It gives us great pleasure to see this special edition of Macromolecular Reaction Engineering (MREN) dedicated to our colleague and friend Professor Joao Soares on the occasion of his 60^th birthday. Jo's contribution to the field of polymer reaction engineering continues to be outstanding, beginning with the work he did with the great Archie Hamielec in the early 1990s on modelling of polyolefins, and where he first fell in (platonic) love with Stockmayer and his bivariate distributions. After graduating from McMaster University in 1995 he moved first to Waterloo University where he established himself as a world class researcher in the field of catalytic olefin polymerization. In 2013 he moved to the University of Alberta, and significantly expanded his areas of interested to include many different areas, applying his unique approach to PRE problem solving to study water soluble polymers, structure property relationships, and nanocomposites as well. Over the course of these past 25 years Jo has distinguished himself as a world leader in the application of Polymer Reaction Engineering (PRE) tools. Of course, we are looking forward to at least a couple more decades of interesting things from him, but this is a nice opportunity to acknowledge his contributions, and to take at look at how things are changing.

Over the years, we have heard many comments and opinions about how mature PRE has become and that it is now a mature field where only incremental work is being done. We think that the papers published in this special issue go a long way to dispelling these points of view. But first we can ask ourselves what polymer reaction engineering is (and is not!). There is of course no one, obvious answer to this question, and different people will have different points of view. However, in a broad sense one can think of polymer reaction engineering as an approach to understanding and quantifying the relationship between reaction conditions, the reactor environment and the properties of the resulting polymer. This involves modelling of polymerisation kinetics, the estimation of rate constants, active centre concentrations, and reaction pathways. It includes understanding residence time distributions and population balances as well as non‐ideal thermodynamics and how the composition in the reactor influences the concentration at the polymerization site. And it means going beyond modelling of course; developing experimental tools like hardware and software sensors, experimental methods to look at polymer properties such as chain entanglements or studying the fragmentation of polymerisation catalysts. Lastly, it can even go as far as developing manufacturing strategies and processes, based on mathematical approaches and software tools, for advanced process control methods to control polymer properties.

In a previous special issue of MREN we honoured the work of some outstanding engineers who pioneered the study of PRE in North America, Archie Hamielec, Harmon Ray and Charlie Cozewith. In Europe some of the names that spring to mind as pioneers of PRE also include Hans Gerens and Karl Heinz Reichert. All of who were largely responsible for helping to develop and promote this version of PRE.

It is somewhat of a cliché, but nonetheless true to say that as time moves on, progress is indeed made on certain issues, and specific problems are solved. For instance, it is probably fair to say that we know how to model the polymerisation of styrene in the melt phase! However, some problems persist – how many of the metal atoms in a Ziegler‐Natta catalyst are truly active (and how might this change with time, conditions, etc.)? How can we predict solubilities in complex systems? Will we ever develop a means of predicting the Tromsdorff effect à priori? Furthermore, societal needs are constantly evolving, and we are called upon to think about things like the ecodesign of polymeric materials, (bio)degradation of polymers and their recycling (and rightly so). As we understand better how to make and characterise complex structures, composite materials (either made in the reactor or post‐reactor in reactive extrusion for example) are more and more in demand. Moreover, the strategies to integrate these understandings with advanced process control methods will be needed.

However, we could argue that it is precisely because the “targets” are moving and not all problems have been solved that polymer reaction engineering remains pertinent. If we consider some of the articles in the current issue dedicated to Jo Soares, this is quite apparent. A very nice article from Alex Penlidis's group demonstrates how to apply a fundamental PRE approach to the development of new materials for a specific application. Other contributions do the same but for polymers that incorporate biomaterials. There are contributions showing new developments in the control of material properties by catalyst modification, and an experimental study on catalyst fragmentation to help us better under this complex phenomenon. An article from POLYMAT discussed the importance of polymer characterisation, and another paper looks at structure‐property relationships using a basic PRE approach. We also see some new modelling and new experimental tools for the study of olefin polymerisation, as well as an experimental paper on the impact of non‐ideal thermodynamics in ethylene polymerization. All of these are new topics and applications, but ones that rely on the use of PRE tools that we can all identify with.

So, much like our friend Jo Soares, the field is changing and evolving, and while it too might look a bit old from the outside, there is still lots of life and exciting developments to come from the field of Polymer Reaction Engineering.

它给了我们非常高兴看到的这款特别版的高分子反应工程奉献给我们的同事和朋友若昂·苏亚雷斯教授在他的60之际（MREN）^日生日。Jo在聚合物反应工程领域的贡献一直是杰出的，从1990年代初他与伟大的Archie Hamielec在聚烯烃建模方面的工作开始，到他最初对Stockmayer及其双变量分布的热爱。1995年从麦克马斯特大学（McMaster University）毕业后，他首先搬到了滑铁卢大学（Waterloo University），在那里他成为催化烯烃聚合领域的世界级研究人员。2013年，他移居到阿尔伯塔大学，并将他感兴趣的领域显着扩展到许多不同领域，将他独特的方法应用于PRE问题解决中，研究了水溶性聚合物，结构性质关系以及纳米复合材料。在过去的25年中，Jo在聚合物反应工程（PRE）工具的应用领域一直处于世界领先地位。当然，我们期待着他至少有几十年的有趣经历，但这是一个很好的机会，可以感谢他的贡献，并了解事物的变化。

多年来，我们听到了许多关于PRE的成熟程度的评论和意见，而现在PRE是一个成熟的领域，仅在进行增量工作。我们认为，本期特刊上发表的论文对消除这些观点大有帮助。但是首先我们可以问自己什么是聚合物反应工程（不是！）。当然，没有人对此问题有明显的答案，不同的人会有不同的观点。但是，从广义上讲，人们可以将聚合物反应工程学视为一种理解和量化反应条件，反应器环境和所得聚合物性能之间关系的方法。这涉及到聚合动力学建模，速率常数，活性中心浓度和反应途径的估计。它包括了解停留时间分布和种群平衡以及不理想的热力学，以及反应器中的组成如何影响聚合部位的浓度。这当然意味着要超越建模。开发诸如硬件和软件传感器之类的实验工具，研究诸如链缠结之类的聚合物特性的实验方法，或研究聚合催化剂的断裂。最后，它甚至可以扩展到基于数学方法和软件工具的制造策略和过程的开发，以控制聚合物特性的高级过程控制方法。

在MREN的上期特刊中，我们对在北美研究PRE的一些杰出工程师，Archie Hamielec，Harmon Ray和Charlie Cozewith的工作表示敬意。在欧洲，作为PRE的先驱者想到的一些名字还包括Hans Gerens和Karl Heinz Reichert。所有负责开发和推广此PRE版本的人都负有主要责任。

这有点陈词滥调，但是可以说，随着时间的流逝，在某些问题上确实取得了进展，并且解决了特定的问题。例如，可以公平地说我们知道如何模拟熔融相中苯乙烯的聚合反应！但是，仍然存在一些问题–齐格勒-纳塔催化剂中有多少个金属原子真正具有活性（以及随着时间，条件等的变化，该如何变化）？我们如何预测复杂系统中的溶解度？我们是否会开发一种预测Tromsdorff效应的方法？此外，社会需求也在不断发展，我们被要求思考诸如高分子材料的生态设计，高分子的（生物）降解及其回收（正确的做法）之类的事情。随着我们更好地了解如何制作和表征复杂的结构，对复合材料（例如在反应器中或在反应挤出中的后反应器中制造）的需求越来越大。而且，将需要将这些理解与先进的过程控制方法相结合的策略。

但是，我们可以争辩说，正是由于“目标”正在移动，并且并非所有问题都已解决，聚合物反应工程仍然是相关的。如果我们考虑本期中有关Jo Soares的某些文章，这是显而易见的。Alex Penlidis小组的一篇很好的文章演示了如何将基本的PRE方法应用于特定应用的新材料开发。除了包含生物材料的聚合物外，其他贡献也相同。有贡献显示了通过催化剂改性控制材料性能的新进展，以及对催化剂裂解的实验研究，以帮助我们更好地应对这种复杂现象。POLYMAT的一篇文章讨论了聚合物表征的重要性，另一篇论文则使用基本的PRE方法研究结构与属性的关系。我们还看到了一些用于烯烃聚合研究的新模型和新实验工具，以及关于非理想热力学对乙烯聚合影响的实验论文。所有这些都是新的主题和应用程序，但是都依赖于我们都可以识别的PRE工具的使用。

因此，就像我们的朋友Jo Soares一样，该领域正在发生变化和发展，尽管从外部看，它看起来也有些陈旧，但聚合物反应工程领域仍然有很多生命和令人振奋的发展。