monodispersed ultrafine SiO 2 (MUSiO 2 ) composite polymer electrolyte
(PEO-MUSiO 2 CPE) via in situ hydrolysis of tetraethyl orthosilicate(TEOS) in
PEO solution. Basically, the advantage with the in situ hydrolysis is that the
polymer–nanofiller interaction is more effective in suppressing the crystallinity by
linking the polymer chains with the nanofiller surface. Two possible dominant
interactions exist here: (i) between the hydroxyl groups at the ends of PEO chains
with the surface of SiO 2 and (ii) wrapping and embedding of PEO chains inside SiO 2
spheres.
TEM image evidences that the higher polymer density was for the in situ prepared
composites as compared to ex situ and indicates the presence of strong interaction
between the polymers and nanofiller (Fig. 8.6 d–f). Further, XRD also evidences the
superior evidence of reduction of crystallinity as compared to the ex situ synthesis
(Fig. 8.6j). Further FTIR and DSC also evidence the reduction of crystallinity by in
situ synthesis. One reason is disruption of the polymer chain reorganization tendency
due to the interaction between MUSiO 2 spheres and polymer chains. Another reason
is improved surface area due to uniformity in size and distribution.
Another remarkable evidence is the increased number of free ion charge carriers
(left to right) in Fig. 8.6k–n. The degree of dissociation of salt was higher for the
sample synthesized by in situ synthesis following the relation in in situ (98.1%) > ex
situ (92.8%) > PEO-fumed SiO 2 CPE (87.4%) > ceramic-free SPE (85.0%). This
was attributed to the simultaneous achievement of two parameters, uniform distribution of SiO 2 and increased the segmental motion of polymer chains. The ionic
conductivity also shows enhancement for polymer electrolyte synthesized by in situ
and is in the range 10
À4
–10
À5 S cm
À1 (at ambient temperature) and 1.2 Â 10
À3 S
cm
À1 (at 60
C). Further, the electrochemical stability window was improved for in
situ synthesis (>5.5 V) as compared to ex situ synthesis (~4.7 V) and may be due to
the strong adsorption effect on anion for in situ synthesis (Park et al. 2003). Further,
the rate capability test of solid-state battery (LFP–CPE–Li) displays double capacity
8 Polymer Nanocomposites: Synthesis and Characterization
281
property of the complete polymer matrix is achieved.
8.4 Recent Updates
8.4.1 Nanofiller Dispersed Polymer Nanocomposites
There are various reports toward the addition of different nanofillers in the polymer
matrix for improving the electrical, thermal, and mechanical properties. Generally,
all nanofiller addition suppresses the crystallinity, and cross-linking alters the polymer chain arrangement. Another effective point is that nanofiller supports salt
dissociation via Lewis acid–base interactions and provides additional conducting
sites for ion transport. But still, there is lack of availability of a polymer matrix with
enhanced amorphous content, and weak polymer–nanofiller interaction results in
nanofiller agglomeration. So, Lin et al. (2015) reported the preparation of (PEO)monodispersed ultrafine SiO 2 (MUSiO 2 ) composite polymer electrolyte
(PEO-MUSiO 2 CPE) via in situ hydrolysis of tetraethyl orthosilicate(TEOS) in
PEO solution. Basically, the advantage with the in situ hydrolysis is that the
polymer–nanofiller interaction is more effective in suppressing the crystallinity by
linking the polymer chains with the nanofiller surface. Two possible dominant
interactions exist here: (i) between the hydroxyl groups at the ends of PEO chains
with the surface of SiO 2 and (ii) wrapping and embedding of PEO chains inside SiO 2
spheres.
TEM image evidences that the higher polymer density was for the in situ prepared
composites as compared to ex situ and indicates the presence of strong interaction
between the polymers and nanofiller (Fig. 8.6 d–f). Further, XRD also evidences the
superior evidence of reduction of crystallinity as compared to the ex situ synthesis
(Fig. 8.6j). Further FTIR and DSC also evidence the reduction of crystallinity by in
situ synthesis. One reason is disruption of the polymer chain reorganization tendency
due to the interaction between MUSiO 2 spheres and polymer chains. Another reason
is improved surface area due to uniformity in size and distribution.
Another remarkable evidence is the increased number of free ion charge carriers
(left to right) in Fig. 8.6k–n. The degree of dissociation of salt was higher for the
sample synthesized by in situ synthesis following the relation in in situ (98.1%) > ex
situ (92.8%) > PEO-fumed SiO 2 CPE (87.4%) > ceramic-free SPE (85.0%). This
was attributed to the simultaneous achievement of two parameters, uniform distribution of SiO 2 and increased the segmental motion of polymer chains. The ionic
conductivity also shows enhancement for polymer electrolyte synthesized by in situ
and is in the range 10
À4
–10
À5 S cm
À1 (at ambient temperature) and 1.2 Â 10
À3 S
cm
À1 (at 60
C). Further, the electrochemical stability window was improved for in
situ synthesis (>5.5 V) as compared to ex situ synthesis (~4.7 V) and may be due to
the strong adsorption effect on anion for in situ synthesis (Park et al. 2003). Further,
the rate capability test of solid-state battery (LFP–CPE–Li) displays double capacity
8 Polymer Nanocomposites: Synthesis and Characterization
281