The highly asymmetric lamellar (A-LAM) nanostructure is one of the most important template geometries for block copolymer (BCP) lithography. However, A-LAM is unattainable from conventional BCPs, and ...there is no general molecular design strategy for A-LAM-forming BCP. Herein, a nanoparticle-linear hybrid BCP system is reported, which is designed based on the intramolecular crosslinking technique, as a remarkably effective platform to obtain the A-LAM morphology. The hybrid BCPs consisting of polystyrene single-chain nanoparticles and linear polylactide segments show a remarkable capability to form the A-LAM morphology in bulk, where a maximum width ratio of 4.1 between the two domains is obtained. This unusual phase behavior is attributed to the bulky and rigid characteristics of the nanoparticle block. Furthermore, the thin films of these hybrid BCPs show perpendicularly oriented A-LAM morphology on a chemically modified Si substrate, allowing promising application in the fabrication of asymmetric line-and-space nanopatterns.
The compositionally asymmetric nanoparticle-linear hybrid block copolymers with a polystyrene single-chain nanoparticle and a long linear polylactide demonstrated the astonishing capability to produce the highly asymmetric lamellar nanostructures.
A novel strategy for downsizing the feature of microphase-separated structures was developed
the intramolecular crosslinking reaction of block copolymers (BCPs) without changing the molecular weight. ...A series of BCPs consisting of polystyrene-
-(
-3-butenyl styrene) and poly(
-lactide) (SBS-LA) was subjected to Ru-catalyzed olefin metathesis under highly diluted conditions to produce intramolecularly crosslinked BCPs (SBS(
)-LAs). Small-angle X-ray scattering measurement and transmission electron microscopy observation of the SBS(
)-LAs revealed feature size reduction in lamellar (LAM) and hexagonally close-packed cylinder (HEX) structures in the bulk state, which was surely due to the restricted chain dimensions of the intramolecularly crosslinked SBS block. Notably, the degree of size reduction was controllable by varying the crosslink density, with a maximum decrease of 22% in the LAM spacing. In addition, we successfully observed the downsizing of the HEX structure in the thin film state using atomic force microscopy, indicating the applicability of the present methodology to next-generation lithography technology.
Developing an efficient and versatile process to transform a single linear polymer chain into a shape‐defined nanoobject is a major challenge in the fields of chemistry and nanotechnology to ...replicate sophisticated biological functions of proteins and nucleic acids in a synthetic polymer system. In this study, we performed one‐shot intrablock cross‐linking of linear block copolymers (BCPs) to realize single‐chain nanoparticles (SCNPs) with two chemically compartmentalized domains (Janus‐shaped SCNPs). Detailed structural characterizations of the Janus‐shaped SCNP composed of polystyrene‐block‐poly(glycolic acid) revealed its compactly folded conformation and compartmentalized block localization, similar to the self‐folded tertiary structures of natural proteins. Versatility of the one‐shot intrablock cross‐linking was demonstrated using several different BCP precursors. In addition, the Janus‐shaped SCNP produce miniscule microphase‐separated structures.
A one‐shot intrablock cross‐linking protocol was demonstrated to achieve a rapid and facile synthesis of single‐chain nanoparticles (SCNPs) with two chemically compartmentalized domains (Janus‐shaped SCNPs) from the various diblock copolymers bearing one particular cross‐linkable functionality across the entire polymer chain. Janus‐shaped SCNP produce significantly small microphase‐separated structure.
Block copolymers (BCPs) with a high Flory–Huggins interaction parameter ( χ ) and a low degree of polymerization ( N ) are being investigated to create microphase-separated structures with sub-10 nm ...periodicity ( d ). However, the lowered N value also leads to undesirable properties. In this paper, we demonstrate that the use of a star-block architecture is an effective way to achieve microphase separation with sub-10 nm d without reducing the molecular weight. Thus, three-, four-, and six-armed star-block copolymers consisting of poly(ε-caprolactone) (PCL) and maltotriose (MT), i.e. , (PCL- b -MT) x ( x = 3, 4, and 6, respectively), with comparable arm lengths and MT volume fractions were synthesized in three steps involving the ring-opening polymerization of ε-caprolactone, chain end modification, and click reaction. Small angle X-ray scattering experiments revealed that the (PCL- b -MT) x microphase separated into hexagonally close-packed cylindrical structures with a d of 6–8 nm. The d value and morphology of (PCL- b -MT) x are essentially the same as those of the corresponding arm unit, i.e. , linear diblock copolymers (PCL- b -MTs). In other words, the d value can be fixed at less than 10 nm even though the total molecular weight of the BCP is increased by increasing the arm number. In addition, (PCL- b -MT) x had the advantages of an increased order–disorder transition temperature as well as better quality of the nanostructure formed in the thin film state compared to PCL- b -MT. Overall, well-ordered microphase-separated structures with a d value less than 10 nm were obtained, while the total molecular weight of the BCPs is higher than 10 000 g mol −1 .
Pd-lactate (LA)-co-3-hydroxybutyrate (3HB) is an artificial polyhydroxyalkanoate (PHA) containing unusual d-LA units. In this study, the P(d-LA-co-3HB)-degrading bacterial group in the soil was ...analyzed and the bacterial degradation of the d-LA clustering structure in the copolymer were evaluated by using chemically synthetic d-LA homo-oligomers. A total of 216 soil samples were screened on the basis of clear zone formation on agar plates containing emulsified P(64 mol% d-LA-co-3HB). The 16S rRNA analysis of the isolated bacteria resulted in the identification of eight Variovorax, three Acidovorax, and one Burkholderia strains, which are closely related to previously identified natural PHA-degrading bacteria. These bacteria nearly consumed the P(d-LA-co-3HB) emulsion in the liquid culture; however, a small amount of the d-LA fraction remained unconsumed, which should be attributable to the d-LA-clustering structure in the copolymer. Cultivation of the isolated bacteria with the d-LA homo-oligomers revealed that the oligomers with a degree of polymerization (DP) ranging from 10 to 30 were partly consumed by six Variovorax and one Acidovorax strains. In contrast, the oligomers with DP ranging from 20 to 60 were not consumed by the isolated bacteria. These results indicate that d-LA homo-oligomers with DP higher than approximately 20 are hardly degraded by the soil bacteria. Molecular dynamic simulation of the d-LA homo-oligomers indicated that the upper limit of DP is likely to be determined by the conformational structure of the oligomers in water. The information obtained in this study will be useful for the molecular design of biodegradable d-LA-containing polymers.
•11 P(d-lactate-co-3-hydroxybutyrate)-degrading soil bacteria were isolated.•d-LA homo-oligomers with approx. DP ≥ 20 were not consumed by the isolates.•The conformations of d-LA homo-oligomers were estimated by MD simulation.
A novel strategy for downsizing the feature of microphase-separated structures was developed
via
the intramolecular crosslinking reaction of block copolymers (BCPs) without changing the molecular ...weight. A series of BCPs consisting of polystyrene-
st
-(
p
-3-butenyl styrene) and poly(
rac
-lactide) (SBS-LA) was subjected to Ru-catalyzed olefin metathesis under highly diluted conditions to produce intramolecularly crosslinked BCPs (SBS(
cl
)-LAs). Small-angle X-ray scattering measurement and transmission electron microscopy observation of the SBS(
cl
)-LAs revealed feature size reduction in lamellar (LAM) and hexagonally close-packed cylinder (HEX) structures in the bulk state, which was surely due to the restricted chain dimensions of the intramolecularly crosslinked SBS block. Notably, the degree of size reduction was controllable by varying the crosslink density, with a maximum decrease of 22% in the LAM spacing. In addition, we successfully observed the downsizing of the HEX structure in the thin film state using atomic force microscopy, indicating the applicability of the present methodology to next-generation lithography technology.
Intramolecular crosslinking of block copolymers was established as a novel strategy for downsizing the microphase-separated structures without changing the molecular weight.
Intramolecular crosslinking of block copolymers was established as a novel strategy for downsizing the microphase-separated structures without changing the molecular weight.
A novel strategy for ...downsizing the feature of microphase-separated structures was developed
via
the intramolecular crosslinking reaction of block copolymers (BCPs) without changing the molecular weight. A series of BCPs consisting of polystyrene-
st
-(
p
-3-butenyl styrene) and poly(
rac
-lactide) (SBS–LA) was subjected to Ru-catalyzed olefin metathesis under highly diluted conditions to produce intramolecularly crosslinked BCPs (SBS(
cl
)–LAs). Small-angle X-ray scattering measurement and transmission electron microscopy observation of the SBS(
cl
)–LAs revealed feature size reduction in lamellar (LAM) and hexagonally close-packed cylinder (HEX) structures in the bulk state, which was surely due to the restricted chain dimensions of the intramolecularly crosslinked SBS block. Notably, the degree of size reduction was controllable by varying the crosslink density, with a maximum decrease of 22% in the LAM spacing. In addition, we successfully observed the downsizing of the HEX structure in the thin film state using atomic force microscopy, indicating the applicability of the present methodology to next-generation lithography technology.
The effect of intramolecular cross-linking in an amphiphilic block copolymer (BCP) system was systematically investigated in terms of its thermal properties, critical micelle concentration (CMC), and ...aqueous self-assembly. A series of linear BCPs consisting of poly(ethylene glycol) (PEG) as a hydrophilic block and poly( -caprolactone-
co
-7-allyloxepan-2-one) (P(CL-
co
-ACL)) as a hydrophobic block were prepared by the ring-opening copolymerization of -caprolactone (CL) and 7-allyloxepan-2-one (ACL) using poly(ethylene glycol)monomethyl ether as an initiator. The intramolecular olefin metathesis reaction in the P(CL-
co
-ACL) block was subsequently carried out under various conditions to prepare the cross-linked BCPs with different degrees of cross-linking. The thermal analysis confirmed that the linear P(CL-
co
-ACL) block was found to crystallize, while the cross-linked one showed no crystallinity. In addition, glass transition temperature of the P(CL-
co
-ACL) block increased upon cross-linking. On the other hand, the intramolecular cross-linking had no significant influence on the CMC. The self-assembled micelles were prepared from the obtained BCPs and their size and morphology were investigated. For the BCPs with relatively short PEG chains, the micellar size decreased from 36.6 nm to 16.7 nm as the degree of cross-linking of the P(CL-
co
-ACL) block increased. On the other hand, the BCPs with relatively long PEG chains showed a change in the micellar morphology from spherical micelles to short worm and large compound micelles upon cross-linking.
The effect of intramolecular cross-linking on aqueous self-assembly behavior was systematically investigated based on an amphiphilic block copolymer system.
Block copolymers (BCPs) with a high Flory-Huggins interaction parameter (
χ
) and a low degree of polymerization (
N
) are being investigated to create microphase-separated structures with sub-10 nm ...periodicity (
d
). However, the lowered
N
value also leads to undesirable properties. In this paper, we demonstrate that the use of a star-block architecture is an effective way to achieve microphase separation with sub-10 nm
d
without reducing the molecular weight. Thus, three-, four-, and six-armed star-block copolymers consisting of poly( -caprolactone) (PCL) and maltotriose (MT),
i.e.
, (PCL-
b
-MT)
x
(
x
= 3, 4, and 6, respectively), with comparable arm lengths and MT volume fractions were synthesized in three steps involving the ring-opening polymerization of -caprolactone, chain end modification, and click reaction. Small angle X-ray scattering experiments revealed that the (PCL-
b
-MT)
x
microphase separated into hexagonally close-packed cylindrical structures with a
d
of 6-8 nm. The
d
value and morphology of (PCL-
b
-MT)
x
are essentially the same as those of the corresponding arm unit,
i.e.
, linear diblock copolymers (PCL-
b
-MTs). In other words, the
d
value can be fixed at less than 10 nm even though the total molecular weight of the BCP is increased by increasing the arm number. In addition, (PCL-
b
-MT)
x
had the advantages of an increased order-disorder transition temperature as well as better quality of the nanostructure formed in the thin film state compared to PCL-
b
-MT. Overall, well-ordered microphase-separated structures with a
d
value less than 10 nm were obtained, while the total molecular weight of the BCPs is higher than 10 000 g mol
−1
.
Star-block copolymers consisting of polycaprolactone and maltotriose segments with three, four, and six arms were synthesized to achieve sub-10 nm microphase-separated structures.
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