Since then, tremendous research is done using polymers such as modified PAA,
P4VP, polyvinyl phenol, PEO, polysiloxanes with benzoic acid moiety, and surfactants such as phenols, aliphatic amines, stilbazoles, mesogenic biphenyl with a
carboxylic group at one end etc. These complexes resulted in Sm, N phases even
though the constituent molecules exhibited no LC behavior. Using PVP and pentadecyl phenols and carboxylic acids, Ruokilainen et al. demonstrated that two factors
have substantial influence on the formation of these mesomorphic structures: first,
the strength of the bonding between the polymer and the surfactant and second
stronger polar-nonpolar interactions between the two (Ruokolainen et al. 1996). By
introducing such polymer/moiety complexes as one of the BCP blocks, hierarchical
structure-in-structure morphologies have been achieved. These systems are also
termed as comb-coil BCPs because the amphiphilic molecules form a comb-like
architecture with the polymer backbone. The small M n amphiphilic molecule
behaves like a plasticizer or high boiling point solvent in the system. Designing
supramolecular dynamic and functional materials based on these weaker bonds is an
attractive area of research because of the ease with which complex architectures can
be formed and deformed as necessary. Using solvent extraction, the small molar
mass moiety can also be dissolved, leading to the formation of nanoporous films
(Fahmi et al. 2003). Deposition of metals in such nanopores leads to the formation of
arrays of nanodots and nanowires (Sidorenko et al. 2003). Valkama et al. studied the
phase behavior of PS-b-PVP BCP with two interactions: first the PVP block is
associated to 3-pentadecyl phenol using H-bond and in the second, the pyridine is
protonated with methanesulfonic acid (MSA) and then the MSA is H-bonded to PDP
(Valkama et al. 2002, 2004, 2003a, b, 2006). The phenol group of the PDP molecules
forms H-bonds with the PVP or the protonated PVP and forms a supramolecular
comb-like architecture. Although most of the PDP stays in the PVP domains, the
authors reported that about 5% by weight is soluble in PS at RT. The authors
investigated the phase structures of both the systems as a function of w (weight
fraction) of comb and as a function of temperature using FTIR, X-ray scattering, and
TEM experiments and constructed a morphology diagram as shown in Fig. 18b. Due
to the hierarchy of length scales involved in the self-assembly, unique structure-instructure architectures were observed in all the samples. BCP self-organization
occurs at 10–100 nm length scale while the PDP organization occurs at 1–5 nm
length scale. In the H-bonded PS-PVP/PDP system with varying weight fractions of
comb block from 0.03 to0.92, the authors observed L-in-S, L-in-C, L-in-HPL, L-inL where the first letter refers to the morphology within the P4VP-PDP domain
(1–5 nm) while the second letter represents the overall BCP morphology
(10–100 nm). At T = 60
C, the authors observed ODT in P4VP-PDP domains
due to the weakening of the H-bonds and at T = 120
C, PDP becomes soluble in
PS. This leads to a transformation of the morphology of the system via OOTs. The
authors report a number of such OOTs that highlight the uniqueness of their system
as compared to a coil-coil system. This comb-coil system can be considered as a
BCP system in the presence of a solvent. As the temperature changes, the PDP
becomes soluble in PS thereby inducing OOTs. Similar structure-in-structure phase
morphologies were also observed in protonated P4VP and PDP H-bonded samples at
206
K. K. Tenneti et al.
P4VP, polyvinyl phenol, PEO, polysiloxanes with benzoic acid moiety, and surfactants such as phenols, aliphatic amines, stilbazoles, mesogenic biphenyl with a
carboxylic group at one end etc. These complexes resulted in Sm, N phases even
though the constituent molecules exhibited no LC behavior. Using PVP and pentadecyl phenols and carboxylic acids, Ruokilainen et al. demonstrated that two factors
have substantial influence on the formation of these mesomorphic structures: first,
the strength of the bonding between the polymer and the surfactant and second
stronger polar-nonpolar interactions between the two (Ruokolainen et al. 1996). By
introducing such polymer/moiety complexes as one of the BCP blocks, hierarchical
structure-in-structure morphologies have been achieved. These systems are also
termed as comb-coil BCPs because the amphiphilic molecules form a comb-like
architecture with the polymer backbone. The small M n amphiphilic molecule
behaves like a plasticizer or high boiling point solvent in the system. Designing
supramolecular dynamic and functional materials based on these weaker bonds is an
attractive area of research because of the ease with which complex architectures can
be formed and deformed as necessary. Using solvent extraction, the small molar
mass moiety can also be dissolved, leading to the formation of nanoporous films
(Fahmi et al. 2003). Deposition of metals in such nanopores leads to the formation of
arrays of nanodots and nanowires (Sidorenko et al. 2003). Valkama et al. studied the
phase behavior of PS-b-PVP BCP with two interactions: first the PVP block is
associated to 3-pentadecyl phenol using H-bond and in the second, the pyridine is
protonated with methanesulfonic acid (MSA) and then the MSA is H-bonded to PDP
(Valkama et al. 2002, 2004, 2003a, b, 2006). The phenol group of the PDP molecules
forms H-bonds with the PVP or the protonated PVP and forms a supramolecular
comb-like architecture. Although most of the PDP stays in the PVP domains, the
authors reported that about 5% by weight is soluble in PS at RT. The authors
investigated the phase structures of both the systems as a function of w (weight
fraction) of comb and as a function of temperature using FTIR, X-ray scattering, and
TEM experiments and constructed a morphology diagram as shown in Fig. 18b. Due
to the hierarchy of length scales involved in the self-assembly, unique structure-instructure architectures were observed in all the samples. BCP self-organization
occurs at 10–100 nm length scale while the PDP organization occurs at 1–5 nm
length scale. In the H-bonded PS-PVP/PDP system with varying weight fractions of
comb block from 0.03 to0.92, the authors observed L-in-S, L-in-C, L-in-HPL, L-inL where the first letter refers to the morphology within the P4VP-PDP domain
(1–5 nm) while the second letter represents the overall BCP morphology
(10–100 nm). At T = 60
C, the authors observed ODT in P4VP-PDP domains
due to the weakening of the H-bonds and at T = 120
C, PDP becomes soluble in
PS. This leads to a transformation of the morphology of the system via OOTs. The
authors report a number of such OOTs that highlight the uniqueness of their system
as compared to a coil-coil system. This comb-coil system can be considered as a
BCP system in the presence of a solvent. As the temperature changes, the PDP
becomes soluble in PS thereby inducing OOTs. Similar structure-in-structure phase
morphologies were also observed in protonated P4VP and PDP H-bonded samples at
206
K. K. Tenneti et al.