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Giulio Natta,
l’uomo, lo scienziato

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Biographical notes. University career

Giulio Natta was born in Porto Maurizio (Imperia) on 26 February 1903, to Ligurian parents: Francesco Maria, an eminent judge, and Elena Crespi. After gaining a diploma from Colombo High School in Genoa he was admitted to Genoa University, aged only 16 years, to study on the two-year propedeutic mathematics course. In 1921 he enrolled on practical courses in Industrial Engineering (Chemistry) at the Polytechnic of Milan, graduating in 1924 at the age of 21 with a degree in Industrial Engineering (Chemistry), having also studied from 1922 at the Institute of General Chemistry under the Directorship of Professor Giuseppe Bruni, whose assistant Natta immediately became.
Giulio Natta lost no time in embarking on a university career with Giuseppe Bruni and, after three years, was appointed to the teaching staff in General Chemistry as "libero docente".
In 1925 he was appointed to teach Analytical Chemistry, a post which he held until 1932. Meanwhile, from 1929 to 1933, he also taught a course in Physical Chemistry at the Faculty of Science of the Univer-sity of Milan.
In 1933 he was awarded the chair of General Chemistry at the University of Pavia, where he remained until 1935, and where he also taught Physical Chemistry. In 1935 he was invited to take up the prestigious professorship in Physical Chemistry at the University of Rome and, in 1937, the chair in Industrial Chemistry at the Polytechnic of Turin. In that period Mario Giacomo Levi was forced, due to racial persecution, to leave the Directorship of the Institute of Industrial Chemistry of the Polytechnic of Milan and in 1938 Natta was appointed in his place. Natta was to remain at the Polytechnic of Milan until 1973 as Full Professor of Industrial Chemistry and Director of the Institute of the same name.

The scientist

An examination of Natta's academic curriculum and of his scientific works reveals that he did not have a proper teacher as such, but that he was self-taught.
His passion for chemistry innate. While still a student, he had set up and equipped a laboratory in his home in Via Rugabella in Milan, where he would conduct experiments, sometimes with hazardous consequences.
In the early 1920s, while doing his military service, he conducted experiments at the Polytechnic of Milan on mustard gas, a vesicant gas used in the First World War: he tested the characteristics of his preparations on the skin of his own wrist, for years marked by small scars. To be nearer to his research he set up a camp bed in a laboratory at the Institute of General Chemistry.
His first scientific work was published in the "Gazzetta Chimica Italiana" 1923 (vol. 53, p. 532). But his scientific activity ranged across various sectors, as we describe later (see pdf document).

Studies in structural chemistry

Natta's research soon became oriented towards structural chemistry, first by studying the application of X-rays and then by tackling a subject that was ultra-modern at that time: the diffraction of electron beams. These were techniques that in Italy were being applied for the first time - and in the centre which could then be considered the most important in Italy for such studies - to the resolution of problems in the field of chemistry.
In the study of compounds of metallic oxides and sulphides he identified the relationship between the ionic radii of the components which affect the formation of particular structures. He went deeply into the study of the phenomena of isomorphism and accomplished the preparation of solid solutions with new methods, such as by precipitation. He defined the structure of several hydroxides and hydrates containing coordination water. With a special and ingenious spectrograph for low temperatures, which he constructed himself, he described the structure of gases that solidify at low temperatures. In the case of halogenidric acids which present the same structure as noble gases having the same number of electrons, he arrived at a direct method for the determination of the ionic radii in crystals. He determined the structure of solid hydrogen sulphide and other compounds of hydrogen.
It was these researches that aroused in Natta an interest also in the issue of applications. His first industrial patent dates back to 1927.

The chemistry of carbon monoxide, alcohols and formaldehyde (C1 chemistry)

The first scientific works on the synthesis of methanol and higher alcohols (preceded and accompanied by several patents, extended abroad) date from 1930. At that time methanol was one of the most important industrial organic derivative products, used for the preparation of various organic compounds and as a solvent, and its synthesis was the object of research at foreign companies and in the most adavanced countries.
On the scientific front, Natta's work in this sector made it possible, in particular, to relate catalytic activity to the dimensions of individual crystals, to define reaction mechanisms, to highlight the role of a number of promoters and to propose some new catalysts.
On the applicative front, his work led to the construction in 1930 of the first Italian methanol plant in Coghinas (Sassari), followed by others, in Italy, Switzerland and South America, with a capacity, notable for that time, of over 10,000 t per year.
His work in this sector brought Natta international fame, with the result that he was subsequently asked to write two chapters for a renowned series of volumes: "Catalysis", edited by P.H. Emmett [Synthesis of Methanol, in "Catalysis", P.H. Emmett (editor), Reinhold Corp., New York 1955; Direct Catalytic Synthesis of Higher Alcohols from Carbon Monoxide and Hydrogen, ivi, 1957].
The 1930s also saw his studies on gasification with oxygen at low temperatures of domestic fuels, carried out with an experimental gas generator which he installed at the Institute of Industrial Chemistry at the Polytechnic of Milan. These researches, too, led to the construction of a number of industrial gas generators, each one with a potential of 50,000 m3 of gas per day, used (during periods of economic self-sufficiency) for the preparation of ammonia, nitrogen fertilizers, fuels and methanol.
Still in the early 1930s, Natta took up the study of the preparation of formaldehyde (another important organic derivative, used in the preparation of thermosetting resins -phenol/formaldehyde resins (Bakelite), urea/formaldehyde resins, adhesives, paints, explosives) by means of oxidative dehydrogenation of methanol which, later on, was to lead to the production of new catalysts applied on an industrial scale.

First researches into high polymers

The first work by Natta in the field of high polymers dates from 1934, following a period spent in Germany, in Freiburg (with a study grant awarded by the Volta Foundation in 1932) at the Laboratory of Dr. Seeman, where Natta met Prof. Hermann Staudinger, Nobel Laureate in Chemistry in 1953 for his research into the properties and structure of high polymers, both natural (cellulose, natural rubber, gutta-percha) and synthetic.
Staudinger had already demonstrated in 1922 that these substances were made up of large molecules rather than aggregates, coining the term "macromolecules". It was to substances of this kind, some of which he received from Staudinger, that Natta applied for the first time the technique of electron diffraction in order to characterize their structure.

Hydrogenation of furfural and carbohydrates

For some years more, however, he was to be concerned with other problems of an applicative nature: the hydrogenation of carbohydrates for the production of glycols and glycerol, which was important for national self-sufficiency, the hydrogenation of furfural, the synthesis of isooctane (as fuel), and the production of hydrogen from methane.

Research into synthetic rubber

In 1938, under commission from the government and in close collaboration with industry, Natta devoted himself to research into the production of synthetic rubber in Italy, working mainly on the separation - from l-butene - of butadiene in a sufficiently pure state to permit its use for the production of elastomers by means of copolymerization with styrene (Buna S). This was an extraordinarily difficult operation to conduct physically, owing to the extreme closeness of the boiling points of the two compounds. Natta brought about a new physical method of separation, which he himself meticulously studied and perfected: fractionated absorption.


In the immediate post-war period Natta tackled a new subject of great topical interest at that time: "oxo-synthesis", a synthesis discovered in Germany, which made it possible to obtain aldehydes (and alcohols) by means of catalytic addition of CO and H2 to olefins. Natta's contributions in this sector made it possible to clarify reaction mechanisms and better define operating conditions, and they were then applied in the construction of the first oxo-synthesis plants in Ferrara, within the first major petrochemicals complex in Italy.

Stereospecific polymerization

However, the work for which Natta is most famous and which led to his being awarded the Nobel prize, together with Karl Ziegler of the Max Planck Institute in Mülheim, concerns stereospecific polymerization, which he discovered - thanks partly to a series of lucky circumstances - and studied exhaustively.
In 1952, while attending a conference given by Karl Ziegler in Frankfurt, he was struck by the fact that ethylene polyaddition took place in the presence of organometallic compounds, producing oligomers of low molecular weight, but perfectly linear; and that, in the dimerization of the ?-olefin, a single dimer was produced, but with a clearly defined structure, unlike the complex mixes produced by normal cationic catalysts. Natta invited Ziegler to hold a conference at the Polytechnic of Milan and suggested that Montecatini should draw up a contract with Ziegler to grant the company the use of any results, past and future, obtained by Ziegler in the field of organometallic compounds and their application.
In the meantime, Natta set up at the Polytechnic an advanced course in organic aliphatic industrial chemistry for trainee graduates, employed by Montecatini but selected by Natta, who was thus able to have at his disposal in his laboratories an exclusive group of skilled researchers, with whom he began the study of ethylene polyaddition and the polymerization of other olefins with organometallic compounds.
In 1953 Ziegler filed his first patent on the polymerization of ethylene to high polymers, obtained at low pressure in the presence of catalysts consisting of metallo-alkyls of metals from the 1st and 3rd groups of the periodic system and compounds of transition metals from the 4th to the 8th group. These studies by Ziegler, though of great importance, were limited to ethylene polymerization, which was already being obtained at that period in great steam cracking plants, together with substantial quantities of propylene - which at the time had limited uses - into which Natta directed his own research.
In the first months of 1954, using Ziegler's catalysts, Natta obtained the first partly crystalline polypropylene and on 11 March noted in his diary, "Made polypropylene". He at once recognized that the crystallinity of the polymer thus obtained was due to a particular type of steric regularity, which he defined as "isotactic".
Before Natta's discovery, the succession of the monomeric units along the polymeric chains in synthetic polymers derived from vinyl-type monomers had been disordered, particularly from the steric point of view. Stereospecifìc polymerization made it possible for the first time to synthesize polymers that were ordered, both chemically and sterically, starting from vinylic or in any case unsaturated monomers.
Prior to this, polymers of this type had only been found in nature (for example natural rubber and gutta-percha).
The type of regularity involved in the concatenation of the monomeric units in the macromolecules of polymeric products is a determining factor governing the properties of the polymer itself. On this subject, it is worth recalling the differences between natural rubber and gutta-percha (both are isoprene polymers: the former is a 1,4-cis polyisoprene and the latter a 1,4-trans polyisoprene). Moreover, the significant differences in mechanical, physical and organoleptic properties observable between cellulose and starch are due to the difference in the types of steric regularity with which monomeric units that are identical (glucose) succeed one another along polymeric chains.
The stereoregular polypropylene defined by Natta as "isotactic" is a crystalline powder with a density lower than that of water and a melting point of 170° C, from which products with a tensile stress of 3-4 kg/mm2 can be made; whereas non-stereoregular polypropylene (atactic) is an oily substance.
The first work on this discovery was presented at the National Lyncean Academy in 1955 [G. Natta, A new class of polymers of alpha-olefin having exceptional regularity of structure, in "Atti Acc. Naz. Lincei", Mem. 4 (8), 61 (1955)].
It is impossible to outline in just a few pages the breadth and importance of the contributions made by Natta and his School in this field; we provide here a simple list of the subjects that the Institute of Industrial Chemistry of the Polytechnic of Milan tackled in the period from 1953 to 1971 (in the following years, up to 1979, the publications bearing Natta's name were collections, essays and educational texts), and which were developed in very nearly one thousand scientific publications (see also Appendix A, where the subjects are subdivided according to topics and periods, with the indication of the main collaborators):

- synthesis, characterization of the structure in the crystalline state and determination of a number of physicochemical, mechanical and physical properties of several new types of polymers;
- preparation, study and characterization of catalytic systems formed from a transition element compound and an organometallic compound (Ziegler-Natta catalysts) or from organometallic compounds alone;
- studies on the mechanisms and kinetics of various polymerizations;
- synthesis of polytactic polymers;
- asymmetric syntheses;
- synthesis of polyolefin copolymers with statistical distribution and their application for the preparation of saturated elastomers;
- synthesis of alternating crystalline copolymers;
- preparation and characterization of saturated and unsaturated elastomers and fibres;
- grafted polymers;
- stereoregular polymers obtained from inclusion compounds;
- use of polymers in the field of pharmacology;
- application of spectroscopic (IR, NMR, ESR, Raman), radiochemical and various analytical techniques to the study of polymers, monomers, catalytic systems and their components and various complexes.

The importance of these researches on a more strictly scientific level is not limited to the fact that stereospecific polymerization permitted for the first time the synthesis of stereoregular polymers obtained from monomers of various kinds. Just as fundamental was the work on the discovery of various catalytic systems and on their behaviour, and the work on the determination of the structure of polymeric substances, on the relationship between properties and structure, and on asymmetrical syntheses: indeed, with this type of synthesis a link was established between a class of phenomena occurring in nature and reactions achievable for the first time in the laboratory. In the Presentation Speech made by Professor A. Fredga, Member of the Nobel Committee for Chemistry at the Royal Swedish Academy of Sciences, on the occasion of the awarding of the Nobel Prize we read: "Nature synthesizes many stereoregular polymers, for example cellulose and rubber. This ability has so far been thought to be a monopoly of Nature, operating with biocatalysts known as enzymes. But now Professor Natta has broken this monopoly".
Paul Flory, one of the greatest scientists in the field of polymers, himself awarded the Nobel Prize in Chemistry in 1974, in 1955 described Natta's discovery as "a revolution in the field of macromolecular chemistry".
This "revolution" subsequently affected the entire scientific and industrial world in this specialist sector, so that very soon after 1954-1955 most university and industry research laboratories involved in macromolecular chemistry in various parts of the world ended up focusing, to a greater or lesser extent, on activities concerned with the new technique of stereospecific polymerization. And for several years these laboratories were essentially inspired by the work of Natta and his School, which meant that for the most part they were doing follow-up research. It would not be wide of the mark to state that most of the significant results achieved in the field of stereospecific polymerization, broadly speaking, for several years after 1954 continued to come out of Natta's laboratories.
In the June 1961 issue of the J. of Polymer Science, dedicated to Natta as "The Father of Stereoregular Polymers" we read:
"Seldom has a scientific contribution aroused such a profound fundamental interest and been followed by such a rapid technical development as the series of publications by Professor Giulio Natta and his co-workers on the stereospecific polymerization of olefins, which started to appear in the Italian journals several years ago and have continued ever since. Many prominent scientists in many large research laboratories have become interested in the new technique and have focused their interests and efforts on its promotion. Yet Professor Natta has succeeded in maintaining undisputed leadership in this field of polymer chemistry and continues to surprise his colleagues by new and unexpected discoveries along the general principles of stereoregulation."

The extent and significance of the new fields of research activity originating from Natta's work can also be seen from the fact that, even today, over 50 years on from his discovery, stereospecific polymerization continues to be the object of numerous intense studies, both scientific and applicative.
On the applicative front such researches have led to the discovery of new types of polymers of great industrial interest, such as isotactic polypropylene, used in the production of plastics, synthetic fibres and transparent sheets, ethylene-propylene copolymers and 1,4-cis polybutadiene, two important synthetic elastomers.
To highlight the importance in the area of applications of these discoveries we may quote what was published in the November 1963 issue of "La Chimica e l'Industria", in the editorial dedicated to Natta, following the awarding of the Nobel Prize: "... the field of industrial chemistry has been 'ploughed' so deeply that it is unlikely to hold the surprise of any discoveries as significant as this". Over 50 years after the discovery made by Giulio Natta, this statement has still not been invalidated.
The importance in commercial terms of isotactic polypropylene, elastomers based on ethylene and propylene and 1,4-cis polybutadiene is shown by the fact that polypropylene is ranked in third place, in terms of commercial value, among all chemical products produced on an industrial scale, outdoing styrene polymers, polyamides, and vinyl chloride polymers and copolymers, while 1,4-cis polybutadiene and copolymers based on ethylene and propylene occupy second and third positions respectively in the ranking of synthetic rubbers.

One might now ask oneself how it was possible to achieve such significant results in such a short time. The crucial factor must indubitably be sought in the personality of Giulio Natta, in his thorough preparation in various branches of chemistry and in his gifted intuitions. But intuition and scientific preparation are not sufficient to develop research in a completely new field and on various substances that had not existed before then, even taking into account the fact that this research was characterized by a broad interdisciplinary approach and that it required methodologies and investigative techniques of numerous kinds. First and foremost it required means and a "School".
In the matter of the provision of economic means and equipment, we must acknowledge the credit to the company known then as Montecatini, in the person of the CEO in that period, Piero Giustiniani. The collection of equipment made available for carrying out the research was of a remarkable standard: from various pieces of apparatus for spectroscopic, analytical and physicochemical analyses, to the apparatus in the Plastics testing Laboratory (set up in 1952 with financial contributions from various companies); this Laboratory, in addition to conducting tests on behalf of third parties, contributed to characterizing several of the new polymers, in particular polypropylene and ethylene-propylene rubbers.
The "School", which in 1954-1955 originally consisted of some fifteen researchers, both assistant lecturers and Montecatini graduates - for the most part very young - later expanded into the Polytechnic itself with other Montecatini researchers and to other universities and CNR (National Research Council) centres, eventually turning out scientists who today hold, or held in the past, prestigious posts in Italian and foreign universities, in the most important national chemicals companies and in CNR research Centres and Institutes, which emerged with the creation of the National Centre for Macromolecular Chemistry and with the National Institute for Macromolecular Chemistry.

Giulio Natta's scientific personality, intuitions and dedication to research

The determining factor which made the accomplishment of such notable results possible, especially in the field of stereospecific polymerization, in a relatively short period of time, is to be discovered in Natta's personality, in his exhaustive preparation in various branches of chemistry, in his brilliant intuitions and in his extremely clear and thorough knowledge of the frontiers reached by technology and by chemical science, taken in the broadest sense: unlike the majority of other Nobel Laureates he was not a specialist. For Natta chemical science was one complete whole, from the study of molecules in the laboratory to the industrial plant.

His intuitions can best be illustrated with a few stories. Shortly after the discovery of the stereospecific polymerization of propylene he remarked, during a conversation with his assistants, that it would be possible to obtain elastomers by disturbing the tendency of polyethylene to crystallize, by means of the introduction of some irregularities into its chain, which was achievable with the copolymerization of ethylene with propylene. A few days later, the first ethylene-propylene copolymer was made in the laboratory, and its elastomeric properties were confirmed.
On another occasion Natta wanted to "find" - for reasons of patent protection - a crystalline polypropylene that was different from isotactic polypropylene, in other words syndiotactic polypropylene, whose existence had only been conjectured. In this case also, after a few days, the new polymer was identified and separated and its crystalline structure defined. A few months later a catalyst was produced which was highly syndiospecific in the polymerization of propylene.
Other episodes highlight Natta's profound dedication to research. In 1957 he was invited to give the keynote address at the 16th International Congress of Pure and Applied Chemistry (IUPAC) in Paris. Unfortunately he fell ill (it was his first symptoms of Parkinson's disease) and he was confined to his bed for several weeks. The lecture was prepared in lengthy sessions at his bedside. Some years later he underwent his first brain surgery: the very day of the operation, immediately after the surgery had been completed, he telephoned his assistant from the hospital to find out the result of an experiment that he was particularly interested in. He was an indefatigable worker. He would work until late at night, even on public holidays or during vacations, often accompanied by one of his assistants, who would take turns at his desk in Via Mario Pagano in Milano or at the houses where he stayed during vacations, a habit which Natta kept up even after he was seriously afflicted by Parkinson's disease, from which he suffered for some 20 years.

Natta was not only a great scientist, he was a great teacher. In the years preceding his work on stereospecific polymerization he had already trained scholars who were subsequently called on to take up prestigious university professorships.
In addition to the Nobel prize, Natta received innumerable national and international awards.

The professor

As well as his scientific activity, we should remember Natta's work as a teacher. He had a profound love of school and of teaching, and considered such activities to be among the most important and worthy. He would prepare every one of his lessons with great care, though rather than lessons it was more often a question of conferences, in which he would communicate the wealth of his experiments, expounding on subjects which he had been able to investigate at first hand.
As long as his state of health allowed it he was determined to continue to examine each of his students personally. The generations of chemical engineering students who had the privilege of attending his course, or of preparing their graduation thesis with him, will never forget his commitment to the role of "Professor".
His colleagues always recognised his great merit in having succeeded in modernizing the teaching of industrial chemistry, modelling it along rational and deductive lines which differed radically from the traditional approach.

The man

As a person, Giulio Natta was shy and reserved, although as a student he threw himself readily into undergraduate life and took part in student events. He had sincere human relationships with everyone, even if this was masked by an apparent detachment that was clearly due to his shyness. He could inspire respect, without ever raising his voice: he gave no orders either to his assistants or to his students, but only advice and suggestions. However, he managed to coordinate with kindness and tenacity the activity of various groups of researchers, each with its own specialist expertise, accepting the diverse personalities of each one.
His family life and his relations with various Italian and foreign scientists were looked after by his wife Rosita Beati, whom he married in 1935, a Humanities graduate and a woman of enormous culture, great sensitivity and vivacity, whose affection was also invaluable to the Professor. Rosita died before him, in 1968, to the profound grief of her children Franca and Giuseppe and everyone who had known her.
Ever since he was a student, Natta loved the outdoor life, with excursions to the mountains and skiing trips, and always retained his love of nature, the quiet restfulness of fishing, and long walks in the woods hunting for mushrooms. He was a great connoisseur of minerals, mushrooms and plants: when he had to travel to a foreign country he would read up on the types of trees he would find there.
And it was in the tranquillity of one of his houses, on the hills of Bergamo, with his daughter Franca by his side, that on 2 May 1979 he passed away after years of physical suffering endured with great strength of spirit.

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