The double helix of a polysaccharide, xanthan was unwound by heating (denaturation) and rewound by cooling (renaturation) in acidic (0.01 M HCl) and basic (0.01 M NaOH) solutions. Circular dichroism spectra of xanthan renatured in the acidic and basic solutions were similar to those of native xanthan, which suggests that the local helical structures of the renatured xanthan were recovered by renaturation. The changes in the molar mass and intrinsic viscosity of xanthan induced by renaturation in the acidic solution can be explained by the renaturation scheme in the neutral solution, as reported previously. (Matsuda et al. Polym. J. 41, 526-532, 2009). Both the molar mass and radius of gyration of xanthan in the basic solution were decreased by denaturation and renaturation, and the molar mass dependence of the radius of gyration was similar to that of native xanthan. This change can be explained by the formation of a hairpin structure during renaturation in the basic solutions. Structural changes induced by thermal denaturation and renaturation of a double-helical polysaccharide xanthan in acidic and basic solutions were investigated mainly by light scattering measurements and circular dichroism spectroscopy. In acidic solution, the renatured components were almost the same as those in native components, while small amounts of aggregates and a hairpin structure were produced via denaturation and renaturation processes. In basic solution, the double helices were dissociated upon heating into the single coils, and high molar mass sample produced a hairpin structure after subsequent renaturation.
在酸性（0.01 M HCl）和碱性（0.01 M NaOH）溶液中，加热（变性）黄原胶的双螺旋结构，冷却（再变性）黄原胶的双螺旋结构。在酸性和碱性溶液中变性的黄原胶的圆二色光谱与原生黄原胶相似，这表明变性黄原胶的局部螺旋结构通过变性得到了恢复。黄原胶在酸性溶液中的变性引起的摩尔质量和固有粘度的变化可以用中性溶液中的变性方案来解释，这在以前的报道中已有报道。(Matsuda et al. Polym. J. 41, 526-532, 2009）。通过变性和再变性，黄原胶在碱性溶液中的摩尔质量和回转半径都减小了，回 转半径的摩尔质量依赖性与原生黄原胶相似。这种变化可以解释为在碱性溶液中重新变性时形成了发夹结构。
{"title":"Thermal denaturation and renaturation of a double-helical polysaccharide xanthan in acidic and basic solutions","authors":"Yasuhiro Matsuda, Ryoga Saiki, Kaede Sato, Atsuya Kashiwagi, Kazuto Yoshiba","doi":"10.1038/s41428-024-00892-y","DOIUrl":"10.1038/s41428-024-00892-y","url":null,"abstract":"The double helix of a polysaccharide, xanthan was unwound by heating (denaturation) and rewound by cooling (renaturation) in acidic (0.01 M HCl) and basic (0.01 M NaOH) solutions. Circular dichroism spectra of xanthan renatured in the acidic and basic solutions were similar to those of native xanthan, which suggests that the local helical structures of the renatured xanthan were recovered by renaturation. The changes in the molar mass and intrinsic viscosity of xanthan induced by renaturation in the acidic solution can be explained by the renaturation scheme in the neutral solution, as reported previously. (Matsuda et al. Polym. J. 41, 526-532, 2009). Both the molar mass and radius of gyration of xanthan in the basic solution were decreased by denaturation and renaturation, and the molar mass dependence of the radius of gyration was similar to that of native xanthan. This change can be explained by the formation of a hairpin structure during renaturation in the basic solutions. Structural changes induced by thermal denaturation and renaturation of a double-helical polysaccharide xanthan in acidic and basic solutions were investigated mainly by light scattering measurements and circular dichroism spectroscopy. In acidic solution, the renatured components were almost the same as those in native components, while small amounts of aggregates and a hairpin structure were produced via denaturation and renaturation processes. In basic solution, the double helices were dissociated upon heating into the single coils, and high molar mass sample produced a hairpin structure after subsequent renaturation.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"56 6","pages":"629-637"},"PeriodicalIF":2.8,"publicationDate":"2024-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139911072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-15DOI: 10.1038/s41428-024-00888-8
Hiroyuki Taniyama, Koji Takagi
Here, cellulose nanocrystal (CNC) films were chemically modified in a two-stage process to realize surface wettability control through the introduction of CO2 gas. In addition to controlling the surface structure of the silylation-modified CNC film, functional groups derived from silane compounds were installed, and the corresponding effects on the resulting chemical modification were investigated. In the first stage, methyltriethoxysilane (MTES) and hexyltriethoxysilane (HTES) combined with tetraethoxysilane (TEOS) were subjected to condensation under alkaline conditions. In the second stage, (3-(N,N-dimethylamino)propyl)trimethoxysilane (DMAPS) generated an amino group to control the surface wettability by adsorption CO2 gas. Then, the silylation-modified CNC film was fabricated on a glass substrate by spin coating. Fourier transform infrared (FT-IR), nuclear magnetic resonance (29Si-NMR), and X-ray photoelectron spectroscopy (XPS) inspection indicated that the silane compounds were bonded to the CNC film surface and that tertiary amino groups were successfully introduced. The surface structure of the silylation-modified CNC film was analyzed by atomic force microscopy (AFM), and the surface roughness calculating indicated a root-mean-square roughness (RMS) of 4.2 nm. The water contact angles before and after the CO2 gas treatment were evaluated as 73o and 22o, respectively. The modification of cellulose nanocrystal film using alkyl silane and silane containing tertiary amino groups was performed in a suspension state. Control of the surface structure and functionalization by silane compounds was conducted in the two-stage process. Wettability change property of the silylation-modified CNC triggered by CO2 was demonstrated.
{"title":"CO2 gas-triggered wettability control of silylation-modified CNC films by manipulating the surface structure and introducing tertiary amino groups","authors":"Hiroyuki Taniyama, Koji Takagi","doi":"10.1038/s41428-024-00888-8","DOIUrl":"10.1038/s41428-024-00888-8","url":null,"abstract":"Here, cellulose nanocrystal (CNC) films were chemically modified in a two-stage process to realize surface wettability control through the introduction of CO2 gas. In addition to controlling the surface structure of the silylation-modified CNC film, functional groups derived from silane compounds were installed, and the corresponding effects on the resulting chemical modification were investigated. In the first stage, methyltriethoxysilane (MTES) and hexyltriethoxysilane (HTES) combined with tetraethoxysilane (TEOS) were subjected to condensation under alkaline conditions. In the second stage, (3-(N,N-dimethylamino)propyl)trimethoxysilane (DMAPS) generated an amino group to control the surface wettability by adsorption CO2 gas. Then, the silylation-modified CNC film was fabricated on a glass substrate by spin coating. Fourier transform infrared (FT-IR), nuclear magnetic resonance (29Si-NMR), and X-ray photoelectron spectroscopy (XPS) inspection indicated that the silane compounds were bonded to the CNC film surface and that tertiary amino groups were successfully introduced. The surface structure of the silylation-modified CNC film was analyzed by atomic force microscopy (AFM), and the surface roughness calculating indicated a root-mean-square roughness (RMS) of 4.2 nm. The water contact angles before and after the CO2 gas treatment were evaluated as 73o and 22o, respectively. The modification of cellulose nanocrystal film using alkyl silane and silane containing tertiary amino groups was performed in a suspension state. Control of the surface structure and functionalization by silane compounds was conducted in the two-stage process. Wettability change property of the silylation-modified CNC triggered by CO2 was demonstrated.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"56 6","pages":"609-617"},"PeriodicalIF":2.8,"publicationDate":"2024-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41428-024-00888-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139769496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Irreversible adsorption of polymer chains from a melt on a substrate surface can be strongly affected by interfacial interactions. In this study, we examined the adsorption of two polymers, poly(tert-butyl methacrylate) (PtBMA) and poly(ethyl methacrylate) (PEMA), on a silica surface at temperatures above their glass transition temperatures. The degree of adsorption γ(t) over time was evaluated with variations of storage heat capacity determined with alternating current chip nanocalorimetry (in-situ measurement of a buried interface). γ(t) revealed two-step profiles for both polymers. At the second stage of adsorption (regime II), the slope of a plot of γ(t) vs. log t increased as adsorption proceeded; this trend has not been reported for other polymers and may be characteristic of the present polymers. The trend observed in regime II suggested that the unadsorbed free chains near the interface became less mobile and were incorporated into the adsorbed layer via interactions with the tails of the chains directly attached to the substrate surface. The increasing slope in regime II was more prominent for PtBMA than for PEMA. In addition, a difference was observed for PtBMA and PEMA in the atomic force microscopy images of the exposed adsorption layer surfaces. We examined the adsorption behavior of poly(tert-butyl methacrylate) (PtBMA) and poly(ethyl methacrylate) (PEMA), on a silica surface. Time-evolution of the degree of adsorption γ(t) was evaluated with chip nanocalorimetry. γ(t) revealed a two-step profile for both polymers. At the second stage of adsorption, the slope of γ(t) vs. log t increased as adsorption proceeded; this trend has not been reported for other polymers so far. In addition, atomic force microscopy images of the adsorbed layers revealed corresponding evolutions of the morphologies.
熔体中的聚合物链在基底表面的不可逆吸附会受到界面相互作用的强烈影响。在本研究中，我们研究了聚甲基丙烯酸叔丁酯（PtBMA）和聚甲基丙烯酸乙酯（PEMA）这两种聚合物在高于其玻璃化转变温度时在二氧化硅表面的吸附情况。吸附程度γ(t)随时间的变化通过交变电流芯片纳米焦度计（埋藏界面的原位测量）测定的存储热容量变化进行评估。两种聚合物的γ(t)都显示出两个阶段的曲线。在吸附的第二阶段（阶段 II），随着吸附的进行，γ(t) 对 log t 曲线的斜率增加；这种趋势在其他聚合物中没有报道过，可能是本聚合物的特征。在状态 II 中观察到的趋势表明，界面附近未吸附的游离链的流动性变小，并通过与直接附着在基底表面的链尾的相互作用而被吸附到吸附层中。与 PEMA 相比，PtBMA 在第二阶段的斜率增加更为明显。此外，在暴露的吸附层表面的原子力显微镜图像中也观察到了 PtBMA 和 PEMA 的差异。
{"title":"Melt adsorption of poly(tert-butyl methacrylate) and poly(ethyl methacrylate) on silica studied with chip nanocalorimetry","authors":"Minato Ishihara, Tomoya Watanabe, Toyoaki Hirata, Takashi Sasaki","doi":"10.1038/s41428-024-00895-9","DOIUrl":"10.1038/s41428-024-00895-9","url":null,"abstract":"Irreversible adsorption of polymer chains from a melt on a substrate surface can be strongly affected by interfacial interactions. In this study, we examined the adsorption of two polymers, poly(tert-butyl methacrylate) (PtBMA) and poly(ethyl methacrylate) (PEMA), on a silica surface at temperatures above their glass transition temperatures. The degree of adsorption γ(t) over time was evaluated with variations of storage heat capacity determined with alternating current chip nanocalorimetry (in-situ measurement of a buried interface). γ(t) revealed two-step profiles for both polymers. At the second stage of adsorption (regime II), the slope of a plot of γ(t) vs. log t increased as adsorption proceeded; this trend has not been reported for other polymers and may be characteristic of the present polymers. The trend observed in regime II suggested that the unadsorbed free chains near the interface became less mobile and were incorporated into the adsorbed layer via interactions with the tails of the chains directly attached to the substrate surface. The increasing slope in regime II was more prominent for PtBMA than for PEMA. In addition, a difference was observed for PtBMA and PEMA in the atomic force microscopy images of the exposed adsorption layer surfaces. We examined the adsorption behavior of poly(tert-butyl methacrylate) (PtBMA) and poly(ethyl methacrylate) (PEMA), on a silica surface. Time-evolution of the degree of adsorption γ(t) was evaluated with chip nanocalorimetry. γ(t) revealed a two-step profile for both polymers. At the second stage of adsorption, the slope of γ(t) vs. log t increased as adsorption proceeded; this trend has not been reported for other polymers so far. In addition, atomic force microscopy images of the adsorbed layers revealed corresponding evolutions of the morphologies.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"56 6","pages":"619-628"},"PeriodicalIF":2.8,"publicationDate":"2024-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41428-024-00895-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139769377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The low crystallinity of cellulose II makes industrial use a major challenge. In our previous report, we proposed a mechanism for improvement of the crystallinity of cellulose II during posttreatment with a dilute NaOH solution. Specifically, rearrangements of the cellulose molecules occurred only near inaccessible surfaces through which NaOH penetrated, resulting in conversion into crystalline regions. To verify our proposed mechanism and to improve the crystallinity further, we performed both long-term single-cycle and multicycle posttreatments with dilute NaOH solutions. Multiple posttreatment cycles under optimal conditions increased the crystallinity by up to approximately 20%. In contrast, long-term single-cycle posttreatment led to crystallinity improvements of only up to approximately 10%. Changes in the proportions of the regions during multiple cycles after treatment supported our proposed mechanism. During multiple posttreatment cycles, the products were converted to crystalline regions only on the inaccessible surfaces enlarged by the previous posttreatment cycle, which increased the crystal sizes in each cycle. Optimization of the treatment times used during the multiple posttreatment cycles led to crystallinity improvements with fewer posttreatment cycles. Our investigations of the mechanism for crystallinity improvement will contribute to structural elucidation of cellulose II and the efficient preparation of highly crystalline cellulose II. The study on the improvement of the crystallinity of cellulose II by post-treatment with dilute NaOH solution showed that the crystallinity was significantly improved by post-treatment with multiple cycles. The NaOH in an aqueous NaOH solution penetrated only inaccessible surface regions, and cellulose rearrangement occurred only in these regions during post-treatment, improving crystal size. In the second and subsequent posttreatment cycles, cellulose rearrangement occurred only at the inaccessible surfaces expanded during the previous post-treatment cycle, crystallization progressed toward amorphous regions away from the initial crystalline regions.
由于纤维素 II 的结晶度较低，因此在工业应用中面临着巨大挑战。在之前的报告中，我们提出了用稀 NaOH 溶液进行后处理时提高纤维素 II 结晶度的机制。具体来说，纤维素分子的重排只发生在 NaOH 无法渗透的表面附近，从而转化为结晶区域。为了验证我们提出的机制并进一步提高结晶度，我们用稀 NaOH 溶液进行了长期单循环和多循环后处理。在最佳条件下进行的多次后处理可将结晶度提高约 20%。相比之下，长期单循环后处理最多只能提高约 10%的结晶度。处理后多次循环期间各区域比例的变化支持了我们提出的机制。在多个后处理周期中，产物仅在前一个后处理周期扩大的无法进入的表面上转化为结晶区域，从而增加了每个周期的晶体尺寸。通过优化多个后处理周期中的处理时间，可以在减少后处理周期的情况下提高结晶度。我们对结晶度改善机制的研究将有助于纤维素 II 的结构阐明和高结晶纤维素 II 的高效制备。
{"title":"Crystallinity improvements in cellulose II after multiple posttreatment cycles with a dilute NaOH solution","authors":"Yuki Kugo, Satoshi Nomura, Takuya Isono, Masashi Fujiwara, Toshifumi Satoh, Hirofumi Tani, Tomoki Erata, Kenji Tajima","doi":"10.1038/s41428-024-00890-0","DOIUrl":"10.1038/s41428-024-00890-0","url":null,"abstract":"The low crystallinity of cellulose II makes industrial use a major challenge. In our previous report, we proposed a mechanism for improvement of the crystallinity of cellulose II during posttreatment with a dilute NaOH solution. Specifically, rearrangements of the cellulose molecules occurred only near inaccessible surfaces through which NaOH penetrated, resulting in conversion into crystalline regions. To verify our proposed mechanism and to improve the crystallinity further, we performed both long-term single-cycle and multicycle posttreatments with dilute NaOH solutions. Multiple posttreatment cycles under optimal conditions increased the crystallinity by up to approximately 20%. In contrast, long-term single-cycle posttreatment led to crystallinity improvements of only up to approximately 10%. Changes in the proportions of the regions during multiple cycles after treatment supported our proposed mechanism. During multiple posttreatment cycles, the products were converted to crystalline regions only on the inaccessible surfaces enlarged by the previous posttreatment cycle, which increased the crystal sizes in each cycle. Optimization of the treatment times used during the multiple posttreatment cycles led to crystallinity improvements with fewer posttreatment cycles. Our investigations of the mechanism for crystallinity improvement will contribute to structural elucidation of cellulose II and the efficient preparation of highly crystalline cellulose II. The study on the improvement of the crystallinity of cellulose II by post-treatment with dilute NaOH solution showed that the crystallinity was significantly improved by post-treatment with multiple cycles. The NaOH in an aqueous NaOH solution penetrated only inaccessible surface regions, and cellulose rearrangement occurred only in these regions during post-treatment, improving crystal size. In the second and subsequent posttreatment cycles, cellulose rearrangement occurred only at the inaccessible surfaces expanded during the previous post-treatment cycle, crystallization progressed toward amorphous regions away from the initial crystalline regions.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"56 5","pages":"517-527"},"PeriodicalIF":2.8,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139769511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-07DOI: 10.1038/s41428-024-00889-7
Hiroki Kurohara, Yumiko Hori, Munenori Numata, Gaku Fukuhara
The ability to sense saccharides in aqueous media using conventional supramolecular approaches was a turning point in modern chemistry. Herein, we performed oligosaccharide sensing using fluorophore-modified branched glucans. Through the newly developed glucan-based chemosensor, acarbose sensing was achieved in a selectively and sensitive manner. The optical properties and morphological changes in the chemosensor were investigated, revealing that the globule-to-coaggregation process plays a key role in oligosaccharide sensing. The fluorophore-modified glucan, TPE-6BG3 adopts an extended, random-coiled form in DMSO, which does not fluoresce. The morphology of the TPE-6BG3 chemosensor changes drastically to a dynamic globule in aqueous media. The dynamic, “induced-fit” globule selectively and sensitively recognizes the medicinally-useful tetrasaccharide, acarbose via glucan-saccharide coaggregation.
{"title":"Fluorophore-glucan conjugate for oligosaccharide sensing in aqueous media","authors":"Hiroki Kurohara, Yumiko Hori, Munenori Numata, Gaku Fukuhara","doi":"10.1038/s41428-024-00889-7","DOIUrl":"10.1038/s41428-024-00889-7","url":null,"abstract":"The ability to sense saccharides in aqueous media using conventional supramolecular approaches was a turning point in modern chemistry. Herein, we performed oligosaccharide sensing using fluorophore-modified branched glucans. Through the newly developed glucan-based chemosensor, acarbose sensing was achieved in a selectively and sensitive manner. The optical properties and morphological changes in the chemosensor were investigated, revealing that the globule-to-coaggregation process plays a key role in oligosaccharide sensing. The fluorophore-modified glucan, TPE-6BG3 adopts an extended, random-coiled form in DMSO, which does not fluoresce. The morphology of the TPE-6BG3 chemosensor changes drastically to a dynamic globule in aqueous media. The dynamic, “induced-fit” globule selectively and sensitively recognizes the medicinally-useful tetrasaccharide, acarbose via glucan-saccharide coaggregation.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"56 5","pages":"473-480"},"PeriodicalIF":2.8,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41428-024-00889-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139769536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-02DOI: 10.1038/s41428-023-00850-0
Yu Hoshino, Shoma Aki
Capturing CO2 from various sources, such as postcombustion exhaust gases and the atmosphere, is essential for a sustainable human society. Effective CO2 separation materials such as adsorbents and membranes are of utmost importance in efficient CO2 capture. This short review is focused on CO2 separation materials consisting of hydrogel particles. The first chapter introduces stimuli-responsive micro- and nanogel particles that reversibly absorb CO2 in response to thermal stimuli. The development of temperature-responsive hydrogel films comprising gel particles for reversible CO2 capture is introduced. The importance of choosing amines with optimal pKa values for efficient CO2 capture from various sources is explained in detail. The assembly of CO2 separation membranes consisting of amine-containing hydrogel particles is introduced in the final chapter. The paper highlights the promise of separation materials consisting of hydrogel particles for efficient CO2 capture from postcombustion gases and air and the prospects for further advances in this area. In this short review, we focus on the development of CO2 separation materials consisting of hydrogel particles. The review starts with development of stimuli responsive micro- and nano-gel particles that reversibly absorb CO2 isn response. The next chapter focuses on the development of temperature-responsive hydrogel films consisting of gel particles that reversibly absorb CO2 and the importance of optimizing the pKa values of the amines in the particles. In the end, assembly of defect-free nano-meter-thick CO2 separation membranes consisting of the amine containing hydrogel particles are introduced.
{"title":"Hydrogel particles for CO2 capture","authors":"Yu Hoshino, Shoma Aki","doi":"10.1038/s41428-023-00850-0","DOIUrl":"10.1038/s41428-023-00850-0","url":null,"abstract":"Capturing CO2 from various sources, such as postcombustion exhaust gases and the atmosphere, is essential for a sustainable human society. Effective CO2 separation materials such as adsorbents and membranes are of utmost importance in efficient CO2 capture. This short review is focused on CO2 separation materials consisting of hydrogel particles. The first chapter introduces stimuli-responsive micro- and nanogel particles that reversibly absorb CO2 in response to thermal stimuli. The development of temperature-responsive hydrogel films comprising gel particles for reversible CO2 capture is introduced. The importance of choosing amines with optimal pKa values for efficient CO2 capture from various sources is explained in detail. The assembly of CO2 separation membranes consisting of amine-containing hydrogel particles is introduced in the final chapter. The paper highlights the promise of separation materials consisting of hydrogel particles for efficient CO2 capture from postcombustion gases and air and the prospects for further advances in this area. In this short review, we focus on the development of CO2 separation materials consisting of hydrogel particles. The review starts with development of stimuli responsive micro- and nano-gel particles that reversibly absorb CO2 isn response. The next chapter focuses on the development of temperature-responsive hydrogel films consisting of gel particles that reversibly absorb CO2 and the importance of optimizing the pKa values of the amines in the particles. In the end, assembly of defect-free nano-meter-thick CO2 separation membranes consisting of the amine containing hydrogel particles are introduced.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"56 5","pages":"463-471"},"PeriodicalIF":2.8,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41428-023-00850-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139664769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We prepared flexible free-standing films of trifluoropropyl-substituted open-cage silsesquioxane-pendant polysiloxane by optimizing the sol-gel reaction conditions of tris(dimethoxysilyl-ethyl-dimethylsiloxy)-heptatrifluoropropyl-substituted open-cage silsesquioxane (1). The polycondensation of 1 was fully achieved even at 50 °C for 6 h under vacuo. 29Si CP-MAS NMR analysis indicated that the flexible free-standing films, polycondensed at 50 °C and 180 °C, included cyclotrisiloxane (D3) and linear siloxane (Dlinear) structures. The elastic modulus and decomposition temperature at 5% mass weight loss (Td5) of the product by polycondensation at 180 °C under N2 were significantly greater than those for the 50 °C product. Significant changes in the UV‒vis spectra of the resulting transparent films were not observed even after 13 days of UV irradiation in air. In contrast, UV irradiation of the isobutyl-substituted counterpart under air clearly caused a decrease in its transmittance due to autoxidative degradation. Free-standing films of trifluoropropyl-substituted open-cage silsesquioxane-pendant polysiloxane by optimizing sol-gel reaction condition of tris(dimethoxysilyl-ethyl-dimethylsiloxy)-heptatrifluoropropyl-substituted open-cage silsesquioxane. Elastic modulus and the decomposition temperature for 5% weight loss under N2 of the product by polycondensation at 180 °C were significantly higher than that by polycondensation at 50 °C. Significant changes in the UV-vis spectra of the resulting transparent films were hardly observed even after 13 days of UV irradiation.
我们通过优化三(二甲氧基硅基-乙基-二甲基硅氧基)-七三氟丙基取代开式笼状硅倍半氧烷（1）的溶胶-凝胶反应条件，制备出了三氟丙基取代开式笼状硅倍半氧烷的柔性独立薄膜。1 在 50 °C 的真空条件下缩聚 6 小时即可完全缩聚。29Si CP-MAS NMR 分析表明，在 50 °C 和 180 °C 下缩聚的柔性独立薄膜包括环三硅氧烷（D3）和线性硅氧烷（Dlinear）结构。在氮气环境下于 180 ℃ 缩聚生成的产品的弹性模量和质量损失 5% 时的分解温度（Td5）明显高于 50 ℃ 的产品。即使在空气中经过 13 天的紫外线照射，也没有观察到透明薄膜的紫外可见光谱发生明显变化。相反，由于自氧化降解，在空气中紫外线照射异丁基取代物明显导致其透射率下降。
{"title":"Preparation of molecularly well-defined silicone resins based on trifluoropropyl-substituted trisilanol and their thermal, mechanical, and UV-resistance properties","authors":"Miku Kosaka, Taishi Nakano, Kenji Kanaori, Hiroaki Imoto, Kensuke Naka","doi":"10.1038/s41428-024-00886-w","DOIUrl":"10.1038/s41428-024-00886-w","url":null,"abstract":"We prepared flexible free-standing films of trifluoropropyl-substituted open-cage silsesquioxane-pendant polysiloxane by optimizing the sol-gel reaction conditions of tris(dimethoxysilyl-ethyl-dimethylsiloxy)-heptatrifluoropropyl-substituted open-cage silsesquioxane (1). The polycondensation of 1 was fully achieved even at 50 °C for 6 h under vacuo. 29Si CP-MAS NMR analysis indicated that the flexible free-standing films, polycondensed at 50 °C and 180 °C, included cyclotrisiloxane (D3) and linear siloxane (Dlinear) structures. The elastic modulus and decomposition temperature at 5% mass weight loss (Td5) of the product by polycondensation at 180 °C under N2 were significantly greater than those for the 50 °C product. Significant changes in the UV‒vis spectra of the resulting transparent films were not observed even after 13 days of UV irradiation in air. In contrast, UV irradiation of the isobutyl-substituted counterpart under air clearly caused a decrease in its transmittance due to autoxidative degradation. Free-standing films of trifluoropropyl-substituted open-cage silsesquioxane-pendant polysiloxane by optimizing sol-gel reaction condition of tris(dimethoxysilyl-ethyl-dimethylsiloxy)-heptatrifluoropropyl-substituted open-cage silsesquioxane. Elastic modulus and the decomposition temperature for 5% weight loss under N2 of the product by polycondensation at 180 °C were significantly higher than that by polycondensation at 50 °C. Significant changes in the UV-vis spectra of the resulting transparent films were hardly observed even after 13 days of UV irradiation.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"56 5","pages":"481-489"},"PeriodicalIF":2.8,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139664920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-26DOI: 10.1038/s41428-024-00885-x
Shohichi Furukawa, Hiroki Takeshita, Ken-ichi Fujita, Shohei Ida
Polymer gel catalysts are attractive due not only to their recyclability but also to the unique reaction environment in the internal space of the network structure. Appropriate design of the nanostructure around catalytically active sites in the gel network is particularly important. In this work, we aimed to control the activity and selectivity of the iridium-catalyzed N-alkylation of amine substrates with alcohols by incorporating an iridium complex into the crosslinked domain (CD) nanostructure of amphiphilic gels. A variety of gels with homogeneously dispersed CD structures containing iridium complexes with various crosslinking densities were prepared by the reversible addition–fragmentation chain transfer (RAFT) polymerization of N-isopropylacrylamide and an iridium complex monomer using a poly(N,N-dimethylacrylamide) macro-chain transfer agent (CTA) in the presence of a divinyl crosslinker. The resulting CD gel showed catalytic activity for the N-alkylation of aniline with benzyl alcohol, and importantly, the steric effect of the CD structure allowed the selective formation of a secondary amine product by controlling the access of the substrate to the iridium complex. Thus, we demonstrated selectivity control through the design of the nanospace surrounding the catalytic center using a nanostructured amphiphilic gel. To develop a novel gel catalyst system for a selective reaction, we prepared a variety of gels with homogeneously dispersed crosslinked domain (CD) structures containing iridium complexes with various crosslinking densities. The designed CD gel catalyst catalyzed the N-alkylation of aniline with benzyl alcohol, and the steric effect of the CD structure allowed the selective formation of the secondary amine product by controlling the access of the substrate to the iridium complex.
聚合物凝胶催化剂的吸引力不仅在于其可循环性，还在于网络结构内部空间的独特反应环境。适当设计凝胶网络中催化活性位点周围的纳米结构尤为重要。在这项工作中，我们旨在通过在两亲凝胶的交联域（CD）纳米结构中加入铱复合物，控制铱催化胺底物与醇的 N- 烷基化反应的活性和选择性。在二乙烯基交联剂存在下，通过使用聚（N,N-二甲基丙烯酰胺）大链转移剂（CTA）对 N-异丙基丙烯酰胺和铱络合物单体进行可逆加成-碎片链转移（RAFT）聚合，制备了多种具有均匀分散的 CD 结构的凝胶，其中含有不同交联密度的铱络合物。生成的 CD 凝胶对苯胺与苄醇的 N- 烷基化反应具有催化活性，重要的是，CD 结构的立体效应可以通过控制底物与铱络合物的接触，选择性地形成仲胺产物。因此，我们利用纳米结构的两亲凝胶设计了催化中心周围的纳米空间，从而证明了选择性控制。
{"title":"Selective N-alkylation catalyzed by polymer gels with crosslinked domains containing iridium complexes","authors":"Shohichi Furukawa, Hiroki Takeshita, Ken-ichi Fujita, Shohei Ida","doi":"10.1038/s41428-024-00885-x","DOIUrl":"10.1038/s41428-024-00885-x","url":null,"abstract":"Polymer gel catalysts are attractive due not only to their recyclability but also to the unique reaction environment in the internal space of the network structure. Appropriate design of the nanostructure around catalytically active sites in the gel network is particularly important. In this work, we aimed to control the activity and selectivity of the iridium-catalyzed N-alkylation of amine substrates with alcohols by incorporating an iridium complex into the crosslinked domain (CD) nanostructure of amphiphilic gels. A variety of gels with homogeneously dispersed CD structures containing iridium complexes with various crosslinking densities were prepared by the reversible addition–fragmentation chain transfer (RAFT) polymerization of N-isopropylacrylamide and an iridium complex monomer using a poly(N,N-dimethylacrylamide) macro-chain transfer agent (CTA) in the presence of a divinyl crosslinker. The resulting CD gel showed catalytic activity for the N-alkylation of aniline with benzyl alcohol, and importantly, the steric effect of the CD structure allowed the selective formation of a secondary amine product by controlling the access of the substrate to the iridium complex. Thus, we demonstrated selectivity control through the design of the nanospace surrounding the catalytic center using a nanostructured amphiphilic gel. To develop a novel gel catalyst system for a selective reaction, we prepared a variety of gels with homogeneously dispersed crosslinked domain (CD) structures containing iridium complexes with various crosslinking densities. The designed CD gel catalyst catalyzed the N-alkylation of aniline with benzyl alcohol, and the steric effect of the CD structure allowed the selective formation of the secondary amine product by controlling the access of the substrate to the iridium complex.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"56 5","pages":"561-565"},"PeriodicalIF":2.8,"publicationDate":"2024-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41428-024-00885-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139584140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-25DOI: 10.1038/s41428-023-00876-4
Yingjun An, Tomoko Kajiwara, Adchara Padermshoke, Thinh Van Nguyen, Sinan Feng, Hiroyasu Masunaga, Yutaka Kobayashi, Hiroshi Ito, Sono Sasaki, Atsuhiko Isobe, Atsushi Takahara
The photooxidative degradation and fragmentation behaviors of isotactic polypropylene (itPP) were simulated in laboratory after various postconditions, such as quenching, gradual cooling and drawing, using an artificial weathering machine and a blender. The crystallinity of the itPP films and orientation of the molecular chains play important roles in the photooxidation of the itPP films. Compared to quenched itPP films with the same ultraviolet (UV) exposure time, highly oriented itPP films and gradually cooled itPP films with higher crystallinity exhibited a lower rate of photooxidative degradation. To clarify the photooxidative degradation mechanism, the surface morphology, chemical structure, and microstructure of the UV-exposed itPP films were investigated using scanning electron microscopy, infrared spectroscopy, differential scanning calorimetry, and wide- and small-angle X-ray scattering. Photooxidative degradation was inhibited as the orientation degree of the itPP film increased. These results indicate that photooxidation likely occurs in the amorphous phase of itPP. Oriented molecular chains effectively slowed the photooxidative degradation of the itPP films. The artificial fragmentation test of UV-exposed itPP films showed that itPP films with lower crystallinity and orientation degrees were crushed into microplastics that were much smaller in size than those with higher crystallinity or orientation degrees. Photooxidation and fragmentation behaviors of itPP were studied. Photooxidation likely occurred in the amorphous regions of itPP due to the higher oxygen diffusion. Surface deterioration was observed on the UV-exposed itPP films. Pressed films exhibited much denser cracks compared to uniaxially oriented itPP films. Notably, cracks in the uniaxially oriented itPP films were formed along the direction of orientation and decreased with increasing draw ratio. The crystalline structure and oriented molecular chains notably inhibited the photooxidative degradation and fragmentation of the itPP films.
{"title":"Photooxidative degradation and fragmentation behaviors of oriented isotactic polypropylene","authors":"Yingjun An, Tomoko Kajiwara, Adchara Padermshoke, Thinh Van Nguyen, Sinan Feng, Hiroyasu Masunaga, Yutaka Kobayashi, Hiroshi Ito, Sono Sasaki, Atsuhiko Isobe, Atsushi Takahara","doi":"10.1038/s41428-023-00876-4","DOIUrl":"10.1038/s41428-023-00876-4","url":null,"abstract":"The photooxidative degradation and fragmentation behaviors of isotactic polypropylene (itPP) were simulated in laboratory after various postconditions, such as quenching, gradual cooling and drawing, using an artificial weathering machine and a blender. The crystallinity of the itPP films and orientation of the molecular chains play important roles in the photooxidation of the itPP films. Compared to quenched itPP films with the same ultraviolet (UV) exposure time, highly oriented itPP films and gradually cooled itPP films with higher crystallinity exhibited a lower rate of photooxidative degradation. To clarify the photooxidative degradation mechanism, the surface morphology, chemical structure, and microstructure of the UV-exposed itPP films were investigated using scanning electron microscopy, infrared spectroscopy, differential scanning calorimetry, and wide- and small-angle X-ray scattering. Photooxidative degradation was inhibited as the orientation degree of the itPP film increased. These results indicate that photooxidation likely occurs in the amorphous phase of itPP. Oriented molecular chains effectively slowed the photooxidative degradation of the itPP films. The artificial fragmentation test of UV-exposed itPP films showed that itPP films with lower crystallinity and orientation degrees were crushed into microplastics that were much smaller in size than those with higher crystallinity or orientation degrees. Photooxidation and fragmentation behaviors of itPP were studied. Photooxidation likely occurred in the amorphous regions of itPP due to the higher oxygen diffusion. Surface deterioration was observed on the UV-exposed itPP films. Pressed films exhibited much denser cracks compared to uniaxially oriented itPP films. Notably, cracks in the uniaxially oriented itPP films were formed along the direction of orientation and decreased with increasing draw ratio. The crystalline structure and oriented molecular chains notably inhibited the photooxidative degradation and fragmentation of the itPP films.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"56 4","pages":"379-389"},"PeriodicalIF":2.8,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41428-023-00876-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139552875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The introduction of biodegradable plastics is considered a practical approach to reducing plastic waste accumulation in the environment. Regardless of their biodegradability, plastics should be recycled to effectively utilize and circulate carbon as a resource. Herein, the use of pyrolysis was examined as a method for recycling two common biobased/biodegradable plastics: PLA and PHBH. The pyrolysis of PLA produced lactides (10.7 wt% at 400 °C), but the yield was decreased when the pyrolysis temperature was increased. The presence of steam promoted the hydrolysis of PLA: a steam concentration of 25 vol % increased, the production of lactides at 400 °C to 17.4 wt%. The pyrolysis of PHBH primarily yielded crotonic acid (30.1 wt% at 400 °C), and the yield increased with increasing pyrolysis temperature (71.8 wt% at 800 °C). Steam injection increased the hydrolysis of oligomers, resulting in a 76.1 wt% yield of crotonic acid at 600 °C with a steam concentration of 25 vol %. Thus, we determined that hydrolysis and pyrolysis progress simultaneously under a steam atmosphere, increasing the chemical feedstock recovery from PLA and PHBH. These findings may lead to the proposal of effective degradation methods for treating biobased/biodegradable plastic wastes and ways to maximize the conversion efficiency and target product yields. Steam decomposition of poly(lactic acid) (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) enhanced the recovery of chemical feedstock compared with simple pyrolysis. Steam enhanced the hydrolysis of PLA and resulted in the formation of short-chain compounds with hydroxyl end groups, and subsequent pyrolysis of them improved lactide recovery. Monomer production from PHBH was also enhanced by simultaneous hydrolysis and pyrolysis under steam decomposition.
{"title":"Characteristics of the steam degradation of poly(lactic acid) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)","authors":"Zhuze Shao, Shogo Kumagai, Yuko Saito, Toshiaki Yoshioka","doi":"10.1038/s41428-024-00883-z","DOIUrl":"10.1038/s41428-024-00883-z","url":null,"abstract":"The introduction of biodegradable plastics is considered a practical approach to reducing plastic waste accumulation in the environment. Regardless of their biodegradability, plastics should be recycled to effectively utilize and circulate carbon as a resource. Herein, the use of pyrolysis was examined as a method for recycling two common biobased/biodegradable plastics: PLA and PHBH. The pyrolysis of PLA produced lactides (10.7 wt% at 400 °C), but the yield was decreased when the pyrolysis temperature was increased. The presence of steam promoted the hydrolysis of PLA: a steam concentration of 25 vol % increased, the production of lactides at 400 °C to 17.4 wt%. The pyrolysis of PHBH primarily yielded crotonic acid (30.1 wt% at 400 °C), and the yield increased with increasing pyrolysis temperature (71.8 wt% at 800 °C). Steam injection increased the hydrolysis of oligomers, resulting in a 76.1 wt% yield of crotonic acid at 600 °C with a steam concentration of 25 vol %. Thus, we determined that hydrolysis and pyrolysis progress simultaneously under a steam atmosphere, increasing the chemical feedstock recovery from PLA and PHBH. These findings may lead to the proposal of effective degradation methods for treating biobased/biodegradable plastic wastes and ways to maximize the conversion efficiency and target product yields. Steam decomposition of poly(lactic acid) (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) enhanced the recovery of chemical feedstock compared with simple pyrolysis. Steam enhanced the hydrolysis of PLA and resulted in the formation of short-chain compounds with hydroxyl end groups, and subsequent pyrolysis of them improved lactide recovery. Monomer production from PHBH was also enhanced by simultaneous hydrolysis and pyrolysis under steam decomposition.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"56 4","pages":"455-462"},"PeriodicalIF":2.8,"publicationDate":"2024-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41428-024-00883-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139552984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：