Design guide of amphiphilic crystalline random copolymers for sub-10 nm microphase separation

Ikami, Takaya; Kimura, Yoshihiko; Takenaka, Mikihito; Ouchi, Makoto; Terashima, Takaya

doi:10.1039/d0py01618g

Cited by 14 publications

(21 citation statements)

References 50 publications

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“…So far, polymeric lamellar-structured materials have been prepared using crystalline polymers, 12 , 13 liquid crystalline polymers, 14 − 17 and block copolymers, 18 − 20 while reports using amorphous homo- and copolymers remain scarce. 21 , 22 In this context, we have discovered that a series of amorphous homo- and copolymers of alkyl acrylate and alkyl acrylamide form uniaxially oriented lamellar structures via annealing above their glass-transition temperatures ( T g ) under humid conditions (humid annealing). 23 − 28 During the humid annealing, water molecules adsorb on the hydrophilic amide and ester groups due to the highly humid conditions.…”

Section: Introductionmentioning

confidence: 99%

Self-Assembly and -Cross-Linking Lamellar Films by Nanophase Separation with Solvent-Induced Anisotropic Structural Changes

et al. 2022

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In this study, we have prepared thermally and chemically stable lamellar polymer films via humid annealing. The amphiphilic polymer poly( N -dodecyl acrylamide- stat -3-(trimethoxysilyl)propyl acrylate) [p(DDA/TMSPA)] forms a self-assembled lamellar structure via annealing at 60 °C under 98% relative humidity (humid annealing) due to nanophase separation between the hydrophobic dodecyl side and main chains with the amide groups that contain adsorbed water. Moreover, a self-cross-linking reaction of TMSPA proceeds during the humid annealing. As a result, the lamellar films maintain their structure even when annealed above their glass-transition temperature. On the other hand, the films swell when immersed in toluene. The highly ordered lamellar structure collapses due to the swelling but can be re-established by subsequent humid annealing. A multilayer freestanding film can be exfoliated via sonication in toluene. The exfoliated multilayer films initially form a dome-shaped structure, which is converted to a plate-shaped structure upon humid annealing. In their entirety, these results reveal that the molecular-scale movement associated with the formation of the lamellar structure induces a macroscopic structural change. Consequently, p(DDA/TMSPA) can be considered as a new stimulus-responsive polymer.

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Section: Introductionmentioning

confidence: 99%

Self-Assembly and -Cross-Linking Lamellar Films by Nanophase Separation with Solvent-Induced Anisotropic Structural Changes

et al. 2022

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“…Moreover, the size of each structure can be tuned by changing the degree of polymerization. In general, the self-assembled structure size prepared from block copolymers is about a few tens of nanometers and highly segregated block copolymers with low-molecular-weight or block copolymers with complex structures should be synthesized to prepare a sub-10 nm structure. − On the other hand, homopolymers and statistical copolymers also form highly oriented lamellae by taking advantage of the crystallinity or liquid crystallinity of the side chains. − The lamellar periodicity of homo and statistical copolymer depends on the length of the side chain and is usually approximately a few nanometers. The periodicity is 1 order of magnitude lower than that prepared from block copolymers.…”

Section: Introductionmentioning

confidence: 99%

Self-Assembled Lamellar Films of Comb-Shaped Copolymers by Segregation between Hydrophobic Side Chains and the Main Chain with Hydrophilic Comonomers

2021

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Self-assembled lamellar films of poly(N-dodecyl acrylamide-stat-vinyl phosphonic acid) [p(DDA/VPA)] were formed via the segregation between the hydrophilic main chain and VPA and dodecyl side chains. p(DDA/VPA) copolymers were synthesized by free-radical copolymerization of DDA and VPA with VPA molar concentrations of 19% [p(DDA/VPA19)] and 64% [p(DDA/VPA64)]. Both copolymers exhibited a glasstransition temperature (T g ) and melting temperature for p-(DDA/VPA19), but no crystalline or liquid-crystalline phasetransition temperatures, which suggests that both copolymers are amorphous. Thin films of the copolymers were prepared by spin coating, and the structure of the films was studied by X-ray diffraction (XRD) measurements. The as-cast films of the copolymers showed broad diffraction patterns, which suggested the formation of alkyl nanodomains similar to that observed in the pDDA homopolymers. On the other hand, the XRD patterns for both copolymer films showed a sharp Bragg diffraction in the low-q region after annealing at 60 °C. Furthermore, the p(DDA/VPA19) film showed firstand second-order Bragg diffractions with a ratio of 1:2. These XRD patterns suggest that the copolymer films form an ordered lamellar structure. We concluded that the main chain became more hydrophilic by the introduction of VPA, resulting in an increased segregation force relative to the hydrophobic dodecyl side chains, which induces the formation of lamellae. Moreover, doping a p(DDA/VPA64) film with imidazole increased the ordering and uniformity of the lamellar structures due to the increased segregation force by the formation of ion pairs in the hydrophilic comonomer. In their entirety, the results show that statistical copolymerization can be used as a new method to create self-assembled structures.

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“…[17] Moreover, Terashima et al have reported that amphiphilic random copolymers composed of octadecyl (meth)acrylate and oligo ethylene glycol form lamellar structures via phase separation of the crystallized octadecyl side chains and hydrophilic oligo ethylene glycol side chains. [18,19] They also controlled d values from 5.3 to 6.3 nm by changing comonomer ratio of octadecyl (meth)acrylate and oligo ethylene glycol. These reports suggest that it is possible to create a few nanometer size self-assembled structures in homopolymers and random copolymers by using segregation between the main chains and side chains or comonomers.…”

Section: Introductionmentioning

confidence: 99%

Rapid Formation of a Lamellar Structure in an Amphiphilic Comb‐Shaped Polymer by Nanophase Separation Using Microwave–Humidity Annealing

Ohke

Matsui

2021

Macro Chemistry & Physics

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Microwave irradiation is applied to rapidly prepare highly ordered lamellar structures of amphiphilic comb-shaped polymers via nanophase separation. Amphiphilic comb-shaped polymer of poly(N-dodecyl acrylamide) (pDDA) is synthesized by free radical polymerization. Differential scanning calorimetry (DSC) and X-ray diffraction results indicate that pDDA is amorphous at room temperature. Exposing pDDA powder to microwave irradiation in the presence of water (microwave-humidity annealing) converts the structure into lamellae. The water molecules absorb the microwaves, and their temperature rapidly increases above the glass-transition temperature (T g ) of pDDA. Moreover, a fraction of the heated water is adsorbed at the amide moiety, which increases the nanosegregation with the alkyl side chains. As a result, pDDA forms a lamellar structure by nanophase separation between the main chain with water-containing amide moieties and the alkyl side chains. The rapid increase in temperature results in a fast formation (a few tens of seconds) of the lamellae. Moreover, the microwave-humidity annealing of pDDA thin films on Si substrates results in a uniaxial lamellar structure. These results indicate that microwave-humidity annealing is a simple method to rapidly form a self-assembled structure in homopolymers by nanophase separation.

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Design guide of amphiphilic crystalline random copolymers for sub-10 nm microphase separation

Abstract: Sub-10 nm lamellar structures are efficiently constructed by the pendant microphase separation of amphiphilic crystalline random copolymers with broad molecular weight distribution that are obtained from free radical copolymerization.

Cited by 14 publications

References 50 publications

Self-Assembly and -Cross-Linking Lamellar Films by Nanophase Separation with Solvent-Induced Anisotropic Structural Changes

Self-Assembly and -Cross-Linking Lamellar Films by Nanophase Separation with Solvent-Induced Anisotropic Structural Changes

Self-Assembled Lamellar Films of Comb-Shaped Copolymers by Segregation between Hydrophobic Side Chains and the Main Chain with Hydrophilic Comonomers

Rapid Formation of a Lamellar Structure in an Amphiphilic Comb‐Shaped Polymer by Nanophase Separation Using Microwave–Humidity Annealing

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