Transport of monomer from droplets to growing latex particles in emulsion polymerization in general is assumed to proceed via diffusion through the aqueous phase. Especially in miniemulsion polymerizations the direct transfer of very hydrophobic species from droplet to droplet is assumed to also proceed via collisions. Amongst the hydrophobic species where this is shown to play a role are monomers, initiators, inhibitors and (catalytic) chain transfer agents. It is well known that the reactor geometry and the stirring speed can have a profound effect on emulsion polymerizations. The 1972 paper of Nomura on the effect of stirring on emulsion polymerization is cited more than 100 times and until today keeps scientists intrigued. Diffusion limitations of monomer going from the droplet into the aqueous phase can occur for very hydrophobic monomers. The alternative route of transport via collisions is often not considered. In this perspective, paper will discuss the evidence for collision based transfer in miniemulsion polymerization and also consider whether collision based monomer transport can play a role in regular emulsion polymerizations.
{"title":"Monomer Transport by Collisions in (Mini) Emulsion Polymerization, a Personal Perspective","authors":"Alexander M. van Herk","doi":"10.1002/mren.202400013","DOIUrl":"https://doi.org/10.1002/mren.202400013","url":null,"abstract":"Transport of monomer from droplets to growing latex particles in emulsion polymerization in general is assumed to proceed via diffusion through the aqueous phase. Especially in miniemulsion polymerizations the direct transfer of very hydrophobic species from droplet to droplet is assumed to also proceed via collisions. Amongst the hydrophobic species where this is shown to play a role are monomers, initiators, inhibitors and (catalytic) chain transfer agents. It is well known that the reactor geometry and the stirring speed can have a profound effect on emulsion polymerizations. The 1972 paper of Nomura on the effect of stirring on emulsion polymerization is cited more than 100 times and until today keeps scientists intrigued. Diffusion limitations of monomer going from the droplet into the aqueous phase can occur for very hydrophobic monomers. The alternative route of transport via collisions is often not considered. In this perspective, paper will discuss the evidence for collision based transfer in miniemulsion polymerization and also consider whether collision based monomer transport can play a role in regular emulsion polymerizations.","PeriodicalId":18052,"journal":{"name":"Macromolecular Reaction Engineering","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208552","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study investigates polyaniline (PANI) for its sensing characteristics for detecting acetaldehyde. Pristine PANI is further modified in two ways to improve its sensing capabilities: 1) addition of a side chain (i.e., two methyl groups) to form poly (2,5‐dimethylaniline), 2) addition of small amounts of metal oxide dopant (In2O3 in this case) to PANI. All the materials are evaluated for their sensing characteristics with respect to both sensitivity and selectivity. The sensitivity of PANI toward acetaldehyde is found to improve with both types of modification (i.e., poly (2,5‐dimethylaniline) and PANI doped with different wt.% of In2O3). However, upon evaluating selectivity toward acetaldehyde using binary and ternary gas mixtures, pristine PANI exhibited higher selectivity compared to its modified counterparts.
本研究探讨了聚苯胺 (PANI) 检测乙醛的传感特性。原始 PANI 可通过两种方式进一步改性，以提高其传感能力：1) 添加侧链（即两个甲基）形成聚（2,5-二甲基苯胺），2) 在 PANI 中添加少量金属氧化物掺杂剂（本例中为 In2O3）。我们对所有材料的传感特性进行了评估，包括灵敏度和选择性。结果发现，PANI 对乙醛的灵敏度随着两种改性类型（即聚（2,5-二甲基苯胺）和掺杂不同重量百分比 In2O3 的 PANI）的增加而提高。不过，在使用二元和三元气体混合物评估对乙醛的选择性时，原始 PANI 的选择性高于其改性后的同类产品。
{"title":"Tailoring Polyaniline for Improved Acetaldehyde Detection","authors":"Bhoomi Het Mavani, Alexander Penlidis","doi":"10.1002/mren.202400018","DOIUrl":"https://doi.org/10.1002/mren.202400018","url":null,"abstract":"This study investigates polyaniline (PANI) for its sensing characteristics for detecting acetaldehyde. Pristine PANI is further modified in two ways to improve its sensing capabilities: 1) addition of a side chain (i.e., two methyl groups) to form poly (2,5‐dimethylaniline), 2) addition of small amounts of metal oxide dopant (In<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> in this case) to PANI. All the materials are evaluated for their sensing characteristics with respect to both sensitivity and selectivity. The sensitivity of PANI toward acetaldehyde is found to improve with both types of modification (i.e., poly (2,5‐dimethylaniline) and PANI doped with different wt.% of In<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>). However, upon evaluating selectivity toward acetaldehyde using binary and ternary gas mixtures, pristine PANI exhibited higher selectivity compared to its modified counterparts.","PeriodicalId":18052,"journal":{"name":"Macromolecular Reaction Engineering","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shen Li, Zhong‐Xin Liu, Yin‐Ning Zhou, Zheng‐Hong Luo
The effect of solvents on kinetic parameters of anionic polymerization is complex and a comprehensive theoretical study has been rare. In this work, four solvent polarity descriptors (i.e., polarizability, dipole moment, nucleophilic index, electrophilic index) are correlated with solvent parameters (Ea, A, ΔH‡, and ΔS‡) by multiple linear regression using the Catalan linear free‐energy relationship (LFER) equation for the anionic polymerization of styrene. The results show that Ea, ΔH‡, and ΔS‡ have a low correlation with dipole moment, whereas A is strongly correlated with dipole moment. Given the fact that the larger A the larger effective collision frequency Z, it is hypothesized that in polar solvents, the polymer chains are more extended, enabling more effective collisions between monomers and active anionic species during polymerization. In contrast, in nonpolar solvents, the polymer chains collapse, making it more difficult for the monomer to be inserted into the ion pairs. Subsequently, n‐pentane and tetrahydrofuran are chosen as representatives to confirm this conjecture by molecular simulations. Lastly, Ea, A and kp are predicted for 173 solvents using well‐established descriptive relationships.
溶剂对阴离子聚合动力学参数的影响非常复杂，目前还很少有全面的理论研究。本研究采用加泰罗尼亚线性自由能关系（LFER）方程，通过多元线性回归，将苯乙烯阴离子聚合反应中的四个溶剂极性描述因子（即极化性、偶极矩、亲核指数、亲电指数）与溶剂参数（Ea、A、ΔH‡ 和 ΔS‡）相关联。结果表明，Ea、ΔH‡ 和 ΔS‡ 与偶极矩的相关性较低，而 A 与偶极矩的相关性较高。鉴于 A 越大，有效碰撞频率 Z 越大这一事实，可以推测在极性溶剂中，聚合物链延伸得越长，聚合过程中单体和活性阴离子物质之间的碰撞就越有效。相反，在非极性溶剂中，聚合物链会塌陷，使单体更难插入离子对中。随后，我们选择了正戊烷和四氢呋喃作为代表，通过分子模拟来证实这一猜想。最后，利用成熟的描述关系预测了 173 种溶剂的 Ea、A 和 kp。
{"title":"Determining the Kinetic and Thermodynamic Parameters of Anionic Polymerization of Styrene Using Linear Free‐Energy Relationship","authors":"Shen Li, Zhong‐Xin Liu, Yin‐Ning Zhou, Zheng‐Hong Luo","doi":"10.1002/mren.202400021","DOIUrl":"https://doi.org/10.1002/mren.202400021","url":null,"abstract":"The effect of solvents on kinetic parameters of anionic polymerization is complex and a comprehensive theoretical study has been rare. In this work, four solvent polarity descriptors (i.e., polarizability, dipole moment, nucleophilic index, electrophilic index) are correlated with solvent parameters (Ea, A, ΔH‡, and ΔS‡) by multiple linear regression using the Catalan linear free‐energy relationship (LFER) equation for the anionic polymerization of styrene. The results show that Ea, ΔH‡, and ΔS‡ have a low correlation with dipole moment, whereas A is strongly correlated with dipole moment. Given the fact that the larger A the larger effective collision frequency Z, it is hypothesized that in polar solvents, the polymer chains are more extended, enabling more effective collisions between monomers and active anionic species during polymerization. In contrast, in nonpolar solvents, the polymer chains collapse, making it more difficult for the monomer to be inserted into the ion pairs. Subsequently, n‐pentane and tetrahydrofuran are chosen as representatives to confirm this conjecture by molecular simulations. Lastly, Ea, A and kp are predicted for 173 solvents using well‐established descriptive relationships.","PeriodicalId":18052,"journal":{"name":"Macromolecular Reaction Engineering","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141922999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A rationale for droplet nucleation during inverse emulsion polymerization (IEP) (reported by previous investigators) is proposed. Based on the idea that smaller monomer droplets are nucleated into polymer particles, while larger droplets serve as reservoirs for monomer (as in a micellar nucleation mechanism) the question of possible monomer‐transport limitation during polymerization is explored.
{"title":"On the Mechanism of Nucleation and Monomer Transport in Inverse Emulsion Polymerization","authors":"F. Joseph Schork","doi":"10.1002/mren.202400017","DOIUrl":"https://doi.org/10.1002/mren.202400017","url":null,"abstract":"A rationale for droplet nucleation during inverse emulsion polymerization (IEP) (reported by previous investigators) is proposed. Based on the idea that smaller monomer droplets are nucleated into polymer particles, while larger droplets serve as reservoirs for monomer (as in a micellar nucleation mechanism) the question of possible monomer‐transport limitation during polymerization is explored.","PeriodicalId":18052,"journal":{"name":"Macromolecular Reaction Engineering","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141944321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shota Nakayama, Keishi Suga, Tatsuya Kamata, Kanako Watanabe, Hikaru Namigata, Tom A. J. Welling, Daisuke Nagao
Polydiacetylene (PDA) is a kind of photopolymerizable polymer, which exhibits a unique color transition in response to external stimuli such as heat, pH, and solvent. PDAs are attractive as eye‐detection stimulus sensors with excellent time performance; however, the sensitivity of PDAs should be improved. Considering the biological membrane‐like structure of diacetylene (DA) vesicles, their modification by incorporating membrane lipids (e.g., diacylphosphocholine, PC) can be used to control the membrane fluidity, and consequently molecular ordering of DAs in the vesicle. Inspired by biological membrane systems, lipid vesicles are employed as platforms to generate PDA, and essential factors that influence the sensitivity of PDA are investigated. By lowering the polymerization temperature, the generation of PDA becomes slower, while the sensitivity improves. By adding PCs at the molar ratio of lipid:DA = 1:1, the sensitivity of PDA can be varied: the PCs with lower phase transition temperatures (Tm) made PDA insensitive, while the PCs with higher Tm improved the sensitivity as compared to pure poly(PCDA). It is concluded that the photopolymerization of DAs with a lower membrane fluidity induces highly sensitive PDA, while the photopolymerization of DAs with a higher membrane fluidity induces insensitive PDA with robustness toward stimuli.
聚二乙炔（PDA）是一种可光聚合的聚合物，在热量、pH 值和溶剂等外界刺激下会呈现出独特的颜色转变。PDA 作为眼球探测刺激传感器具有极佳的时间性能，但其灵敏度有待提高。考虑到双乙炔（DA）囊泡具有类似生物膜的结构，通过加入膜脂质（如二酰基磷酸胆碱，PC）对其进行修饰可用于控制膜的流动性，从而控制囊泡中 DA 的分子排序。受生物膜系统的启发，我们利用脂质囊泡作为生成 PDA 的平台，并研究了影响 PDA 灵敏度的关键因素。通过降低聚合温度，PDA 的生成速度变慢，而灵敏度提高。通过以脂质：DA = 1:1 的摩尔比添加多氯化萘，可改变 PDA 的灵敏度：相变温度（Tm）较低的多氯化萘会使 PDA 变得不灵敏，而相变温度（Tm）较高的多氯化萘与纯聚 PCDA 相比则会提高灵敏度。结论是，膜流动性较低的 DAs 光聚合可诱导出高灵敏度的 PDA，而膜流动性较高的 DAs 光聚合可诱导出不灵敏的 PDA，并对刺激具有稳健性。
{"title":"Bio‐Inspired Polydiacetylene Vesicles for Controlling Stimulus Sensitivity","authors":"Shota Nakayama, Keishi Suga, Tatsuya Kamata, Kanako Watanabe, Hikaru Namigata, Tom A. J. Welling, Daisuke Nagao","doi":"10.1002/mren.202400016","DOIUrl":"https://doi.org/10.1002/mren.202400016","url":null,"abstract":"Polydiacetylene (PDA) is a kind of photopolymerizable polymer, which exhibits a unique color transition in response to external stimuli such as heat, pH, and solvent. PDAs are attractive as eye‐detection stimulus sensors with excellent time performance; however, the sensitivity of PDAs should be improved. Considering the biological membrane‐like structure of diacetylene (DA) vesicles, their modification by incorporating membrane lipids (e.g., diacylphosphocholine, PC) can be used to control the membrane fluidity, and consequently molecular ordering of DAs in the vesicle. Inspired by biological membrane systems, lipid vesicles are employed as platforms to generate PDA, and essential factors that influence the sensitivity of PDA are investigated. By lowering the polymerization temperature, the generation of PDA becomes slower, while the sensitivity improves. By adding PCs at the molar ratio of lipid:DA = 1:1, the sensitivity of PDA can be varied: the PCs with lower phase transition temperatures (<jats:italic>T</jats:italic><jats:sub>m</jats:sub>) made PDA insensitive, while the PCs with higher <jats:italic>T</jats:italic><jats:sub>m</jats:sub> improved the sensitivity as compared to pure poly(PCDA). It is concluded that the photopolymerization of DAs with a lower membrane fluidity induces highly sensitive PDA, while the photopolymerization of DAs with a higher membrane fluidity induces insensitive PDA with robustness toward stimuli.","PeriodicalId":18052,"journal":{"name":"Macromolecular Reaction Engineering","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141871416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Annika Klinkert, Zoe Friedrich, Elisabeth Glatt, Wolfgang Augustin, Stephan Scholl
Front Cover: The deposition process during emulsion polymerization is classified as particulate and reaction fouling. The deposited material is composed of latex particles and emulsifier with particle size and number depending on the respective equilibrium composition of the fluid phase. The figure shows the deposition of latex particles after a reaction time of 240 minutes. Further details can be found in article 2300057 by Wolfgang Augustin and co-workers.
封面：乳液聚合过程中的沉积过程分为微粒污垢和反应污垢。沉积物由胶乳颗粒和乳化剂组成，颗粒大小和数量取决于流体相各自的平衡组成。图中显示了反应 240 分钟后胶乳颗粒的沉积情况。更多详细信息，请参阅 Wolfgang Augustin 及其合作者撰写的文章 2300057。
{"title":"Polymer Versus Polymerization Fouling: Basic Deposition Mechanisms During Emulsion Polymerization by the Example of a Vinyl Acetate and Versa 10 Copolymer","authors":"Annika Klinkert, Zoe Friedrich, Elisabeth Glatt, Wolfgang Augustin, Stephan Scholl","doi":"10.1002/mren.202470005","DOIUrl":"https://doi.org/10.1002/mren.202470005","url":null,"abstract":"<p><b>Front Cover</b>: The deposition process during emulsion polymerization is classified as particulate and reaction fouling. The deposited material is composed of latex particles and emulsifier with particle size and number depending on the respective equilibrium composition of the fluid phase. The figure shows the deposition of latex particles after a reaction time of 240 minutes. Further details can be found in article 2300057 by Wolfgang Augustin and co-workers.\u0000\u0000 <figure>\u0000 <div><picture>\u0000 <source></source></picture><p></p>\u0000 </div>\u0000 </figure></p>","PeriodicalId":18052,"journal":{"name":"Macromolecular Reaction Engineering","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mren.202470005","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141425090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In vinyl/divinyl copolymerization, a crosslink is formed by the reaction between an active center and a pendant double bond. When both the active center and the pendant double bond are located within the same polymer molecule, the cyclization occurs, which is ineffective for growth in molecular weight. In the present model, the network dimension theory is applied to estimate the mean‐square radius of gyration for the growing polymer molecule, which is used to account for the enrichment effect of pendant double bonds around the active center for the cyclization reaction. The model is applied to the miniemulsion copolymerization, and both conventional free‐radical polymerization and ideal living polymerization are considered. Some of important characteristics of network architecture formed in these two types of polymerization mechanisms that cannot be predicted based on the classical chemical kinetics can be reproduced by the model, such unique characteristics as the pendant double bonds are consumed from the beginning of polymerization in the conventional free‐radical polymerization but not so in the living polymerization. The present model provides useful insights into the size and structural dependent network formation kinetics without relying on the lattice model.This article is protected by copyright. All rights reserved
{"title":"Application of Network Dimension Theory to the Kinetics of Nanogel Formation in Miniemulsion Vinyl/Divinyl Copolymerization: Free‐Radical and Living Polymerization","authors":"H. Tobita","doi":"10.1002/mren.202400014","DOIUrl":"https://doi.org/10.1002/mren.202400014","url":null,"abstract":"In vinyl/divinyl copolymerization, a crosslink is formed by the reaction between an active center and a pendant double bond. When both the active center and the pendant double bond are located within the same polymer molecule, the cyclization occurs, which is ineffective for growth in molecular weight. In the present model, the network dimension theory is applied to estimate the mean‐square radius of gyration for the growing polymer molecule, which is used to account for the enrichment effect of pendant double bonds around the active center for the cyclization reaction. The model is applied to the miniemulsion copolymerization, and both conventional free‐radical polymerization and ideal living polymerization are considered. Some of important characteristics of network architecture formed in these two types of polymerization mechanisms that cannot be predicted based on the classical chemical kinetics can be reproduced by the model, such unique characteristics as the pendant double bonds are consumed from the beginning of polymerization in the conventional free‐radical polymerization but not so in the living polymerization. The present model provides useful insights into the size and structural dependent network formation kinetics without relying on the lattice model.This article is protected by copyright. All rights reserved","PeriodicalId":18052,"journal":{"name":"Macromolecular Reaction Engineering","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141362715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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