A Brief Overview of Polymers Science and Technology, in Spain

This Special Issue State-of-the-Art on Polymer Science and Technology in Spain is comprised of a collection of 42 publications/contributions related to very different topics undertaken by the numerous research groups working in Spain in Polymer Science and Technology. This monograph collects the contributions of more than 200 different authors from 24 different national Institutions (>30 different centers/departments) from Universities and CSIC centers distributed throughout the whole of Spain. Two-thirds of the contributions to this Special Issue arise from Institutional collaborations, half of which are international collaborations with European research groups and the other half with other international research groups outside Europe including China, Australia or United States of America among others. This brief overview communication provides a general overview of the research lines in Polymer Science and Technology covered in Spain and show most of the representative polymer groups and their distribution throughout Spain. Most of Spanish polymer groups belong to the Grupo Especializado de Polímeros (GEP) being part of the European Polymer Federation (EPF). It also shows how Spanish science about polymers is positioned at European level.


Introduction
Even if polymer science and technology in Spain started later than in other European countries, nowadays polymers have reached a good position in science and technology rankings all over the world. The creation of two research centers exclusively devoted to polymer research and the development of a high number of polymer research groups in most of the 50 public universities, together with the great number of national and multinational polymer companies established and disseminated throughout Spain, have contributed to important advances in polymer science. On occasion of the 100 years anniversary of Polymer Science in 2020, the journal Anales de Química of the Spanish Royal Chemistry Society (RSEQ) has recently published a paper in which the beginnings of polymer science in Spain, which date back to 1947, and the chronological evolution on academia and industry, are documented [1]. Until the 1980s, research groups were funded by their own institutions and/or private companies, research was highly compartmentalized, and researchers practically exclusively worked on very specific topics. This was also the case for other researchers working in different fields other than polymer science [1,2]. It is the period 1980-1990, when new and strong research groups emerged, which resulted in a great expansion of polymers in Spain. In 1985, there was an important milestone: the creation (irruption) of the National Materials Program from the Spanish Ministry of Education and Science and the integration of polymers within the materials research community. As a result, research projects started to be competitive, polymer research groups became more numerous and polymer projects had a relatively high success rate within the division of materials science. Since then, numerous polymer topics have been covered within the research groups, which are distributed throughout Spain, with two important focuses in the Autonomous Community of the Basque Country (CAPV) and the Autonomous Community of Madrid (CAM) and rapid increase in contributions from other autonomous communities, such as, Valencia, Catalonia, Castille-León and Andalusía. During this time, many existing research groups have been consolidated while new and strong polymer groups have emerged.
In the 1990s, another important milestone occurred, the launch of the Europe-wide Framework Programs for research where Spanish laboratories, technological centers and polymer companies began to actively participate and produce relatively important returns. It can be said that, thanks to the emergence of many research groups, polymer science at the national level covers practically the entire spectrum of polymer science and technology. Since the 1990's, polymer research has been focused on the development of polymers with specific technological properties. In fact, many laboratories are directly involved in the development of polymers for applications through EU and industrial collaborative projects and obtain important returns. For instance, Spain was the second country in the ranking of the NMBP Program of the EU, with 14.4% of the budget [3].
As a consequence, in most of the polymer groups, with a few exceptions, fundamental aspects of polymer science are decreasing in favor of polymer applications. It is important to note that, besides academic groups, there are several specific polymer technological centers connected to industry located throughout Spain.

Polymers in Spain Today
Most of the research lines related to polymer science and technology are covered by a large number of groups belonging to research institutions and universities, which are distributed throughout Spain. Polymer groups mainly constituted of chemists, engineers, physics and an increasing number of biologists, pharmacists, etc. Nowadays, most of the consolidated polymer research lines deal with (i) polymer synthesis: controlled polymerization, polycondensation; polymer functionalization, modelling, polymerization, process engineering, etc.; (ii) polymer physics: polymer structure, polymer dynamics, crystallization, gelation, rheology, etc., (iii) polymers for applications encompass: biomaterials, food packaging, polymer membranes, transport, sensors, etc. or more recently polymers for a circular economy. Compared to a few years ago, the research lines undertaken by different polymer research groups are continuously evolving, probably mediated by the research projects in which they are involved for which they receive funding. Moreover, there are research lines that are only specific to one or two groups, whereas others are common to many research groups, with the risk of sometimes overlapping one another (as happens all over the world). We can say that Spanish polymer research lines are among the challenges proposed by Macromolecules [4] and Progress in Polymer Science [5], even if the number of challenges proposed by Macromolecules in the opinion of this author is insufficient.
This Special Issue "State-of-the-Art on Polymer Science and Technology in Spain represents a detailed overview of recent research developments on fundamental and applicationinspired aspects of polymer science in Spain addressed by different polymer research groups. As a whole, it contains 42 contributions, of which 9 are reviews and 33 are articles/communications (including this short overview). Even though this monograph set is not unified by a common approach to identify the most outstanding challenges on polymer science, it is of great help to gathering of all the knowledge behind these works that contribute to the development of novel polymer materials and to understand the most relevant aspects of polymer behavior.
To summarize the content of the Issue, first, it is worth considering the nine reviews, ordered chronologically in term of time of reception. They cover different topics: fundamentals of polymer structure and physics; polymer rheology in Spain over the last 25 years; polyelectrolyte and natural polymer multilayers; polymer self-assembly; conjugated polymers; collagen based-biomaterials and chitosan based-biomaterials; and polymer crystallization. In the following, a short description of each review is given starting with the most general reviews, grouped thematically: 1 It also provides information related to the first steps in the field of rheology in Spain, the pioneers and the Spanish rheology group (GER, created in 1983). The manuscript is divided into six sections, corresponding to different families of industrial polymers: thermoplastics, thermosets, adhesives, biopolymers, composites and nanocomposites, and polymer-modified bitumen. Moreover, the rheological behavior of these materials in processing methods such as extrusion, injection molding, additive manufacturing, and others is discussed, based on the literature results. A detailed qualitative and quantitative view of the most outstanding achievements, based on the rheological criteria of the authors, is also offered.
Other contributions related to rheology of polymer gels, a subject of initial collaboration between POLYMAT (UPV/EHU) and ICTP-CSIC (Antxon Santamaria and Carmen Mijangos) are not included in this section [8,9], probably because they will be reported in the Special Issue of Polymers, entitled Rheology Applied to Polymer Characterization and Processing. A Themed Honorary Issue to Prof. Antxon Santamaria [10].
3 and 4. Two reviews focused on the layer by layer methodology (R5 [11] and R6 [12]). Polyelectrolyte Multilayers on Soft Colloidal Nanosurfaces: A New Life for the Layer- . Both reviews are complementary. The first discusses some fundamental aspects related to deposition methodologies commonly used for fabricating LbL materials on colloidal templates together with the most fundamental physicochemical aspects involved in the assembly of LbL materials. Furthermore, it proposes an analysis of some of the current trends on the fabrication of LbL materials using soft colloidal nanosurfaces, including liposomes, among others. The second review collects the main advances concerning multilayer assembly of natural polymers employing the most used LbL techniques, i.e., dipping, spray and spin coating, leading to multilayer polymer structures and the influence of several variables, i.e., pH, molar mass, and method of preparation, in this LbL assembly process. Finally, the review reports the employment of these multilayer biopolymer films in selected biomedical applications (i.e., platforms for tissue engineering, drug delivery or thermal therapies). . This article is focused on the synthesis, structure, crystallization behavior and mechanical properties of isodimorphic random biodegradable copolyesters based on poly (butylensuccinate) and poly (caprolactone). It also provides a comprehensive analysis of the main recent results on PBS-ran-PCL random copolyesters with different molecular weights. This work also shows that the comonomer composition and crystallization conditions are the major factors responsible for the crystalline morphology, crystallization kinetics and mechanical performance of isodimorphic random copolyesters. In this work, the relationships between the comonomer composition and mechanical properties are also addressed 9. (R9 [16]).
Secondly, the themes of the other 32 articles of this Issue reporting the recent advances in several fields of polymer science and technology (this overview not included) are briefly outlined in Table 1. Since contributions are chronologically placed, under author criteria, articles are compiled in four general research topics. (i) Polymer Synthesis/Fabrication: synthesis/preparation of new monomers, polymers and composites, with 16 contributions; (ii) Polymers for applications: biopolymers, sustainable polymers and bio-applications, with eight contributions; (iii) Specific preparative routes, with five contributions and (iv) Fundamental aspects of polymers science, with two contributions. In order not to enlarge the table, only a few representative words have been selected from the title or abstracts. The table includes the name of the first author and the name of corresponding or representative author (reviews are not included). Table 1. List of 32 articles, collected by the name of the first author, the name of the corresponding author (and other representative authors) and some representative words.

María Blanco María Blanco
Collagens from European hake and Blue shark skin: differences in the subunit composition influencing the crosslinking pattern. [35] Angela Varela-Garcia Carmen Alvarez-Lorenzo Design of hydrogel contact lenses endowed with an affinity for acyclovir and its prodrug valacyclovir [36] Jone

A. García-Collado A. García-Collado
Application of the finite element method to the incremental formation of polymer sheets: the thermomechanical coupled model [48] Marta Romay Nazely Diban Thermodynamic modeling and validation of the temperature influence in ternary phase polymer systems [49] As a whole, this monograph collects the contributions of nearly 200 different authors that belong to 24 different national Institutions (>30 different centers/departments) from Universities and CSIC distributed throughout the whole of Spain. It is important to remark than two-thirds of the contributions arise from collaborations between two or more Institutions, half of which involve European research groups and the other half involving international collaborations with research groups outside the EU, or from China, Australia or the USA.
Even though many of the consolidated research groups in Polymer Science in Spain have contributed to this Special Issue, it only gives partial information of all the polymer themes that are currently being investigated by Spanish teams and, therefore, it does not represent the broad polymer knowledge acquired along many years of research in Spain. In fact, some of the manuscripts published by well consolidated polymer groups report on very specific parts of their research and not the whole activity of the group. In addition, there are many contributions from research groups that are not exclusively working on polymers or have not been working in the field for a long period of time, but are producing outstanding results in the wide spectrum of polymer science Nevertheless, the considerable effort made by the sum of individual teams has contributed to promotion of polymers R+D in Spain to a European competitive level. It is important to note that, nowadays, polymer research groups in Spain are distributed all around the autonomous/local communities, see Figure 1. For more detailed information, see [1]. Most polymer researchers are also involved in the training and formation of PhD, MSc and BSc students and experts (every year,~50 students receive their PhD in polymer science in Spain), which constitutes highly specialized personnel with a lot of demand from private companies and research institutions all over the world. It is worth mentioning some specific courses and two official Master's Degrees specific to polymer science that are currently being taught in POLYMAT and ICTP-CSIC, those being the High Specialization Master's degree in Plastics and Rubber (ICTP-CSIC) the first specialized course on Polymer Science in Spain (starting in 1959).
It is important to add that, although this overview is focused on the R+D polymer research from universities and scientific institutions, polymer science and technology in Spain has a network of specific Polymer Technology Centers (or centers which are mostly dedicated to them) attached to different communities and distributed throughout the geography (i.e., AIMPLAST; AIITIP; CIDAUT, CIDETEC, GAIKER and others).
Related to technology of polymers in Spain, it is worth showing some figures. The plastics production and transformation industry in our country accounts for almost 50% of the chemical industry. There are 2200 plastics transformation companies with more than 100,000 workers and 350 plastic raw material manufacturer companies with 11,000 workers [50]. This large production of polymers in Spain is due, on the one hand, to the establishment of many of the large multinational companies within the country and, on the other hand, to the fact that Spain is the first/second largest automobile manufacturer in Europe, an industry that is a large polymer consumer.

Polymers in Spain within the European, Latin American and International Communities
Within this general polymer science framework, it is worth highlighting the creation of scientific associations related to Polymers in Spain (similar to the ones existing in other countries) and the active participation of Spanish laboratories in the association activities. El Grupo Especializado de Polímeros-The specialized group of polymers (GEP), see the webpage in [51], emerged in 1986 within the Spanish Royal Society of Chemistry (RSEQ) and Spanish Royal Society of Physics (RSEF). Since then, it has promoted the collaboration between different polymer research groups through the organization of different events. As a result of the active participation of a large number of members in various activities and a governing board dedicated to maintaining very active initiatives around the specialized group of polymers, GEP is the second largest group in terms of number of members and one of the most active groups in the RSEQ.
Every two years, chaired by a Spanish polymer team, GEP organizes four-day meetings for all the scientists of the polymer community with the participation of industrial partners in different towns of the country. The GEP meetings have been held uninterruptedly since 1989, except for the case of GEP-SLAP2020 that had to be postponed to 2022 due to COVID-19. The next meeting, GEP-SLAP 2022 (see webpage in [52]), refers to the joint Spanish-Latin Americano meeting, i.e., the XVI Conference of the Grupo Especializado de Polímeros (GEP2022) and the XVII Simposio Latinoamericano de Polímeros (SLAP 2022) GEP also promotes the meetings of young polymer researchers (JIP), beginning in 2002 with the 1st National Congress of young researchers in La Manga (Murcia) and, since then, on a biennial basis. It is worth highlighting the joint Spanish (JIP) and French (JEPO) young polymer research congress in 2015, the JIP/JEPO 2015 Conference, in San Sebastián. It also maintains an important recognition for the best theses produced annually by young members of the GEP. GEP community also joints the biennial Symposium Latinoamericano de Polímeros (SLAP).
GEP participation in international actions organized in the framework of the European Polymer Federation, EPF, in which actively collaborates in the organization of European Polymer Congress, every two years, as well as in the specialized schools that are organized is noteworthy. For instance, in 2011, Granada University and ICTP-CSIC hosted the 13th EPF Congress, bringing together more than 1300 european and worldwide polymer researchers.
Spain has also promoted the associations of the Plastics industry: the Spanish Plastics Center ( Within this general context of polymer research in Spain, the continuous growth of polymer groups has aided to the Spanish research reach a place between the first European countries, at least in terms of publications. Spain is placed in the fourth position after Germany, the United Kingdom and France. From 1996 to 2020 Spain has published 12,024 documents. These figures are collected from the SCIMAGO Journal and country rank database [53], searching by the following categories: Material Science; Polymers and Plastics; Western Europe; 1996-2020. There are no data prior to 1996. It is worth noting that, in our country, every 10 years, the number of publications on polymers has doubled and there has been a constant increase in the quality of publications.

Conclusions
In Spain, polymer research is growing and polymer groups are extending throughout the whole geography. There are two important and specific research polymer centers and many consolidated and strong groups in practically all public and some private universities. Besides polymer research groups there are several technological centers, large polymer manufacturing companies and many small/medim manufacturing and processing companies Based on established (taking into account) scientific and economical rankings, the polymer scientific level is equal to or higher than the economical level of the country in the EU ranking.