| Heterogeneous polymerizations are widely used synthesis methods which possess great development potential. Employing these polymerization methods, a large number of materials with special structures, unusual morphologies and particular properties can be prepared. In series of heterogeneous polymerizations, phase transformation, polymerization kinetics (involving reaction rate, variation of molecule weight, and its distribution) and transfer process (heat and mass transfer) are all considered together to design and control the structure and morphology of products. Because heterogeneous polymerizations are valuable in both application development and theory research, they have a good perspect in polymer science and engineering. In another hand, fluorenyl pinacol (9,9’-bifluorene-9,9’-diol), as a potential C-C type initiator, can dissociate into ketyls (semi-pincaol radical). Because of the similar structure with xanthenyl pinacol (9,9’-bixanthene-9,9’-diol) which have been used to initiate controlled polymerization, deepen research on the performance and initiate process has great value.In this paper, based on the traditional heterogenous polymerization methods, we reported developed (self-stable) precipitation polymerization to fabricate polymeric nanoparticles (PNPs), novel Pickering Polymerization stabilized by organic functional nanoparticles, and some soap-free emulsion polymerization with ultrasonic emulsification assistanc. The new features of these developing heterogeneous polymerizations were investigated. In the field of radical polymerization initiated by BFDOL, we found the different mechanism from xanthenyl pinacol and explained the major process in the system.The major results are as follows:1. The reaction system of (self-stable) precipitation polymerization was consisted of DVB and MAH used as functional comonomers, AIBN used as initiator and low-toxic organics used as solvents. The poly (divinylbenzene-co-maleic anhydride)(PDM) micro-scale particles were prepared without any disturbing. The products morphologies were associated tightly with properties of solvents, especially with polarity and solubility parameter. With changing of the composition of solvants, the PDM particles could be with the morphology of microspheric, popcorn-like, and amorphous. The investigation also pointed out that the concentration of monomer and initiator was another factor to control the particle size in the range of500-900 nm.Subsequently,(self-stable) precipitation polymerization method was first used to prepare reactive poly (divinylbenzene-alt-maleic anhydride) nanoparticles (PDMNPs) in low-toxic n-butyl acetate. Convinient operation for PDMNPs separation was then investigated in detail. From the characterization results, the particle size was30nm with a few pendant C=C bonds (0.84mmol/g polymer) and lots of anhydride groups. The particle was confirmed as highly crosslinked nanoparticles ant the Tg and Ts was204and250℃, respectively.Then, in a small range of filling amounts, exploratory evaluation on application of the particles being attempted to enhance transparent rubber was carried in the system of DCP, naphthenic oil, PDMNPs and SSBR2305. After the sequent process of mixing, staying, and vulcanization (at165℃,20min), the good transparent performance was maintained and the strength properties was enhanced a little.2. Responsed to the progress of green chemistry, and satisfied with new demands of polymer-particle materials properties, this dissertation developed two novel kinds of Pickering polymerization stabilized with organic polymeric nanoparticles, based on the research of PDMNPs. Surface properties PDMNPs study showed that these nanoparticles can be used as an oil-in-water Pickering stabilizer. Two kinds of Pickering polymerization were mainly different in: One of them using APS initiation and the formation of emulsion was during the polymerization while the other initiated by AIBN and must be assited with ultrasound emulsification at the beginning of polymerization. The reaction recipes (NPs, ammonia, salt effection, and etc) were studied in Pickering polymerization of styrene. The study showed that PDMNPs could play an efficient stabilizer in Pickering polymerization and the detailed results as follows:In APS system, the raspberry-like morphology was likely to be formed through PDMNPs (pendant double bonds) chemically anchored on the PS microspheres’surface, and with increasing of PDMNPs amounts, the pimples size and shape changed regularly. The kinetics of polymerization indicated that this kind of Pickering polymerization was similar to conversional emulsion polymerization.In AIBN system, the investigation pointed out that this kind of Pickering polymerization could fabricate the narrow-distributed PS microspheres with non surfactant residue. The difference from APS system was indicated that amonilyzed PDMNPs, in AIBN initiation system, play the role of immobilizer not as good as them did in APS one. This method which might be used to prepare monodispersed polymeric microsphere was confirmed in other monomers.3. Inspired from the research on Pickering polymerization, a novel potential green strategy to fabricate mono-dispersed PS microspheres through surfactant-free emulsion polymerization with ultrasonic emulsification provided by common ultrasonic cleaner, was preliminarily explored. The study focused on the cleaner parameters (mainly output power and frequency), composition of polymerization system and technique conditions duing thermal polymerization. And the PS microspheres could be obtained at the following conditions:ratio of oil to water was3:40;3min ultrasonic emulsification in any type of cleaners; and200rad/min mechanical agitation under75. The explaination of polymer chain and cavitation assisted to stabilize the system was used to describe the plausible mechanism. The starting point of this novel heterogeneous polymerization supplied a new idea to prepared the polymer particles.4. For completing one of our group researches, novel controlled/living radical polymerization system, we lead an investigation on the basical structure of fluorenone, which could be prepared into BFDOL through using Zn-ZnCl2red-coupling method in the tetrahydrofuran aqueous solution. The best reaction temperature was estimated at30℃and yield reached81.5%. The synthesized compound was then used as an initiator to initiate methyl methacrylate (MMA) solution polymerization found that BFDOL can initiate polymerization in tetrahydrofuran, toluene and anisole; temperature effected on the polymerization rate and the molecular weight which was in accordance with characteristics of the conditional radical polymerization; while once tetrahydrofuran was solvent, BFDOL could initiate polymerization reaction of MMA under relatively low temperature. 5. Using2,2,6,6-tetramethyl-1-piperidinyl free radical (TEMPO) to capture active radical in the decomposition process of BFDOL and initiation process. Liquid chromatography-mass spectrometry analysis was employed to separate and examine the capturing product; NMR techniques were used to confirm the structure of the capturing products; as well, the refractive index differential-UV absorption dual detector technology GPC was used to track reaction kinetics. In the end, BFDOL was confirmed as a kind of hydrogen transfer radical polymerization initiator. The pathway of β-fracture mechanism was proposed to explain the transfer process. The different effect on initiation with xanthenyl pinacol was attributed to the difference in cyclo structure. |
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