单分子光学探针揭示易混聚合物受限纳米区域的动力学
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摘要
常规的系综研究方法显示在动力学不对称的易混聚合物中存在着受限区域,但是不能给出受限区域的分布、尺度及受限区域内的动力学分布特征等.单分子光学探针被用来探测苯乙烯高聚物与苯乙烯寡聚物形成的易混聚合物薄膜中的受限纳米区域的动力学.实验发现易混聚合物中存在转动和固定不动的两种动力学形式的单分子,指示着单分子分别耦合到苯乙烯高聚物和苯乙烯寡聚物的聚合物链片段上.转动单分子的分布揭示了易混聚合物薄膜受限区域的分布特征.受限区域的尺度被估计为其可能接近于单分子探针的尺度(约2 nm).受限纳米区域中单分子的转动关联时间的分布揭示了受限纳米区域中聚合物动力学的分布特征.实验发现在含有更高浓度的苯乙烯高聚物的混聚物薄膜中具有更快的动力学行为,从而在单分子水平上揭示了易混聚合物中的受限纳米区域的动力学.
Miscible mixtures of polymer blends have physical properties that are often linked simply to the blend composition, thus offering an inexpensive and convenient method to achieve new high performance polymers.Confinement effect has been found in various polymer blend systems by the ensemble methods, but further understanding the confinement effect still requires large efforts both in experiment and in theory. Single molecule spectroscopy has the potential to provide an in-depth insight to the dynamic information by directly coupling their reorientation to the segmental relaxation of the surrounding polymer matrix. We investigate the confinement effects in polystyrene and oligostyrene blend films by using single-molecule defocused wide-field fluorescence microscopy. According to the observation for dynamic behaviors of probe molecules in the blend films of 75 wt.% and 25 wt.% polystyrene, we find that there are two types of single molecules in the blend films: rotational molecules and immobile molecules. The experimental temperature of 296 K is between the glass transition temperature(Tg) values of two pure components and also is far from the two Tg values. At the temperature, oligostyrene component is trapped by the frozen polystyrene component, but they still move locally. Therefore, the rotational and immobile molecules should couple to the oligostyrene component and polystyrene component, respectively. The distribution of rotational single molecules reveals that the confined regions randomly distribute across miscible polymer blends. The length scale of confined region is estimated to be close to that of the probe molecule by taking into account the rotational dynamics of single molecules. The local relaxation of blend film is also investigated by the rotational correlation time which can be estimated by fitting the autocorrelation curve of 〈 cos(F)〉 with a Kohlrausch-Williams-Watts stretched exponential function. The histograms of the rotational correlation times in the blend films of 75 wt.% and 25 wt.%polystyrene are obtained respectively, which reveal the characteristic of local dynamic distribution in the confined nano-regions. We find that the dynamic behavior in the blend film of 75 wt.% polystyrene is faster than that of 25 wt.% polystyrene, indicating there is a confinement effect in the blend due to the increased constraints imposed by the polystyrene component at a higher concentration of polystyrene. All results observed in the experiment can be explained qualitatively by the self-concentration model. Our work indicates that the single molecule defocused wide-field fluorescence microscopy is a powerful tool to study the complex dynamic features in the polymer blends.
Miscible mixtures of polymer blends have physical properties that are often linked simply to the blend composition, thus offering an inexpensive and convenient method to achieve new high performance polymers.Confinement effect has been found in various polymer blend systems by the ensemble methods, but further understanding the confinement effect still requires large efforts both in experiment and in theory. Single molecule spectroscopy has the potential to provide an in-depth insight to the dynamic information by directly coupling their reorientation to the segmental relaxation of the surrounding polymer matrix. We investigate the confinement effects in polystyrene and oligostyrene blend films by using single-molecule defocused wide-field fluorescence microscopy. According to the observation for dynamic behaviors of probe molecules in the blend films of 75 wt.% and 25 wt.% polystyrene, we find that there are two types of single molecules in the blend films: rotational molecules and immobile molecules. The experimental temperature of 296 K is between the glass transition temperature(Tg) values of two pure components and also is far from the two Tg values. At the temperature, oligostyrene component is trapped by the frozen polystyrene component, but they still move locally. Therefore, the rotational and immobile molecules should couple to the oligostyrene component and polystyrene component, respectively. The distribution of rotational single molecules reveals that the confined regions randomly distribute across miscible polymer blends. The length scale of confined region is estimated to be close to that of the probe molecule by taking into account the rotational dynamics of single molecules. The local relaxation of blend film is also investigated by the rotational correlation time which can be estimated by fitting the autocorrelation curve of 〈 cos(F)〉 with a Kohlrausch-Williams-Watts stretched exponential function. The histograms of the rotational correlation times in the blend films of 75 wt.% and 25 wt.%polystyrene are obtained respectively, which reveal the characteristic of local dynamic distribution in the confined nano-regions. We find that the dynamic behavior in the blend film of 75 wt.% polystyrene is faster than that of 25 wt.% polystyrene, indicating there is a confinement effect in the blend due to the increased constraints imposed by the polystyrene component at a higher concentration of polystyrene. All results observed in the experiment can be explained qualitatively by the self-concentration model. Our work indicates that the single molecule defocused wide-field fluorescence microscopy is a powerful tool to study the complex dynamic features in the polymer blends.
引文
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[13]Zhao J S,Ediger M D,Sun Y,Yu L 2009 Macro-molecules 426777
[14]Yang H X,Green P F 2013 Macromolecules 46 9390
[15]Sharma R P,Green P F 2017 Macromolecules 50 6617
[16]Harmandaris V A,Kremer K,Floudas G 2013 Phys.Rev.Lett 110 165701
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[22]Zhao L,Wang C L,Liu J,Wen B H,Tu Y S,Wang Z W,Fang H P 2014 Phys.Rev.Lett.112 078301
[23]Li L D,Ye A N,Zhou S L,Zhang X H,Yang Z H 2019 Acta Phys.Sin.68 026402(in Chinese)[李灵栋,叶安娜,周胜林,张晓华,杨朝晖2019物理学报68 026402]
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[26]Yuan H,Gaiduk A,Siekierzycka J R,Fujiyoshi S,Matsushita M,Nettels D,Schuler B,Seidel C A M,Orrit M 2015 Phys.Chem.Chem.Phys.17 6532
[27]Shi Y,Li Y,Zhou H T,Chen R Y,Zhang G F,Qin C B,Gao Y,Xiao L T,Jia S T 2019 Acta Phys.Sin.68 048201(in Chinese)[石莹,李耀,周海涛,陈瑞云,张国峰,秦成兵,高岩,肖连团,贾锁堂2019物理学报68 048201]
[28]Qin Y Q,Chen R Y,Shi Y,Zhou H T,Zhang G F,Qin C B,Gao Y,Xiao L T,Jia S T 2017 Acta Phys.Sin.66 248201(in Chinese)[秦亚强,陈瑞云,石莹,周海涛,张国峰,秦成兵,高岩,肖连团,贾锁堂2017物理学报66 248201]
[29]Zhang G F,Xiao L T,Zhang F,Wang X B,Jia S T 2010Phys.Chem.Chem.Phys.12 2308
[30]Zheng Z L,Kuang F Y,Zhao J 2010 Macromolecules 43 3165
[31]Zhang G F,Zhang F,Cheng F Y,Sun J H,Xiao L T,Jia S T2009 Acta Phys.Sin.58 2364(in Chinese)[张国峰,张芳,程峰钰,孙建虎,肖连团,贾锁堂2009物理学报58 2364]
[32]Hutchison J A,Uji-i H,Deres A,Vosch T,Rocha S,Muller S,Bastian A A,Enderlein J,Nourouzi H,Li C,Herrmann A,Mullen K,de Schryver F,Hofkens J 2014 Nat.Nanotechnol. 9131
[33]Krajnik B,Chen J W,Watson M A,Cockroft S L,Feringa B L,Hofkens J 2017 J.Am.Chem.Soc.139 7156
[34]Deres A,Floudas G A,Mullen K,van der Auweraer M,de Schryver F,Enderlein J,Uji-i H,Hofkens J 2011Macromolecules 44 9703
[35]Dedecker P,Muls B,Deres A,Uji-i H,Hotta J,Sliwa M,Soumillion J P,Mullen K,Enderlein J,Hofkens J 2009 Adv.Mater.21 1079
[36]Bin L,Zhang G F,Jing M Y,Chen R Y,Qin C B,Gao Y,Xiao L T,Jia S T 2016 Acta Phys.Sin.68 218201(in Chinese)[李斌,张国峰,景明勇,陈瑞云,秦成兵,高岩,肖连团,贾锁堂2016物理学报68 218201]
[2]Maranas J K 2007 Curr.Opin.Colloid Interface Sci.12 29
[3]Colmenero J,Arbe A 2007 Soft Matter 3 1474
[4]Heriot S Y,Jones R A L 2005 Nat.Mater.4 782
[5]Ebbens S,Hodgkinson R,Parnell A J,Dunbar A,Martin S J,Top ham P D,Clarke N,Howse J R 2011 A CS Nano 5 5124
[6]Gambino T,Alegria A,Arbe A,Colmenero J,Malicki N,Dronet S,Schnell B,Lohstroh W,Nemkovski K 2018Macromolecules 51 6692
[7]Evans C M,Narayanan S,Jiang Z,Torkelson J M 2012 Phys.Rev.Lett.51 038302
[8]Gooneie A,Schuschnigg S,Holzer C 2017 Polymers 9 16
[9]Li D M,Yuan X J,Zhou J Q 2013 Acta Phys.Sin.62 167202(in Chinese)[李冬梅,袁晓娟,周加强2013物理学报62167202]
[10]Yuan X J,Yuan H M,Zhang C Q,Wang W J,Yu Y X,Liu D S 2015 Acta Phys.Sin.64 067201(in Chinese)[袁晓娟,袁慧敏,张成强,王文静,于元勋,刘德胜2015物理学报64067201]
[11]Evans C M,Torkelson J M 2012 Polymer 53 6118
[12]Dudowicz J,Douglas J F,Freed K F 2014 J.Chem.Phys.140 244905
[13]Zhao J S,Ediger M D,Sun Y,Yu L 2009 Macro-molecules 426777
[14]Yang H X,Green P F 2013 Macromolecules 46 9390
[15]Sharma R P,Green P F 2017 Macromolecules 50 6617
[16]Harmandaris V A,Kremer K,Floudas G 2013 Phys.Rev.Lett 110 165701
[17]Nassar S F,Domenek S,Guinault A,Stoclet G,Delpouve N,Sollogoub C 2018 Macromolecules 51 128
[18]Harmandaris V,Doxastakis M 2013 J.Chem.Phys.139034904
[19]Liu W J,Bedrov D,Kumar S K,Veytsman B,Colby R H2009 Phys.Rev.Lett.103 037801
[20]Lodge T P,McLeish T C B 2000 Macromolecules 33 5278
[21]Adrjanowicz K,Kaminski K,Tarnacka M,Szklarz G,Paluch M 2017 J.Phys.Chem.Lett.8 696
[22]Zhao L,Wang C L,Liu J,Wen B H,Tu Y S,Wang Z W,Fang H P 2014 Phys.Rev.Lett.112 078301
[23]Li L D,Ye A N,Zhou S L,Zhang X H,Yang Z H 2019 Acta Phys.Sin.68 026402(in Chinese)[李灵栋,叶安娜,周胜林,张晓华,杨朝晖2019物理学报68 026402]
[24]Orrit M,Ha T,Sandoghdar V 2014 Chem.Soc.Rev.43 973
[25]Li Y,Chen R,Zhou H, Shi Y,Qin C,Gao Y,Zhang G,Gao Y,Xiao L,Jia S 2018 J.Phys.Chem.Lett. 9 5207
[26]Yuan H,Gaiduk A,Siekierzycka J R,Fujiyoshi S,Matsushita M,Nettels D,Schuler B,Seidel C A M,Orrit M 2015 Phys.Chem.Chem.Phys.17 6532
[27]Shi Y,Li Y,Zhou H T,Chen R Y,Zhang G F,Qin C B,Gao Y,Xiao L T,Jia S T 2019 Acta Phys.Sin.68 048201(in Chinese)[石莹,李耀,周海涛,陈瑞云,张国峰,秦成兵,高岩,肖连团,贾锁堂2019物理学报68 048201]
[28]Qin Y Q,Chen R Y,Shi Y,Zhou H T,Zhang G F,Qin C B,Gao Y,Xiao L T,Jia S T 2017 Acta Phys.Sin.66 248201(in Chinese)[秦亚强,陈瑞云,石莹,周海涛,张国峰,秦成兵,高岩,肖连团,贾锁堂2017物理学报66 248201]
[29]Zhang G F,Xiao L T,Zhang F,Wang X B,Jia S T 2010Phys.Chem.Chem.Phys.12 2308
[30]Zheng Z L,Kuang F Y,Zhao J 2010 Macromolecules 43 3165
[31]Zhang G F,Zhang F,Cheng F Y,Sun J H,Xiao L T,Jia S T2009 Acta Phys.Sin.58 2364(in Chinese)[张国峰,张芳,程峰钰,孙建虎,肖连团,贾锁堂2009物理学报58 2364]
[32]Hutchison J A,Uji-i H,Deres A,Vosch T,Rocha S,Muller S,Bastian A A,Enderlein J,Nourouzi H,Li C,Herrmann A,Mullen K,de Schryver F,Hofkens J 2014 Nat.Nanotechnol. 9131
[33]Krajnik B,Chen J W,Watson M A,Cockroft S L,Feringa B L,Hofkens J 2017 J.Am.Chem.Soc.139 7156
[34]Deres A,Floudas G A,Mullen K,van der Auweraer M,de Schryver F,Enderlein J,Uji-i H,Hofkens J 2011Macromolecules 44 9703
[35]Dedecker P,Muls B,Deres A,Uji-i H,Hotta J,Sliwa M,Soumillion J P,Mullen K,Enderlein J,Hofkens J 2009 Adv.Mater.21 1079
[36]Bin L,Zhang G F,Jing M Y,Chen R Y,Qin C B,Gao Y,Xiao L T,Jia S T 2016 Acta Phys.Sin.68 218201(in Chinese)[李斌,张国峰,景明勇,陈瑞云,秦成兵,高岩,肖连团,贾锁堂2016物理学报68 218201]