A study has been made on the irradiation induced grafting of MMA to PPE and cellulose subtrates in the presence of various solvents and Irgacure 819 photoinitiator, a new photoinitiator on the market at the commencement of this project. UV is the main irradiation source used. The grafting yields have been found to vary with parameters such as the subtrate types and thickness, MMA concentration, solvents used, Irgacure 819 concentration and UV doses. For the cellulose subtrate, good grafting yields were obtained only when solvents such as methanol and DMF were used. On the contrary, MMA could graft to PPE with or without solvents, although high grafting yields were achieved in the presence of methanol, DMF and other chlorinated solvents. The solvent effects on the grafting process of MMA to PPE and cellulose subtrates were attributed to the wetting and swelling effects by the solvents as well as the Trommsdorff effect. During the course of this study, a comparison in the performance between Irgacure 819 and other photoinitiators (PIs) was also carried out. A study was made of the UV radiation induced grafting of styrene to PPE subtrate with EP vinyl monomers and vinyl ethers as comonomers. The possibility of spontaneous polymerization of styrene/EP vinyl monomer mixtures under the influence of UV radiation was also investigated. Grafting yields were found to vary with the comonomer types and their concentrations, the presence or absence of solvents and additives such as Irgacure 819 photoinitiator, K185 cationic photoinitiator, mineral acids and CT complexes. In addition, the composition of grafted subtrates was studied by using the FT-IR spectroscopy technique / Doctor of Philosophy (PhD)

The purpose of this research was to synthesize the constrained geometry catalyst Ti[(C5Me4)SiMe2(tBuN)]Cl2 (1) with MAO as a cocatalyst for ethylene homopolymerization and copolymerizations with 1-TMSO-alkenes to produce a copolymer with polar functionality. Three 1-alkenols of varying length were purchased and derivatized and used for the copolymerization experiments: 2-propen-1-ol, 3-buten-1-ol and 9-decen-1-ol. Several variables were tested to determine their effects on comonomer incorporation such as temperature, equivalents of comonomer, equivalents of MAO and two different solvents. Higher catalytic activities were correlated with fewer equivalents of polar comonomer, lower temperatures, and no fewer than 1000 equivalents of MAO. Toluene was found to be a far more effective reaction solvent than dichloromethane, as polymer yields were on average thirteen times higher. All polymer samples were analyzed by high temperature 1H NMR spectroscopy and selected samples were analyzed by DSC and IR spectroscopy. DSC determined that the polyethylene produced by 1 was substantially linear HDPE with long chain branching and that comonomer incorporation reduced the Tc and Tm, probably due to increased short chain branching. 1-TMSO-9-Decene was the most effective comonomer, as it had the highest incorporation rates (8.0 mol%) of all three of the polar comonomers. The two shorter comonomers exhibited no incorporation at all. This confirmed the hypothesis that polar comonomers with longer chains would be less prone to poisoning the electrophilic catalyst. / Thesis (Master, Chemistry) -- Queen's University, 2009-04-27 10:16:46.356

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This dissertation demonstrates the preparation of blocky brominated syndiotactic polystyrene (sPS-co-sPS-Br) copolymers with tailored chain sequences using a simple, post-polymerization functionalization method conducted in the heterogeneous gel state, and investigates the effect of sPS reaction state and sPS/solvent gel morphology on the copolymer microstructure and thermal properties. Gel-state (Blocky) brominated copolymers were prepared from a 10 w/v% sPS/carbon tetrachloride (CCl4) gel and a 10 w/v% sPS/chloroform (CHCl3) gel in a matched set containing 6−32 mol% p-bromostyrene (Br-Sty) units. For comparison, a matched set of randomly brominated copolymers was prepared using a homogeneous solution-state (Random) reaction method and a set of brominated copolymers was prepared using a heterogenous powder-state (Powder) reaction method. The degree of bromination was evaluated using 1H nuclear magnetic resonance (NMR) spectroscopy. Powder-state bromination produced copolymers with a limited degree of functionalization of up to 12 mol% Br and required a threefold longer reaction time than the gel-state method conducted on the sPS/CHCl3 gel, demonstrating that the powder-state method is time-consuming and the dense sPS powder is incapable of producing copolymers with high Br-content. Microstructural characterization provided by 13C NMR spectroscopy, showed that bromination of sPS produces multiple peaks in the quaternary carbon region of the NMR spectrum, signifying through-bond communication between neighboring styrene and Br-Sty monomers. This work provides the first high-resolution comonomer sequencing of brominated sPS copolymers. Characterization of the quaternary carbon spectrum, assisted by band selective gradient heteronuclear multiple bond correlation (bsgHMBC) spectroscopy, electronic structure calculations, and simulated statistically random copolymer chains, revealed that each resonance peak could be assigned to a styrene or Br-Sty unit that exists in the center of a unique sequence of five monomers (i.e., a pentad) along the copolymer chain (e.g., ssssb where s = styrene and b = brominated styrene). Our comonomer sequencing method demonstrated that the Blocky and Powder copolymers have block-like character. Remarkably, the Blocky copolymers exhibit notably higher degrees of blockiness and larger fractions of sssss and bbbbb pentads at low Br contents (i.e., 32 mol% Br), relative to the Powder copolymers, confirming their blocky microstructure. Quenched films of the Blocky copolymers, analyzed using ultra-small-angle (USAXS) and small-angle X ray scattering (SAXS), show micro-phase separated morphologies that are reminiscent of conventional block copolymer phase behavior, supporting that the Blocky copolymers contain distinct segments of pure sPS and segments of randomly brominated sPS. Crystallization behavior of the copolymers, examined using differential scanning calorimetry (DSC), demonstrates that the Blocky copolymers are more crystallizable and crystallize faster at lower supercooling compared to their Random analogs. Simulations of blocky copolymers were developed based on the semicrystalline gel morphology to rationalize the effect of gel-state functionalization on copolymer microstructure and crystallization behavior. The simulations confirm that restricting the accessibility of the brominating reagent to monomers well removed from the crystalline fraction of the gel network produces copolymers with a greater prevalence of long runs of pure sPS that is advantageous for preserving desired crystallizability of the resulting blocky copolymers. To investigate the effect of sPS/solvent gel morphology on copolymer microstructure and crystallization behavior, the sPS/CCl4 and sPS/CHCl3 copolymers were compared directly. Characterization of the sPS/solvent gels using USAXS/SAXS, revealed that the gels exhibit different morphologies and average lamella thicknesses. Microstructural analysis showed that the sPS/CHCl3 copolymers contain larger fractions of sssss pentad and a greater degree of blockiness. The sPS/CHCl3 copolymers contain larger phase domains, supporting that these copolymers contain longer distinct segments of pure sPS and randomly brominated sPS in a multiblock-like microstructure. In addition, the sPS/CHCl3 copolymers are more crystallizable during conditions of rapid cooling and crystallize faster at low supercooling relative to their sPS/CCl4 analogs. Simulated average chains of the Blocky copolymers, generated from the empirical pentad sequence distributions, provide strong evidence that the runs of pure sPS in the Blocky copolymers originate from the crystalline stems within the crystalline lamellae. Thus, the simulations support that semicrystalline blocky brominated copolymers with tailored chain sequences, phase behavior, and crystallization properties and can be prepared simply by changing the gelation solvent. / Doctor of Philosophy / Block copolymers are a class of large molecules (polymers) that are made up of two or more chains (blocks) of different smaller units (monomers) linked together at one of each of the chain ends. When the monomers that make up each block have distinctly different chemical properties, the blocks may be capable of self-assembling into well-ordered physical structures, which give the block copolymer unique material properties that are different, and often better than the properties of the individual blocks alone (homopolymers). Block cop olymers have thus received tremendous attention with respect to controlled preparation, tailored structure development, and customized physical properties, for their potential use in self-assembled, nanostructured materials. Nevertheless, the generally difficult procedures and conditions required to make (polymerize) block copolymers with controlled sequences limits the scope of their commercial application. As an alternative to conventional polymerization methods, this dissertation demonstrates a comparatively simple physical method to make copolymers that contain significantly non-random (blocky) monomer sequences, starting with a homopolymer and using a reagent to modify units along the polymer chain. This post-polymerization method is conducted in the homopolymer’s gel state, in which segments of the homopolymer chains are effectively shielded from the reagent. The homopolymer, syndiotactic polystyrene (sPS), was used as a model to conduct a fundamentical investigation into the effects of the polymer reaction state, i.e., gel, solution, or powder, and the gel structure (morphology) on the copolymer structure and properties. The gel-state was found to produce copolymers with a high degree of modification and a greater degree of blockiness than the solution-state and powder-state. Copolymers prepared from the gel state exhibited properties that are characteristic of conventional block copolymers. Furthermore, using the gel-state method, blocky copolymers with tailored chain sequences and properties were prepared by simply changing the gel morphology. Thus, reaction in the gel-state is demonstrated as a simple physical approach to polymer design and synthesis that will be useful in the development of next-generation functionalized materials through the modification of lowcost commodity polymers. As an advancement to the manner in which nanostructured materials are created, these tailored materials will greatly enhance the convenience of block copolymers for a wide variety of applications including structural and biomechanical materials, and polymeric membranes for energy conversion and water purification systems.

The large amount of non-degradable plastic waste has become a significant environmental concern, leading to an increased need for degradable plastics. Here in, to create degradable polymers, polyesters were produced through radical ring opening polymerization using cyclic ketene acetals. The cyclic ketene acetal monomer 5,6-benzo-2-methylene-1,3-dioxepane has been prepared for the synthesis of homo- and copolymers with methyl methacrylate, α-methylene-γ-valerolactone, α-methylene-γ-butyrolactone, cholesterol methacrylate and limonene acrylate. The polymerization was conducted using radical ring opening polymerization both in bulk and solution polymerization. The structural characteristics of the polymer were determined by different characterization methodologies, including TGA, DSC, SEC, FTIR and 1D 1H-NMR. The results obtained from 1H-NMR analysis showed the composition of the copolymers. TGA analysis revealed the thermal stability of the polymers and their degradation patterns. DSC analysis provided information about the glass transition temperatures (Tg’s) of the polymers. Moreover, the Tg indicated the presence and amounts of comonomers in the copolymers. Overall, the results showed the influence of different comonomers on the properties of the polymers by successfully incorporating the comonomers in the polymer. The thermal properties for polymers containing methyl methacrylate became more thermally stable. The Tg, analyzed with DSC, shifted from the Tg of homopolymers indicating the incorporation of both monomers. The polymers were successfully degraded via hydrolysis in alkaline conditions breaking them down into smaller pieces making them easier to recycle. To conclude, the results all indicate that the incorporation of BMDO and thereby possibly other CKA-monomers into the polymer chains of commonly used plastics could provide valuable tools in the recycling of said plastics.