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The advancement of polymer science has given rise to the development of sequence-controlled polymers. Within this domain, sequence-defined polymers stand out as a remarkable subclass characterized by an unprecedented level of uniformity. These sequence-defined polymers exhibit precise positioning of each monomer, offering perfect control over their structural arrangement. While strategies using click chemistry and living polymerizations still face limitations of dispersity and positioning, the iterative synthesis approach proves to be the most suitable solution. The application of sequence definition in conjugated polymers holds great potential for advancing the field of polymer science. It offers the opportunity to synthesize novel materials with precisely controlled optoelectronic properties. However, limited research has been performed in this area thus far. Form initial investigations, it is evident that the AB+CD method, incorporating orthogonal reactions, represents the most efficient approach with minimal steps. Nevertheless, further exploration is needed for its applicability in sequence-defined conjugated polymers. In a previous study conducted in our group, a novel strategy was developed utilizing alternating Suzuki-Miyaura cross-coupling reactions and Horner-Wadsworth-Emmons reactions. This approach preserves conjugation, achieves high yields, and minimizes the formation of by-products. The aforementioned approach is employed to synthesize sequence-defined macromolecules, allowing for the investigation of the influence of chiral monomers. However, prior to conducting this investigation, it is necessary to synthesize the monomers that will serve as the building blocks. All monomers in this study are phenyl-based, with functional groups positioned at the 1 and 4 positions. One type contains a phosphonate and a bromide, while another consists of a boronate ester and an aldehyde. In total, 4 monomers are synthesized, including a chiral type with a (S)-2-methylbutyl sidechain and an achiral type with an octyl sidechain. Additionally, an achiral starting monomer with one active and one protected functional group is applied, featuring a bromide and a protected hydroxyl group. After the successful synthesis of the monomers, the oligomers are synthesized by employing the aforementioned strategy. Two distinct sequences are synthesized, wherein the position of the chiral monomers serves as the differentiating factor. This allows for the investigation of the influence of chiral monomer position. The oligomers are gradually expanded until they reach the size of hexamers, ensuring an adequate level of variability in the positioning of the chiral monomer. The characterization of both sequences, spanning from dimers to hexamers, is carried out extensively using various measurement techniques. The purity and structure of the oligomers are confirmed using 1H-NMR and 13C-NMR spectroscopy. The smaller chains are also characterized via mass spectroscopy. The determination of the number average molar mass and dispersity is achieved through GPC, which confirms the desired growth of the oligomers and their monodisperse nature. UV-VIS spectroscopy is employed to validate the preservation of the conjugated backbone by observing a red shift as the sequence expands. This technique also reveals the presence of a push-pull mechanism in specific structures. Insights into molecular dynamics and interactions are obtain through fluorescence spectroscopy
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The development of new semiconductor materials is one of the prime targets for the microelectronics industry. Tin disulphide (SnS2) is one such semiconductor material. It has a two dimensional layered structure which defines its chemical and physical properties. Currently no process has been developed to create SnS2 films with high structural quality at an industrial level. Chemical vapour deposition (CVD) is one technique that could offer an answer to this problem. To develop such a CVD process, it is necessary to have a good understanding of the mechanisms (nucleation and growth) that define said process. This dissertation, investigates the nucleation and growth of SnS2 using a SnCl4 / H2S CVD process for SnS2 on SiO2 wafers. The first part of experiments consists of the investigation of the temperature range in which SnS2 can be grown. To this end, Rutherford backscattering spectroscopy (RBS) is used to quantify the amount of deposited SnS2 . Various other techniques, e.g. Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM), are used to examine the composition, phase and morphology of the SnS2 samples. It is found that in a temperature range of 300 to 400 ◦C SnS 2 deposition is possible for a SnCl4 / H2S ratio of 1/10, and that at 400 ◦C the films show the best crystal orientation. The second part of experiments looks at the nucleation and growth of SnS2 for CVD at 400 ◦C. The growth at 400 ◦C is followed using a.o. atomic force microscopy (AFM) for deposition times from five seconds to half an hour. A growth model is proposed, which consists of two growth regimes. The first regime consists of the nucleation on the SiO2 substrate and growth of the formed grains up to an incomplete layer closure, with a preferential lateral growth. A delayed growth model is proposed describing the formation of amorphous 3D islands, followed by crystallisation and lateral growth. The second regime describes the formation of a rough SnS2 layer via a 3D-growth. This regime is characterised by the formation of pyramidal like spirals, combined with growth of holes in the SnS2 film. It is concluded that the growth rate is too high. The surface diffusion of adatoms and their lattice incorporation rate is too low, compared to the adsorption rate of adatoms, to allow SnS 2 to grow via a 2D mechanism. For that reason, it is proposed that the main focus of further research should be; to decrease the growth rate of SnS 2 , and thus allow a more controlled and 2D growth.
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The last few years gene therapy has been a very popular topic in modern medicine. It has the potential to treat a disease at the genetic level by replacing or counteracting a malfunctioning gene. However, for this the therapeutic genes have to overcome multiple cellular barriers to arrive at their target destination. Many viral and non-viral delivery systems have been developed to mediate this transfer and increase gene transfer efficiency. Recently polymers have gained a lot of attention as delivery systems because of their low immunogenicity and easy synthesis. Polycationic star polymers are one of those non-viral gene delivery systems. Via the ‘core first’ method these star polymers can be synthesized starting from a multifunctional initiator. Because of their large amount of reactive groups and high degree of branching, hyperbranched poly(arylene oxindole)s are a good choice for such a multifunctional initiator. In this work a hyperbranched poly(arylene oxindole) was synthesized via an A2 + B3 strategy. An isatin derivate with a hydroxyl function as well a derivative with a carboxylic acid function were tested in the polymerization reaction. Unfortunately, only polymerization using the isatin derivate with the carboxylic acid function lead to the formation of a hyperbranched polymer without significant side reactions occurring. Although the molecular weight and polydispersity should still be optimized for its application as a multifunctional initiator, some functionalization reactions with the polymer were already tested. For in vivo visualization the hyperbranched polymer was functionalized with a suitable fluorescing BODIPY dye. Therefore, the BODIPY core molecule was first synthesized and functionalized via palladium catalyzed C-H arylation to obtain the desired functional group for coupling. Next, this functionalized BODIPY was coupled with the polymer using a Mitsunobu reaction. Furthermore, an attempt was made to introduce an ATRP-initiator function into the polymer structure. These ATRP- initiator sites are necessary for its function as a macroinitiator in the synthesis of a star polymer. However, due to time shortage only one coupling reaction could be tested and this coupling reaction was unsuccessful.
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Starch, found in many plants, is a complex carbohydrate that serves as a source of energy. Next to the two main components: amylose (AM) and amylopectin (AP), it also has noncarbohydrate components present such as lipids, proteins, ... AM is a linear polymer containing α-(1,4)-glycosidic linkages that can form inclusion complexes with lipids or salicylic acid (obtained from sodium salicylate (NaSal)). AP, which is highly branched, also contains α-(1-6)-glycosidic linkages. Native maize starch has A-type crystallinity through the AP chains that are crystallized in a monoclinic lattice. The presence of these inclusion-complexes leads to V-type crystallinity. Upon heating starch in the presence of water, starch gelatinization occurs in which starch granules absorb water, swell, and burst, releasing AM and AP molecules into the medium. This will lead to the loss of their semi-crystalline structure which can be observed with small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD). The gelatinization temperature (Tgel) can change due to the amount of water present or certain additives, like glucose or NaSal. These changes can be monitored with differential scanning calorimetry (DSC). Glucose is known for increasing Tgel while the hydrotrope (NaSal), an organic molecule that enhances solubility, decreases it. The amount of water will change the shape of the DSC peaks. In excess water, only one peak is formed, G endotherm, while in limited water, two peaks are formed, G and M1 peaks. An M2 peak is seen in the presence of AM-inclusion complexes. This research can be interesting as starch is crucial in the food industry but also in e.g. medicines, glue, etc. The search for less sugar in food and baked goods is nowadays a ‘hot topic’, but the amount of sugar influences the gelatinization temperature which can alter the final baked product. For glues and the other mentioned industries, it can be beneficial to lower the gelatinization temperature (e.g. addition of NaSal) so no heating is required. This research shows transient gelatinization stages in excess and limited water conditions in which part of the semicrystalline blocklets are converted to fully gelatinized starch while others remain as layered stacks in which the dense layers are ordered like smectic liquid crystals. In excess water conditions granules in the transient stage rapidly convert into fully gelatinized starch. However, in limited water conditions, the gelatinization process is arrested up to when gelatinization is resumed at higher III temperatures. At first sight, the involvement of a liquid crystalline state aligns with the side-chain liquid crystalline polymer (SCLP) model. However, unlike the SCLP model, the G and M1 endotherms do not seem to be strictly coupled with a helix-helix dissociation and a subsequent helix-coil transition. The double melting behaviour under limited water conditions thus seems to be related to a temporary arrest rather than to a split into two mechanistically different gelatinization steps (dissociation and helix unwinding). As expected, glucose indeed raises the gelatinization temperature while NaSal decreases it down to room temperature when enough NaSal is added. The glucose molecules, that are dissolved in water, seem to penetrate the starch granules when the granules are submerged into the aqueous glucose solution.
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Spinrag is reeds lang bekend om zijn uitzonderlijke eigenschappen. De vezels zijn lichtgewicht en bezitten een hoge treksterkte. Recente publicaties overwegen gebruikt als optische vezel en een substituut voor kevlar. We weten dat ze zijn samengesteld uit eiwitten en dat deze verantwoordelijk zijn voor de unieke materiaaleigenschappen. De aminozuursequentie is goed gekend voor sommige types, terwijl anderen nog in detail te bepalen zijn. Alle onderzochte spinnenzijde vezels hebben een vergelijkbare quaternaire eiwitstructuur met collageen. Dit betekent dat de kristallijne en amorfe domeinen elkaar afwisselen en zorgen voor flexibiliteit, zonder hierbij afbreuk te doen aan de structurele integriteit. Hoewel deze vezels grondig werden bestudeerd met klassieke kristallografische technieken, zijn ze nooit het onderwerp geweest van een diepgaande niet-lineaire optica studie. Het succesvolle gebruik van niet-lineaire optica heeft onder meer als voordeel dat het monster geen verdere verwerking na verzameling vereist. In situ onderzoek is dus een mogelijkheid. De specifieke tak van de niet-lineaire optica waarvan gebruik wordt gemaakt in dit werk, is second harmonic generation, ook wel aangeduid als frequency doubling in literatuur. Om de beste niet-lineaire respons te verkrijgen, bepaalden we eerst de ideale fundamentele golflengte van de laserbundel. Ten tweede werd het effect van het variëren van de pulsbreedte, geassocieerd met de fundamentele golflengte bepaald. De resultaten gaven aan dat een geminimaliseerd pulsbreedte en een fundamentele golflengte van 800 nm optimaal waren, met betrekking tot de intensiteit van de niet-lineaire respons. Beide experimenten lieten ons toe de ideale instellingen van het lasersysteem te optimaliseren, zodoende kon de puntgoepsymmetrie van spinrag worden bepaald. We maakten gebruik van een nieuwe reeks tests om dit te doen. De bekomen symmetrie is achiraal. Dit resultaat is echter vrij onverwacht, want er bestaat weinig twijfel dat de vezels chirale structuren zijn. de eigenschap komt echter niet tot uiting in de metingen. De chirale respons wordt dus onderdrukt. Het laatste experiment onderzocht het effect van elongatie van de spindraad. Omdat de structuur zeer flexibel is, werden de effecten van de mechanische werking op de eigenschappen te bestudeerd. Dit gaf ons de kans om de veranderde niet-lineaire respons te bestuderen. Verandering kwam voor in de vorm van versterkte niet-lineaire respons intensiteit , Dit is waarschijnlijk een gevolg van de verbeterde uniforme kristalliniteit van de vezel die door elongatie. Het is kenmerkend dat de gegeneerde second harmonic generation afhankelijk is van de symmetrie van het staal. Dit komt zeer duidelijk tot uiting in dit werk. De randen van de vezels genereren altijd meer respons dan de kern van de vezel. De kern van enkele monsters vertoonde echter geen tekenen van niet-lineaire respons. Dit leidde tot de conclusie dat de aminozuursequentie in de kern van het spinrag geen fluorescerende moleculen bevat. Dit is een plausibele verklaring want de aminozuursamenstelling is variabel en de overheersende aminozuren alanine en glycine zijn niet fluorescerend .
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Microplastic pollution is one of the most critical environmental issues in the world right now. Many studies about human exposure to these micro-and nanoplastics (MNP) and the toxic effects they can cause are being conducted at this moment. Quantification and identification of these MNP lie at the bottom of solving this global problem. The most popular identification methods are Fourier-transform infrared spectroscopy and Raman spectroscopy. These techniques are lacking in non-destructive analysis with high sensitivity and low background noise. This thesis aims to develop an optical spectroscopy method to detect and identify microplastics after staining with Nile Red. The latter is a lipophilic solvatochromic dye. Staining will cause the particle to fluoresce, with its emission spectrum depending on its polarity. More polar plastics will have a more red-shifted emission maximum. Via hyperspectral analysis, the MNP can be identified based on this spectrum. Fluorescence lifetime imaging microscopy is also implemented. The fluorescence lifetime is the time that a fluorophore spends in the excited state, after absorbing a photon, before returning to the ground state. The lifetime depends on the fluorophore's micro-environment and therefore is also different for each MNP type. Differentiation is possible based on this lifetime value, but a graphical, fit-free phasor approach is also used. This allows for the mapping of the lifetime distribution in an image. When two different MNP types are present in one sample, they will each have a separate distribution cloud on the phasor plot, allowing for the graphical distinguishment of MNP. The plastics used are PP, PVC, HDPE, PET, and PS, these samples contain a range of shapes and sizes. A bought suspension of pure PS polymer particles of a fixed shape and size of 0,6 μm was also examined. The spectral data were processed in two ways. By calculating a ‘weighted average’ with the intensity values at each wavelength. This resulted in each MNP being attributed a weighted average value. After recording spectra of different particles, a statistical analysis, ANOVA and t-test, was done. This showed that the weighted averages of PP & HDPE and PS (self-made) & PVC do not differ significantly. The second option is through comparing the spectra themselves, using a relative similarity percentage. Because of the low similarity MNP gave when compared with themselves, only MNP with a significantly large similarity percentage could be distinguished. The same statistical tests were done on lifetime data. Measurements done on different particles of the same plastic showed that only HDPE & PET lifetimes did not differ significantly. Multiple measurements done on the same particle showed slightly different lifetimes. It could be concluded that HDPE & PET and PS (self-made and 0,6 μm) & PET cannot be differentiated. Finally, phasor plot analysis of samples containing two different plastics showed a possibility of recognizing MNP types based on the location of their phasor cloud on a phasor plot. When combining these two techniques, making use of the ’weighted average’ value and lifetime analysis, it could be possible to identify each plastic. The combination with similarly weighted averages, PP & HDPE give significantly different fluorescent lifetimes values and are possible to separate on a phasor plot. Still, both techniques have some flaws and improvement is possible.
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Fotokatalysatoren zoals zinkoxide zijn in staat om milieuverontreinigende stoffen af te breken na absorptie van voldoende energetisch licht. Een belangrijke beperking van dit fotokatalyse proces is de recombinatie van gegenereerde elektronen en gaten, wat resulteert in een verlies van fotokatalytische activiteit. Deze recombinatie wordt in dit onderzoek grotendeels voorkomen door afzetting van zilver nanopartikels op zinkoxide kristallen. De gegenereerde elektronen worden als het ware 'gevangen' in de zilver nanostructuren waardoor een verhoogde fotokatalytische activiteit wordt waargenomen. In een eerste fase worden twee reeds gepubliceerde procedures voor het genereren van ZnO microkristallen onder de loep genomen en verder verfijnd door verschillende parameters aan te passen. Op deze manier zijn drie zinkoxide microkristallen met een geschikte structuur voor dit onderzoek gesynthetiseerd: ZnO microrods [800 nm x 3,6 µm], ZnO microrods [1,5 µm x 2 µm] en ZnO staven [1 µm x 10 µm]. Deze ZnO kristallen verschillen in lengte, diameter en aanwezige kristalvlakken en hun structuur is uitvoerig door de scanning elektronenmicroscoop bestudeerd. Als vervolg worden zilver nanostructuren door middel van fotokatalytische reductie op de ZnO kristallen afgezet. Aan de hand van een fluorogene reactie wordt de fotokatalytische activiteit van de gesynthetiseerde halfgeleiders op bulk niveau bestudeerd. De reactie bestaat uit de fotoreductie van resazurine naar het fluorescente resorufine. Aan de hand van veranderingen in absorptie-eigenschappen en emissie-intensiteit van een resazurine oplossing in aanwezigheid van de katalysator, kan de efficiëntie van de fotokatalyse worden opgevolgd. Na afzetting van zilver nanostructuren op de zinkoxide kristallen wordt een meer efficiënte fotokatalysator verkregen gezien een twee- tot driemaal snellere katalytische omzetting kan worden waargenomen. In een laatste fase wordt de verhoogde fotokatalytische activiteit op 'single molecule' niveau onderzocht. Met een state-of-the-art geïntegreerde licht- en elektronenmicroscoop, worden de fotokatalytische omzettingen gecorreleerd met de oppervlakte-eigenschappen van de ZnO-zilver halfgeleiders. Zowel de 'in situ' zilverafzetting als de katalyse van de fluorogene reactie worden bij de drie gesynthetiseerde ZnO microkristallen geanalyseerd. Op het oppervlak van de ZnO microrods [800 nm x 3,6 µm] en ZnO staven [1 µm x 10 µm] worden dendriet- en plaatvormige zilverstructuren gevormd. Uit de overlap van de fotokatalytische activiteitsmappen met de structurele informatie via SEM blijkt dat de meeste activiteit wel degelijk op deze zilverstructuren is gelokaliseerd.
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Semiconductors and semiconductor materials have proven themselves to be an integral cornerstone of modern technological achievements and advancements. From the first transistors to the cutting-edge solar cells and LEDs of today, they have revolutionised materials science and engineering. In pushing for materials with higher efficiencies, superior opto-electronic properties and longer operational lifetimes, perovskites have risen to the forefront of semiconductor developments. Leading to record-breaking efficiencies in devices, this class of materials is being extensively researched. Recently many groups have started focussing on lead halide perovskites (LHPs) for use in LEDs due to their excellent properties such as high colour purity, remarkable efficiencies, solvent processability and compositional tuneability. Developments in LHPs have already provided highly efficient and relatively stable green LEDs while those of blue LEDs remain lacking. Red LEDs achieve high efficiencies but experience low operational lifetimes, limiting their use. The most common material used in red LEDs, caesium lead iodide (CsPbI3), has an inherent phase instability issue caused by the formation of non-active yellow phase at room temperature under the influence of both moisture and oxygen. A recent approach to remedying this issue is by synthesizing CsPbI3 nanocrystals. These are nanoparticles ranging from 2-20 nm in size and thus have a significantly higher surface to volume ratio; allowing for surface stabilisation methods to be employed. Long chain organic ligands are added to the synthesis which can attach to the nanocrystal surface after synthesis, encapsulating the ionic perovskite structure in an apolar organic shell, preventing moisture from entering and degrading the crystal while at the same time increasing efficiencies by filling in surface defects. The apolar shell around the nanocrystals also makes solvent processability possible since the nanocrystals can be dispersed in a solvent like hexane. This suspension can then be used to print thin films of the semiconducting material, greatly cutting fabrication costs. In this research new diammonium dopants were utilized in the synthesis of CsPbI3 nanocrystals, butanediammonium (BDA) and propanediammonium (PDA). Their ammonium group and its hydrogen bonding properties have previously been shown to lead to increased efficiencies and stabilities in perovskite materials. The doped particles were successfully prepared using the hot injection method, a technique well suited for delivering nanocrystals with narrow particle size distributions. The resulting nanocrystal suspensions were used to coat glass coverslips to measure their photoluminescence (PL) and UV-Vis spectra and left to age over a period of 9 weeks to investigate the long-term stability. UV-Vis confirmed a superior phase stability of BDA doped nanocrystals, especially in 2% and 5% molar concentrations, with yellow phase peaks appearing weeks later than in normal CsPbI3. It 4 was also found that BDA doping led to films with blue shifted emissions in 2% and 5% molar percentages while not affecting PL position in 10% concentration. The former two samples however, also showed an increase in emission width. PLQY measurements performed after synthesis also show a decrease in quantum yields to undoped CsPbI3. XRD was performed on a thin NC film and showed no change in peak position, meaning the cation did not integrate into the structure. The change
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Carbon fibers are used in a broad area of applications in which a strong and lightweight material is needed. Reduction of the weight without diminishing the strength can contribute to a more sustainable environment by reducing the fuel consumption. However, the production of these materials comes at a high cost, making large scale industrial applications not feasible yet. The current production process, which starts from polyacrylonitrile (PAN), is expensive and has a severe impact on the environment. The monomer acrylonitrile (AN) is very toxic and the production of the actual carbon fiber requires high temperatures. In the past decades a lot of research has been done on looking for alternative precursor materials among others lignin, cellulose, polyethylene. Their applicability is limited, because the final mechanical properties of the carbon fibers are inferior to the current PAN-based carbon fibers. Alternatives that can reach a certain minimal strength value can be used to fill in the gap of rapidly growing market of low-end applications, where it is not required to utilize high end fibers. This project mainly focused on polyethylene-like precursor polymers as possible alternatives. Synthesis of the polymers was done via ring-opening metathesis polymerization of eight-membered rings whether or not substituted with functional groups. The investigated functionalities are the hydroxyl, epoxide and nitrile group and also a photoinitiator moiety. The amount of double bonds in the polymer could be changed by choosing different monomers such as cyclooctene and cyclooctadiene. Both the degree of functionality and the amount of double bonds were investigated regarding carbon yield by making copolymers with functionalized and non-functionalized monomers. The synthesized polymers are characterized and their thermal stability is researched in the second part of this work. Characterization showed that some polymers underwent stabilization reactions during heat treatment in air. Thermal crosslinking was observed and leads to the formation of carbonized material that is stable at high temperatures. Experiments showed that prestabilization should always be performed in air, because no stabilized fiber is formed in nitrogen atmosphere. Proper stabilization of the fibers requires very slow heating rates and new methods need to be found to accelerate this process. Looking at the degree of functionalization shows that higher amounts of functional groups leads to a decrease in melting point and crystallinity, which could be disadvantageous for the final carbon yield. It is important to have a polymer with a high degree of crystallinity and a melting point that is higher than the temperature needed for thermal crosslinking. All these problems can possibly be avoided with the addition of a photoinitiator, which can be activated by irradiation with UV light. Polymers can form crosslinks without applying heat so that the precursor fiber stays in the solid state. This approach requires further research and can possibly lead to even higher carbon yields, making it a worthy alternative.
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In de maatschappij van nu is een leven zonder polymeren niet in te beelden, maar toch heeft het woord “polymeer” een slechte connotatie. Ondanks de slechte reputatie van polymeren wordt het elke dag gebruikt in elk huishouden en is het ook aanwezig in vele industriële processen. Deze polymeren bestaan uit bouwstenen die aan elkaar gekoppeld zijn en zo een ketting vormen. Door de natuur geïnspireerd hebben polymeer chemisten om perfecte controle te krijgen over de sequentie van deze bouwstenen in de ketting (sequentie gedefinieerde polymeren). Verscheidene methoden zijn ontwikkeld om deze sequentie gedefinieerde polymeren te synthetiseren. Meer recent is de focus verschoven naar polymeren die bestaan uit een afwisselende enkele en dubbele binding, omdat deze aantrekkelijke elektronische eigenschappen bevatten. Deze worden geconjugeerde polymeren genoemd. In deze thesis is een nieuwe strategie ontwikkeld om geconjugeerde polymeren te ontwikkelen met een perfecte controle over de sequentie van de bouwstenen wat sequentie gedefinieerde geconjugeerde polymeren (SDCP) wordt genoemd. Deze strategie gebruikt twee verschillende reacties om de bouwstenen aan elkaar te koppelen. Bij elke reactie wordt de ketting met één monomeer verlengt waarbij telkens een differentiatie kan ingebouwd worden. Dit zal gedaan worden door gebruik te maken van twee verschillen zijketens. Voor de reacties zijn er twee verschillend bouwstenen nodig, dus voor elke zijketen zijn er twee nodig en in het totaal moeten er dus vier verschillende bouwstenen worden gemaakt. Extra bouwstenen zijn nog nodig om de synthese van de SDCPen te starten (startblok). Deze startblokken bezitten maar één dat kan reageren in één van de reacties en een andere plaatst is beschermd. Hierna kan één van de reactie gebruikt worden om een startblock te koppelen aan een bouwsteen dat kan verder koppelen met een ander bouwsteen via de andere reactie. De twee reactie worden alternerend gebruikt om een grote ketting te bouwen (SDCP). De vier bouwstenen zijn succesvol gesynthetiseerd alsook twee efficiënte startblokken. Één van deze startblokken kan reageren in de ene reactie en de andere startblok kan reageren in de andere reactie. Het eerste startblok is succesvol gekoppeld met twee extra bouwstenen maar dit resulteerde in de vorming van een mengeling van twee producten en de opzuivering van de eerste reactie was zeer langdurig. Het andere startblok is succesvol gekoppeld met een bouwsteen en was gemakkelijk op te zuiveren. Nadien kon de bescherming van het startblok er ook gemakkelijk afgehaald worden.
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