Crystallization ability of poly(lactic acid) block segments in templating poly(ethylene oxide-b-lactic acid) diblock copolymers affects the resulting structures of mesoporous silicas

Altukhov, Oleksii; Kuo, Shiao‐Wei

doi:10.1039/c5ra01096a

Cited by 9 publications

(9 citation statements)

References 44 publications

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“…Figure a shows the nitrogen adsorption‐desorption curves related to the TEOS:co‐templates=3:1 mass ratio, which are also typical type‐IV isotherms with H 2 ‐type (ink‐bottle) hysteresis loops, assigned to capillary condensation. The contribution in the relative pressure ranging from 0.45 to 0.95 is related to PEO‐ b ‐PLA and the one in the relative pressure range from 0.45 to 0.80 can be assigned to F127 ,. The adsorption isotherm curves of T3EA50F50 and T3EA25F75 have two distinguishable components.…”

Section: Resultsmentioning

confidence: 98%

“…[9‐17] For example, the amphiphilic ABA‐type poly(ethylene oxide‐b‐propylene oxide‐b‐ethylene oxide) triblock copolymer (PEO‐ b ‐PPO‐ b ‐PEO, Pluronic F127) has been used for the synthesis of mesoporous silica with a controlled mesostructured, from hexagonal cylinder to body‐centered cubic (BCC), by changing the concentration of tetraethyl orthosilicate (TEOS) . In addition, diblock copolymers such as poly(ethylene oxide‐ b ‐caprolactone) (PEO‐ b ‐PCL),‐ poly(ethylene oxide‐ b ‐lactide) (PEO‐ b ‐PLA), poly(ethylene oxide‐ b ‐L‐lactide) (PEO‐ b ‐PLLA), [13] poly(ethylene oxide‐ b ‐methyl methacrylate) (PEO‐ b ‐PMMA) and poly(ethylene oxide‐ b ‐styrene) (PEO‐ b ‐PS) have been widely studied as templates to prepare mesoporous silica. However, these templates usually lead to unimodal pore distributions due to the presence of a single hydrophobic segment (PCL, PLA, PLLA, PMMA and PS).…”

Section: Introductionmentioning

confidence: 99%

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Co-templating Synthesis of Bimodal Mesoporous Silica for Potential Drug Carrier

et al. 2016

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Bimodal mesoporous silica is prepared by co-templating method using PEO-b-PLA diblock copolymer and F127 triblock copolymer. The pore size distribution of the mesoporous silica is bimodal, based on small angle X-ray scattering, transmission electron microscopy, and nitrogen adsorption-desorption isotherms analyses, and can be divided into the larger pores, originating from PEO-b-PLA, and the smaller pores, originating from F127. In addition, we are able to ascertain that the F127 triblock copolymer not only produces the smaller pores, but also acts as a swelling agent in the formation of the larger pores. This novel bimodal mesoporous silica is further successfully employed as a drug-carrier for doxorubicin in ambient conditions.

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Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Co-templating Synthesis of Bimodal Mesoporous Silica for Potential Drug Carrier

et al. 2016

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“…Using a commercial pluronic-type poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) triblock copolymer as the template is the most widely used approach to preparing mesoporous materials; however, because of the limitation presented by the molecular weight of this kind of triblock copolymer, it is difficult to prepare mesoporous phenolic or carbon with pore size >10 nm [36][37][38][39][40][41]. As a result, using a high-molecular-weight long hydrophobic block in a PEO-based block copolymer including poly(ethylene-oxide-b-styrene) (PEO-b-PS) [42][43][44], poly(ethylene oxide-b-caprolactone) (PEO-b-PCL) [33][34][35][45][46][47], poly(ethylene-oxide-b-methyl methacrylate) (PEO-b-PMMA) [48], or poly(ethylene oxide-b-lactic acid) (PEO-b-PLA) [49,50] as the templates is the easiest way to prepare large mesoporous materials. For example, employing PEO 125 -b-PS 230 and PEO 114 -b-PLA 94 diblock copolymers as a template could provide the large pore size (23 and 21 nm, respectively) required to prepare mesoporous carbon [42,50].…”

Section: Introductionmentioning

confidence: 99%

“…Compared with the PEO114-b-PLA94 diblock copolymer [50], this LEL triblock copolymer possessed high molecular weight as a template and thus could provide large mesoporous carbons as expected. In addition, as also compared with PCL-b-PEO-b-PCL triblock copolymer, using the PLA-b-PEO-b-PLA triblock copolymer as the template had two advantages, including: (1) No crystallization of the PLA segment of the template occurred since the self-assembled structure strongly affected the microphase separation from the crystallization of the PCL segment [49]; (2) The very weak hydrogen bonding interaction of the PLA segment could provide larger pore size of mesoporous carbons with a hydrophobic segment having a similar molecular weight [50]. Therefore, a mesoporous carbon with large pore size could be obtained using this LEL triblock copolymer as a template in this study.…”

Section: Introductionmentioning

confidence: 99%

High-Molecular-Weight PLA-b-PEO-b-PLA Triblock Copolymer Templated Large Mesoporous Carbons for Supercapacitors and CO2 Capture

et al. 2020

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High-molecular-weight PLA440-b-PEO454-b-PLA440 (LEL) triblock copolymer was synthesized through simple ring-opening polymerization (ROP) by using the commercial homopolymer HO-PEO454-OH as the macro-initiator. The material acted as a single template to prepare the large mesoporous carbons by using resol-type phenolic resin as a carbon source. Self-assembled structures of phenolic/LEL blends mediated by hydrogen bonding interaction were determined by FTIR and SAXS analyses. Through thermal curing and carbonization procedures, large mesoporous carbons (>50 nm) with a cylindrical structure and high surface area (>600 m2/g) were obtained because the OH units of phenolics prefer to interact with PEO block rather than PLA block, as determined by FTIR spectroscopy. Furthermore, higher CO2 capture and good energy storage performance were observed for this large mesoporous carbon, confirming that the proposed approach provides an easy method for the preparation of large mesoporous materials.

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“…[ 34 ] Fortunately, crystalline PLLA segments can readily be changed into amorphous PLA segments when incorporating an equal number of D ‐ and L ‐forms in which the overall PLA segment is not chiral. [ 35 ] In this study, we synthesized a PEO 114 ‐ b ‐PLA 94 diblock copolymer through simple ROP when using commercial PEO‐OH as a macroinitiator. We then prepared mesoporous carbons by using resol as the carbon source and the PEO‐ b ‐PLA as a template, through a process of thermal curing, calcination, carbonization, and activation ( Scheme ).…”

Section: Introductionmentioning

confidence: 99%

Varying the Hydrogen Bonding Strength in Phenolic/PEO‐b‐PLA Blends Provides Mesoporous Carbons Having Large Accessible Pores Suitable for Energy Storage

Lee

Ahmed

et al. 2020

Macro Chemistry & Physics

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as efficient electron transfer media to improve the performance of electric double-layer capacitors (EDLCs). [9] Furthermore, the blending of a self-assembled block copolymer with the carbon source (e.g., phenolic resin) is becoming more widespread. This method has the advantage of providing well-ordered mesoporous structures that can be used efficiently in various applications. [10,11] Typically, a block copolymer that forms a self-assembled structure is mixed with a carbon source to obtain various dimensional carbon structures. The blending of a commercial Pluronic-type triblock copolymer, such as poly(ethylene oxide-b-propylene oxideb-ethylene oxide), as the template is the method used most widely to prepare mesoporous materials. [12][13][14][15][16][17][18][19] Because of limitations in molecular weight and composition, it can, however, be difficult to prepare mesoporous materials having pore sizes of greater than 10 nm when using Pluronic-type triblock copolymers. Block copolymers featuring long hydrophobic segments and high molecular weight-for instance, poly(ethylene oxideb-styrene) (PEO-b-PS) [20,21] and poly(ethylene oxide-b-methyl methacrylate) (PEO-b-PMMA) [22] -are promising candidates as templates to prepare large-pore-size mesoporous carbons. For example, Zhao et al. prepared mesoporous carbons with long-range order, large surface areas (>1500 m 2 g −1 ), and large pores (≈23 nm) when using PEO 125 -b-PS 230 as the template as displayed in Scheme S1a-c in the Supporting Information. [21] With PEO 125 -b-PMMA 114 as the template, they obtained mesoporous carbons having large surface areas (>1500 m 2 g −1 ) and pores (≈10 nm) [22] when applying resol as the carbon source. Mesoporous carbons with smaller pores but thicker walls were obtained when using PEO-b-PMMA as the template, rather than PEO-b-PS, because the phenolic OH units could interact strongly with the PEO segment (interassociation equilibrium constant (K A ) = 286) [23] and weakly with the PMMA CO units (K A = 20) [24,25] through hydrogen bonding, but not with the hydrophobic PS segment. Indeed, the PS block segment would undergo complete microphase In this study, mesoporous carbons are prepared by using a resol-type phenolic resin as the carbon source and poly(ethylene oxide-b-lactic acid) (PEO-b-PLA) copolymer as the template, with a process of thermal curing, calcination, carbonization, and activation. The structures of these mesoporous carbons are strongly influenced by the self-assembled structures formed from phenolic/PEO-b-PLA blends, varying from double-gyroid, to cylinder, and finally to spherical micelle structures upon increasing the phenolic concentrations. The large pores (>20 nm) and high surface areas (>1000 m 2 g −1 ) of these activated mesoporous carbons arise because the phenolic resin interacts only with the PEO segment (i.e., not with the PLA segment) through hydrogen bonding; thus, the relative wall thickness of the phenolic matrix decreases after template removal (thereby increasing the pore size), similar to the beha...

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Crystallization ability of poly(lactic acid) block segments in templating poly(ethylene oxide-b-lactic acid) diblock copolymers affects the resulting structures of mesoporous silicas

Abstract: Eliminating the crystallization ability of PLLA to amorphous PLA block segment allowed us to obtain long-range-ordered mesoporous materials.

Cited by 9 publications

References 44 publications

Co-templating Synthesis of Bimodal Mesoporous Silica for Potential Drug Carrier

Co-templating Synthesis of Bimodal Mesoporous Silica for Potential Drug Carrier

High-Molecular-Weight PLA-b-PEO-b-PLA Triblock Copolymer Templated Large Mesoporous Carbons for Supercapacitors and CO2 Capture

Varying the Hydrogen Bonding Strength in Phenolic/PEO‐b‐PLA Blends Provides Mesoporous Carbons Having Large Accessible Pores Suitable for Energy Storage

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