Aminopyridinato Complexes as Possible Alternatives for Metallocenes in Ethylene Polymerization

Polyethylene is the most widely used synthetic polymer in the world. Most polyethylene is made with Ziegler-Natta catalysts. Polyethylenes for special applications are made with metallocenes, which are nowadays heavily patented. It is laborious therefore, to develop new metallocenes. The aim of this work was to investigate the feasibility of replacing the cyclopentadienyl ligands of metallocenes by aminopyridinato ligands without losing the good properties of the metallocenes, such as high activity and formation of linear polymer. The subject was approached by studying what kind of catalysts the metallocenes are and how they catalyze polyethylene. The polymerization behavior of metallocenes was examined by synthesizing a piperazino substituted indenyl zirconocene catalyst and comparing its polymerization data with that of the indenyl zirconocene catalyst. On the basis of their isolobality, it was thought that aminopyridinato ligands might replace cyclopentadienyl ligands. It was presumed that the polymerization mechanism and the active center in ethylene polymerization would be similar for aminopyridinato and metallocene catalysts. Titanium aminopyridinato complexes were prepared and their structures determined to clarify the relationship between structure of the catalyst precursor and polymerization results. The ethylene polymerization results for titanium 2-phenylaminopyridinato catalysts and titanocene catalysts were compared.

Radiation effects in supported nanoparticles

Nanotechnology applications are entering the market in increasing numbers, nanoparticles being among the main classes of materials used. Particles can be used, e.g., for catalysing chemical reactions, such as is done in car exhaust catalysts today. They can also modify the optical and electronic properties of materials or be used as building blocks for thin film coatings on a variety of surfaces. To develop materials for specific applications, an intricate control of the particle properties, structure, size and shape is required. All these depend on a multitude of factors from methods of synthesis and deposition to post-processing. This thesis addresses the control of nanoparticle structure by low-energy cluster beam deposition and post-synthesis ion irradiation. Cluster deposition in high vacuum offers a method for obtaining precisely controlled cluster-assembled materials with minimal contamination. Due to the clusters small size, however, the cluster-surface interaction may drastically change the cluster properties on deposition. In this thesis, the deposition process of metal and alloy clusters on metallic surfaces is modelled using molecular dynamics simulations, and the mechanisms influencing cluster structure are identified. Two mechanisms, mechanical melting upon deposition and thermally activated dislocation motion, are shown to determine whether a deposited cluster will align epitaxially with its support. The semiconductor industry has used ion irradiation as a tool to modify material properties for decades. Irradiation can be used for doping, patterning surfaces, and inducing chemical ordering in alloys, just to give a few examples. The irradiation response of nanoparticles has, however, remained an almost uncharted territory. Although irradiation effects in nanoparticles embedded inside solid matrices have been studied, almost no work has been done on supported particles. In this thesis, the response of supported nanoparticles is studied systematically for heavy and light ion irradiation. The processes leading to damage production are identified and models are developed for both types of irradiation. In recent experiments, helium irradiation has been shown to induce a phase transformation from multiply twinned to single-crystalline nanoparticles in bimetallic alloys, but the nature of the transition has remained unknown. The alloys for which the effect has been observed are CuAu and FePt. It is shown in this thesis that transient amorphization leads to the observed transition and that while CuAu and FePt do not amorphize upon irradiation in bulk or as thin films, they readily do so as nanoparticles. This is the first time such an effect is demonstrated with supported particles, not embedded in a matrix where mixing is always an issue. An understanding of the above physical processes is essential, if nanoparticles are to be used in applications in an optimal way. This thesis clarifies the mechanisms which control particle morphology, and paves way for the synthesis of nanostructured materials tailored for specific applications.

Communicative and Anticipatory Decision-making Supported by Bayesian Networks

The purpose of this research is to draw up a clear construction of an anticipatory communicative decision-making process and a successful implementation of a Bayesian application that can be used as an anticipatory communicative decision-making support system. This study is a decision-oriented and constructive research project, and it includes examples of simulated situations. As a basis for further methodological discussion about different approaches to management research, in this research, a decision-oriented approach is used, which is based on mathematics and logic, and it is intended to develop problem solving methods. The approach is theoretical and characteristic of normative management science research. Also, the approach of this study is constructive. An essential part of the constructive approach is to tie the problem to its solution with theoretical knowledge. Firstly, the basic definitions and behaviours of an anticipatory management and managerial communication are provided. These descriptions include discussions of the research environment and formed management processes. These issues define and explain the background to further research. Secondly, it is processed to managerial communication and anticipatory decision-making based on preparation, problem solution, and solution search, which are also related to risk management analysis. After that, a solution to the decision-making support application is formed, using four different Bayesian methods, as follows: the Bayesian network, the influence diagram, the qualitative probabilistic network, and the time critical dynamic network. The purpose of the discussion is not to discuss different theories but to explain the theories which are being implemented. Finally, an application of Bayesian networks to the research problem is presented. The usefulness of the prepared model in examining a problem and the represented results of research is shown. The theoretical contribution includes definitions and a model of anticipatory decision-making. The main theoretical contribution of this study has been to develop a process for anticipatory decision-making that includes management with communication, problem-solving, and the improvement of knowledge. The practical contribution includes a Bayesian Decision Support Model, which is based on Bayesian influenced diagrams. The main contributions of this research are two developed processes, one for anticipatory decision-making, and the other to produce a model of a Bayesian network for anticipatory decision-making. In summary, this research contributes to decision-making support by being one of the few publicly available academic descriptions of the anticipatory decision support system, by representing a Bayesian model that is grounded on firm theoretical discussion, by publishing algorithms suitable for decision-making support, and by defining the idea of anticipatory decision-making for a parallel version. Finally, according to the results of research, an analysis of anticipatory management for planned decision-making is presented, which is based on observation of environment, analysis of weak signals, and alternatives to creative problem solving and communication.

Metsänomistajille tarjottavat palvelut, palveluntarjoajat ja palvelukentän rakenne

Suomessa metsänomistajille on tarjolla neljäntyyppisiä eri palveluita metsänhoidossa, puukaupassa, omaisuudenhoidossa ja informaatiopalveluissa. Palveluita tarjoaa joukko hyvin erikokoisia organisaatioita, joista osa toimii markkinalähtöisesti toisten tarjotessa palveluitaan lakiperusteisesti. Metsäalan palvelumarkkinat ovat nyt murrosvaiheessa, ja muutoksia on tapahtumassa sekä tarjonta- että kysyntäkentässä. Metsänomistajille tarjottavien palveluiden markkinoita ei tarjoajanäkökulmasta ole aiemmin tutkittu kattavasti. Tutkimukset ovat usein keskittyneet suppeasti johonkin palvelulajiin, eikä kokonaiskuvausta palvelumarkkinoista omaisuudenhoitopalvelut mukaan lukien ole ollut tarjolla. Tarjoajakenttään on odotettavissa muutoksia, sillä metsäalan palvelumarkkinoiden rahoituspohjaa ollaan muuttamassa, jolloin markkinoiden kilpailu vapautuu nykytilanteeseen verrattuna. Muutokset koskevat etenkin lakisääteisten organisaatioiden toimintaa, mutta ne tulevat vaikuttamaan koko toimialaan. Kysyntäkentässä aiempi tutkimus on ollut kattavampaa. Etenkin metsänomistajarakenteen muutosta, joka johtuu pääasiassa metsätilojen siirtymisestä kaupungistuneelle sukupolvelle, on tutkittu runsaasti. Lisäksi palveluiden kysyntään vaikuttavia tekijöitä ja palvelun eri laatu-ulottuvuuksia on tutkittu. Voidaan kuitenkin epäillä, kyetäänkö markkinoilla tarjoamaan sellaisia palveluita, jotka todella kattavasti tyydyttävät metsänomistajien tarpeita ja pystyvät tarjoamaan sellaisia hyötyjä, joista ollaan valmiita maksamaan. Tässä tutkimuksessa on tarkasteltu nykyisiä metsäpalvelumarkkinoita, sillä kokonaiskuvan luominen nykytilanteesta tarjoaa pohjan tulevien muutoksien ennakoimiselle. Tutkimusmenetelmänä on käytetty kvalitatiivista sisällönanalyysiä, ja tarkastelun kohteena on ollut palveluntarjoajien metsänomistajille suuntaama markkinointimateriaali – pääasiassa tarjoajien internetissä oleva materiaali. Markkinointimateriaalien tukena on käytetty palveluorganisaatioiden edustajien ja alan asiantuntijoiden teemahaastatteluita. Palveluita ja organisaatioita on tarkasteltu niiden asiakkaan kokemien hyötyjen pohjalta, joita markkinoinnissa palveluihin ja palveluntarjoajiin on pyritty liittämään. Teoreettisesti taustalla on käytetty mallia kuluttajan valintakriteereistä hankintapäätöstä tehtäessä. Tulosten perusteella on löydettävissä kysynnän kannalta kriittisiä palveluita, joiden ympärille palvelukokonaisuuksia on rakennettu. Metsänomistamisen odotetaan olevan kannattavaa, joten eräs palveluntarjonnan haasteista syntyy alan tarpeesta rahoittaa itsensä mielekkäällä aikajänteellä. Tämä luo tarpeen tuloja synnyttävien palveluiden yhdistämiseen kokonaisuuksiksi kustannuksia aiheuttavien, mutta muita hyötyjä tuottavien palveluiden kanssa. Tarjoajien kannalta tärkeää on kyetä luomaan asiakkaita hyödyttäviä palvelukokonaisuuksia muuttuville markkinoille.

Tuning the interfacial properties of supported metal nanoclusters

Nanoclusters are objects made up of several to thousands of atoms and form a transitional state of matter between single atoms and bulk materials. Due to their large surface-to-volume ratio, nanoclusters exhibit exciting and yet poorly studied size dependent properties. When deposited directly on bare metal surfaces, the interaction of the cluster with the substrate leads to alteration of the cluster properties, making it less or even non-functional. Surfaces modified with self-assembled monolayers (SAMs) were shown to form an interesting alternative platform, because of the possibility to control wettability by decreasing the surface reactivity and to add functionalities to pre-formed nanoclusters. In this thesis, the underlying size effects and the influence of the nanocluster environment are investigated. The emphasis is on the structural and magnetic properties of nanoclusters and their interaction with thiol SAMs. We report, for the first time, a ferromagnetic-like spin-glass behaviour of uncapped nanosized Au islands tens of nanometres in size. The flattening kinetics of the nanocluster deposition on thiol SAMs are shown to be mediated mainly by the thiol terminal group, as well as the deposition energy and the particle size distribution. On the other hand, a new mechanism for the penetration of the deposited nanoclusters through the monolayers is presented, which is fundamentally different from those reported for atom deposition on alkanethiols. The impinging cluster is shown to compress the thiol layer against the Au surface and subsequently intercalate at the thiol-Au interface. The compressed thiols try then to straighten and push the cluster away from the surface. Depending on the cluster size, this restoring force may or may not enable a covalent cluster-surface bond formation, giving rise to various cluster-surface binding patterns. Compression and straightening of the thiol molecules pinpoint the elastic nature of the SAMs, which has been investigated in this thesis using nanoindentation. The nanoindenation method has been applied to SAMs of varied tail groups, giving insight into the mechanical properties of thiol modified metal surfaces.