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"Chain walking” catalytic polymerization CWCP is a powerful tool for the one-pot synthesis of a unique class of hyperbranched polyethylene HBPE-based macromolecules with a controllable molecular weight, topology, and composition. This dissertation focuses on new synthetic routes to prepare HBPE-based macromolecular architectures by combining the CWCP technique with ring opening polymerization ROP, atom–transfer radical polymerization ATRP, and “click” chemistry. Taking advantage of end-functionalized HBPE, and a new ethynyl-soketal star-shape agent, we were able to synthesize different types of the HBPE-based architectures including hyperbranched-on-hyperbranched core-shell nanostructure, and miktoarm-star-HBPE-based block copolymers. The first part of the dissertation provides a general introduction to the synthesis of polyethylene types with controllable structures. Well-defined polyethylene with different macromolecule architectures were synthesized either for academic or industrial purposes. In the second part, the HBPE with different topologies was synthesized by CWCP, using a α-diimine Pd (II) catalyst. The effect of the temperature and pressure on the catalyst activity and polymer properties, including branch content, molecular weight, distribution, and thermal properties were studied. Two series of samples were synthesized: a) serial samples (A) under pressures of 1, 5, and 27 atm at 5˚C, and b) serial samples (B) at temperatures of 5, 15, and 35 ˚C under 5 atm. Proton nuclear magnetic resonance spectroscopy, 1H NMR, and gel permeation chromatography, GPC, analysis were used to calculate the branching content, molecular weight, and distribution, whereas differential scanning calorimetry, DSC, was used to record the melting and glass transition temperatures as well as the degree of the crystallinity. Well-defined HBPE-based core diblock copolymers with predictable amphiphilic properties are studied in the third part of the project. Hyperbranched polyethylene-b-poly(N-isopropylacrylamide), HBPE-b-PNIPAM, and hyperbranched polyethylene-b-poly(solketal acrylate), HBPE-b-PSA, were successfully synthesized by combining CWCP and ATRP. The synthetic methodology includes the following steps; a) synthesis of multifunction hyperbranched polyethylene initiators HBPE-MI by direct copolymerization of ethylene with 2-(2-bromoisobutyryloxy)ethyl acrylate BIEA in the presence of a α-diimine Pd(II) catalyst, and b) HBPE-MI with α-bromoester groups used as initiation sites for ATRP. Proton nuclear magnetic resonance spectroscopy, 1H NMR, gel permeation chromatography,GPC, and Fourier transform infrared, FT-IR, spectroscopy, were used for determining the molecular and composition structures. Also, differential scanning calorimetry, DSC, and thermogravimetric analysis, TGA, were used to record the melting temperature and to study the thermal stability, respectively. In the fourth part, a well-defined 3-miktoarm star copolymer 3μ-HBPE(PCL)2 (HBPE: hyperbranched polyethylene, PCL: poly(ε-caprolactone) was synthesized by combining CWCP, ring opening polymerization, ROP, and “click” chemistry. The synthetic methodology includes the following steps: a) synthesis of azido-functionalized hyperbranched polyethylene HBPE-N3 by CWCP of ethylene with the α-diimine Pd(II) catalyst, followed by quenching with an excess of 4-vinylbenzyl chloride and transformation of –Cl to the azido group with sodium azide, b) synthesis of in-chain ethynyl-functionalized poly(ε-caprolactone), (PCL)2-C≡CH by ROP of ε-CL with ethynylfunctionalized solketal [3-(prop-2-yn-1-yloxy) propane-1,2-diol] as a bifunctional initiator, in the presence of P2-t-Bu phosphazene super base, and c) “clicking” HBPE-N3 and (PCL)2-C≡CH using the copper(I)-catalyzed alkyne–azide cycloaddition CuAAC. Proton nuclear magnetic resonance spectroscopy, 1H NMR, gel permeation chromatography, GPC, and Fourier transform infrared, FT-IR, spectroscopy, were used to determine the molecular and composition structures. Also, the differential scanning calorimetry, DSC, was used to record the melting point temperature. The fifth part illustrates the self-assembly behavior of the HBPE-based block copolymers of poly(N-isopropylacrylamide), NIPAM, and poly(ε-caprolactone), PCL, at room temperature in water and a petroleum ether-selective solvent for NIPAM and PCL respectively. The synthesized copolymers HBPE-b-NIPAM and 3μ-HBPE(PCL)2 revealed either core-shell nanostructure in vesicles or worms and worm-likes branches, as confirmed by combining the analysis of dynamic light scattering, DLS, transmission electron microscopy, TEM, and atomic force spectroscopy, AFM. All the findings presented in this dissertation emphasize the utility of "living" CWCP to synthesize end-functionalized HBPE, and new star-linkage HBPE-based complex architectures. The summary and future works concerning predictable properties and applications are discussed in the sixth part.

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The use of volatile organic compounds (VOC) in coating materials has adverse effects on both human health and the environment. Due to concern over these problems, coating industry has attempted to decrease the solvent contents of coating materials for the last three decades by developing water dispersed and powder paints. A recently developed method to make solvent free paint is to use highly branched polymers in high solid alkyd resins. Highly branched polymers help to achieve resins with viscosity much lower than its linear counterparts. In this study, a new alkyd based resin was formulated using long oil alkyd and melamine based hyperbranched polymer having 24 functional groups on its structure. The long oil alkyd was synthesized by using an oil mixture (40% linseed + 60% sunflower). Melamine was preferred as core molecule due to its excellent properties such as greater hardness, alkali and solvent resistance with thermal stability. The resin produced has low viscosity because its hyperbranched structure / therefore, it needs no solvent for its application. The chemical characterization of the resins with different compositions was performed using Fourier Transform Infrared Spectroscopy and thermal properties were determined by Differential Scanning Calorimetry. Physical and mechanical tests were conducted to determine hardness, flexibility, impact resistance, abrasion resistance, adhesion power, and gloss property of the samples. The viscosity of the resins decreased from 148 Pa.s to 8.84 Pa.s as the hyperbranched polymer to long oil alkyd ratio was increased from 1:3 to 1:24. On the other hand, the hardness values of the resins decreased from 198 Persoz to 43 Persoz. All resins showed excellent flexibility, formability, adhesion, and gloss.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22014号 / 工博第4626号 / 新制||工||1721(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 山子 茂, 教授 辻井 敬亘, 教授 竹中 幹人 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

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Ring-opening metathesis polymerization (ROMP) is a great tool for synthesizing polyolefin materials with different topologies, including hyperbranched polymers—polymers with high degrees of branching and many end groups. However, hyperbranched polymer synthesis via ROMP is challenging due to multifunctional-monomer or multi-polymerization requirements. To simplify the synthesis of hyperbranched ROMP polymers, we developed a new synthetic approach: Self-condensing ROMP. The self-condensing ROMP approach involves a ROMP initiator modification to attach a ROMP-polymerizable group (a ROMP monomer), producing a ROMP "inimer" (initiator + monomer). The ROMP inimer initiates the polymerization and becomes a branching unit in the polymer structure, resulting in single-step hyperbranched polymer synthesis. The key challenge is controlling of this approach the ROMP initiator reactivity to avoid initiating polymerization during the ROMP inimer synthesis. Well-defined ruthenium-based olefin metathesis catalysts are common ROMP initiators due to their high stability, reactivity, and functional group tolerance. Thus, we studied the olefin metathesis catalyst activation temperature to enable ROMP initiator-monomer coupling. Based on the catalyst activity, we designed and synthesized a series of ROMP inimers. Then, we synthesized hyperbranched polymers via self-condensing ROMP. The characterization of hyperbranched polymers indicated the effect of branching density on the physical properties of the polymer. This approach introduced a new class of olefin metathesis complexes, ROMP inimers, containing both the initiator and propagating center. This approach provides a way to synthesize hyperbranched polymers from any known ROMP monomers in a single step. This dissertation also includes the synthesis and characterization of a bimetallic Ru complex that could directly synthesize cyclic polyolefin. We also include the synthesis and characterization of copper-ruthenium bimetallic olefin metathesis catalysts. / Doctor of Philosophy / Hyperbranched polymers are a class of polymers having highly branching structures and functional end-groups, and presenting distinct physical and chemical properties compared with linear polymers. Hyperbranched polymers have been used for many applications including processing additives, cross-linkers, compatibilizers, and catalyst supports. Well-defined ruthenium-based olefin metathesis catalysts enable the synthesis of materials with different topologies, functionalities, and chemical and physical properties via ring-opining metathesis polymerization (ROMP). Ligand modifications on ruthenium catalysts have been applied to improve the catalyst stability and reactivity. However, this dissertation modifies olefin metathesis catalysts to synthesize hyperbranched polymers in a single step. This dissertation illustrates catalyst functionalization with a ROMP monomer moiety to synthesize a ROMP inimer (inimer= initiator + monomer). The ROMP initiator—olefin metathesis catalyst—and ROMP monomer coupling produces an "inimer". The inimer can undergo self-condensing ROMP with a ROMP monomer addition to synthesize hyperbranched polymers. This approach introduced a new class of olefin metathesis complexes containing both the initiator and propagating center. This approach also provides a way to synthesize hyperbranched polymers from any known ROMP monomers in a single step.

In 1980’s a new class of material named as dendrimer became popular both in the field of polymer science and engineering. Dendrimer is an example of symmetric, highly branched three dimensional globular nano-object. It possess several interesting physical and chemical properties like low solution and melt-viscosity, lower intermolecular chain entanglement, large number of end groups placed at the molecular periphery, relatively high solubility with respect to their linear counterpart. In order to get this perfectly branched structure, one has to go through the tedious multistep synthetic approach, repetitive chromatographic purification and protection-deprotection strategies in every step; all of which limits the large scale production and thus commercialization. On the other hand, hyperbranched polymer, a highly branched analogue of dendritic polymer with few defects in their branching architecture, which can be prepared in a single step, show similar physical and chemical properties as that of dendrimer. Polymerization of AB2 monomer is one of the well established method to generate hyperbranched polymer which upon polymerization, generates plenty of ‘B ’groups at the periphery along with a single ‘A’ group as a focal point in the resulting hyperbranched polymer as shown in Figure 1. From the structural point of view, hyperbranched polymers consist of three distinctly different compartments such as periphery, interior and a (single) focal point. During the past decade our lab have developed a novel melt trans-etherification process to generate polyethers and have utilized to access to a wide variety of hyperbranched structures. One of the challenges we addressed is to selectively functionalize the periphery of the hyperbranched polymer during the polymerization process. Polycondensation of ‘AB2’ monomer is not sufficient enough to generate a wide variety of hyperbranched polymer as the periphery of hyperbranched polymer is limited to the ‘B’ functional group unless it could be modified via ‘post-polymerization modifications’. Copolymerization of ‘AB2’ monomer with stoichiometric amount of ‘A-R’ monomer should result in hyperbranched polymer decorated with ‘R’ groups in the periphery that can be prepared in a single step. One of the prerequisite in the ‘AB2+A-R’ approach is that the comonomer ‘A-R’ should have silent ‘R’ group which does not interfere during the polymerization. During the copolymerization process with stoichiometric amount of ‘A-R’ monomer, ‘AB2’ monomer having one equivalent excess of ‘B’ can react with the ‘A’ group from ‘A-R’ monomer eventually generating the hyperbranched structure with peripheral ‘R’ groups. By appropriately choosing the ‘R’ group, one can access a wide class of hyperbranched polymer with the required functionality. Further by having a reactive ‘R’ group that is not participating in polymerization can act as a handle for post-polymerization modifications. For instance, copolymerization of 1-(6-Hydroxyhexyloxy)-3,5-bis(methoxymethyl)-2,4,6-trimethylbenzene (Hydroxy as ‘A’ and methoxy as ‘B’) and 6-bromo-1-hexanol where ‘OH’ and ‘-(CH2)6Br’ is ‘A’ and ‘R’ functional groups respectively, generates hyperbranched polymer with peripheral alkyl bromide functional groups as shown in Figure 2. The peripheral alkylbromides has been quantitatively transformed to quaternary ammonium or pyridinium salts using trimethyl amine or pyridine respectively. Thus by the post polymerization modification, we have transformed a hydrophobic hyperbranched polymer to a water soluble cationic hyperbranched polymer by simple and efficient post-polymerization modification. In a slightly different objective we Another problem that I have addressed is the difficulty associated with the aforementioned copolymerization approach. In spite of the fact that stoichiometric amounts of ‘A-R’ type monomer was taken in ‘AB2 + A-R’ approach, the extent of peripheral functionalization i.e. the incorporation of ‘R’ group is relatively lower. Further the molecular weight of the hyperbranched polymer obtained is also not high. One of the reasons we adopted ‘AB2 + A-R’ approach is to provide a functional handle for the subsequent post-polymerization modification. We modified the ‘AB2’ type monomer with a functionalizable handle to circumvent the lower amount of incorporation of the ‘A-R’ type monomer in ‘AB2 + A-R’ approach. Of all the readily functionalizable handles, click chemistry found to be a very useful tool for the post-polymerization modifications as the reactions conditions are mild, no side product, high selectivity, easy purification, etc. Another advantage of this reaction is that, we can incorporate any type of functional group starting from a single clickable parent hyperbranched polymer. In this particular project, I have Earlier design of the ‘AB2’ type monomer in our group, to prepare hyperbranched polymer via melt transetherification process, involved benzylic methoxy groups as ‘B’ in ‘AB2’ monomer leading to a hyperbranched polymer with peripheral methoxy groups. Transetherification under melt-conditions is an equilibrium reaction which was driven towards the hyperbranched polymer by continuous removal of methanol from the system as a volatile alcohol. In the new design of ‘AB2’ monomer; we have used benzylic allyloxy groups as ‘B’ in ‘AB2’ monomer, where in polymerization is driven by the continuous removal of allyl alcohol (instead of methanol as in the previous case), generates hyperbranched polymer with peripheral allyloxy group containing hyperbranched polymer. The allyloxy groups can be subsequently functionalized with a variety of thiol, we prepared a hydrocarbon-soluble octadecyl-derivative, amphiphilic systems using 2-mercaptoethanol and chiral amino acid (N-benzoyl cystine) hyperbranched structures by using thiol-ene click reactions (Figure 3). Polymers prepared from the parent hyperbranched polymer have significantly different physical properties like glass transition temperature (Tg), melting point (Tm) etc; thus considering the versatility of functionalization, parent polymer could be envisioned as a clickable hyperscaffold. More interestingly by functionalizing cystine derivative, we have demonstrated the possibility of biconjugation of the hyperbranched polymer. In summary, the limitations of ‘AB2+A-R’ copolymerization approach (low molecular weight Molecular weight and molecular weight distribution are very important parameters that influence the physical property and thus the application of the polymeric materials. As predicted by Flory, hyperbranched polymers are inherently polydisperse in nature and it tends to infinity when the percent of conversion is very high. Experimentally observed value of polydispersity is also significantly higher compared to their linear analogues. Control of the molecular weight and polydispersity of hyperbranched polymer by using a suitable amount of reactive multifunctional core has been demonstrated in this project. We have substantiated by using very little amount of ‘B3’ core along with ‘AB2’ monomer; wherein ‘B’ in ‘B3’ are more reactive than ‘B’ in ‘AB2’ monomer, regulate the molecular weight and polydispersity of the resulting hyperbranched polymer. As the ratio of core to monomer increases the molecular weight and polydispersity reduces in nearly linear fashion. In a slightly different objective, the core and periphery are functionalized with two different fluorophore by using orthogonal click reactions and demonstrated the possibility of energy transfer from periphery to the core of the hyperbranched polymer. In this section of my thesis, the self-assembly behavior of a periodically grafted amphiphilic copolymer has been studied. Polymer was synthesized via melt transesterification approach where hexaethylene glycol monomethyl ether (HEG) containing diester monomers are reacted with alkylyne diol monomers with varying carbon spacer (C12 and Another interesting problem, I approached is to functionalize the interior part of the hyperbranched polymer. In the case of dendrimer, as it is a step-wise synthesis, internal functionalization could be accomplished with the order of monomer addition i.e. by putting the internal functional group containing monomer first followed by other monomer not having those functional groups, whereas it is a bit challenging task for hyperbranched polymers especially when dealing with polycondensation of AB2 monomers, as it is a single step polymerization process. For a hyperbranched polymer in the polycondensation of ‘AB2’ monomer, the internal functional group should reside in between of the ‘A’ and ‘B’ functional group wherein the internal functional groups are silent during the process of polymerization. In order to do so, we have designed and synthesized a new AB2 monomer (a in Figure: 4). Here decanol is the volatile condensate that was removed during the transetherification reactions leading to a hyperbranched polymer having allyl group as the internal functional group and decyloxy as the peripheral functional group (b in Figure: 4). As a post-polymerization modification, the interior allyl groups were modified by thiol-ene click reaction with variety of thiol derivatives. In one example, the inherent hydrophobic nature of the parent hyperbranched polymer which is enhanced by the decyl chain at the molecular periphery, is converted to a alkaline water soluble hyperbranched polymer by the click reaction with mercapto succinic acid (d in Figure: 4) or mercapto propionic acid (c in Figure: 4) to the internal allyl groups, generating a novel amphiphilic hypersystem. This kind of amphiphilic systems are very interesting to study for their self-assembly behavior, in this particular case, the modified hyperbranched polymer adopts as a large spherical aggregates in alkaline water evidenced by FESEM (Figure: 4) and AFM images. Further investigation is being carried out to understand the exact nature of these aggregates. As the hyperbranched polymer contained ‘-S-‘ group in the interior, we utilized this as the scaffold for scavenging heavy metal ions like Hg2+ from aqueous solutions to the chloroform solution containing polymer. This hyperbranched polymer could trap Hg2+ ions even when present in ppm level of contamination.

L’objectif de ce travail est dans un premier temps d’élaborer des fleurs macromoléculaires et des polymères hyperbranchés par auto-assemblage et réticulation de copolymères triblocs associatifs en solvants sélectifs. Dans un second temps, il s’agit d’étudier les propriétés structurales et dynamiques de ces architectures par diffusion de la lumière et rhéologie en solution sur une gamme étendue de concentration. La première partie de ce travail a consisté à synthétiser les copolymères triblocs associatifs à base de polybutadiène (PB), et de poly(oxyde d’éthylène) (POE) en les modifiant aux extrémités avec des blocs solvophobes réticulables respectivement poly(acrylate de diméthylmaléimidoéthyle)(PMDIEA), et poly(acrylate de méthacryloyloxyéthyle)(PAME). La deuxième partie de ce travail a consisté en l’élaboration de micelles "fleurs" et de polymères hyperbranchés (HyperMac) par auto-assemblage dans l’eau du copolymère PAME7-b-POE270-b-PAME7, suivi d’une réticulation des cœurs afin de figer les structures. Il a été observé par diffusion de la lumière que la taille dépend de la concentration à laquelle le polymère a été réticulé. Les dynamiques locales ainsi que la compressibilité osmotique sont indépendantes de l'architecture (étoile, fleur ou HyperMac) à forte concentration. Il a également été observé une autosimilarité des structures obtenues quels que soient leurs types. Les mesures de rhéologie montrent une augmentation de la viscosité avec la taille et le degré de ramification des architectures. La dépendance en concentration de la viscosité des solutions de "fleurs" est identique à celle des solutions d'étoiles. / The objective of this work is a first step to develop flower-like and hyperbranched polymers by selfassembling and crosslinking of associative triblock copolymers in selective solvents. The second aim is to study structural and dynamic properties of these architectures in solution by light scattering and rheology on a broad range of concentrations. The first part of this work consisted in synthesizing triblock copolymers based on polybutadiene (PB), and poly(ethylene oxide) (PEO) by end-capping them with crosslinkable solvophobic blocks; poly(dimethyl maleimido ethyl acrylate) (PDMIEA) and poly(methacryloyloxyethyl acrylate) (PMEA), respectively. The second part of this work consisted in elaborating flowers-like and hyperbranched polymers (HyperMac) by self-assembling the PAME7-b-PEO270-b-PAME7 copolymer in water, followed by crosslinking the micelles cores in order to freeze the structures. Light scattering revealed that the size of the objects depended on the concentration at which the polymers were crosslinked. Local dynamics and osmotic compressibility were independent of the architecture (star, flower or HyperMac) at high concentrations. In addition, a self-similarity of the structures was observed regardless their types. Rheology measurements showed an increase of viscosity with the size and the branching degree of the architectures. The concentration dependence of the viscosity was the same for star- and flower-like polymer in water.

We grow AB₂ random hyperbranched polymer structures in different ways and using different simulation methods. In particular we use a method of ad hoc construction of the connectivity matrix and the bond fluctuation model on a 3D lattice. We show that hyperbranched polymers split into two universality classes depending on the growth process. For a “slow growth” (SG) process where monomers are added sequentially to an existing molecule which strictly avoids cluster–cluster aggregation the resulting structures share all characteristic features with regular dendrimers. For a “quick growth” (QG) process which allows for cluster–cluster aggregation we obtain structures which can be identified as random fractals. Without excluded volume interactions the SG model displays a logarithmic growth of the radius of gyration with respect to the degree of polymerization while the QG model displays a power law behavior with an exponent of 1/4. By analyzing the spectral properties of the connectivity matrix we confirm the behavior of dendritic structures for the SG model and the corresponding fractal properties in the QG case. A mean field model is developed which explains the extension of the hyperbranched polymers in an athermal solvent for both cases. While the radius of gyration of the QG model shows a power-law behavior with the exponent value close to 4/5, the corresponding result for the SG model is a mixed logarithmic–power-law behavior. These different behaviors are confirmed by simulations using the bond fluctuation model. Our studies indicate that random sequential growth according to our SG model can be an alternative to the synthesis of perfect dendrimers.