Xiaobo Deng

Preparation and Characterization of PDMS-PMMA Interpenetrating Polymer Networks with Indistinct Phase Separation

This paper describes the preparation and characterization of the interpenetrating polymer networks (IPNs) of polydimethylsiloxane-polymethyl methacrylate (PDMS-PMMA) via 3-(methacryloxypropyl)-trimethoxy-silane (MPS) as the crosslinking agent. The structure of synthesized IPNs was characterized by 1HNMR, DSC, FT-IR, XPS, SEM and AFM, respectively. The experimental results show that, with the method adopted in this preparation process, the phase separation between PDMS and PMMA in PDMS-PMMA IPNs has been reduced to a smaller extent than other previous reports.

A Self-Switchable Polymer Reactor for Controlled Catalytic Chemistry Processes with a Hyperbranched Structure

A self-switchable polymer reactor with a hyperbranched structure for controlled catalytic chemistry processes is reported. This polymer reactor was made of silver nanoparticles and a polymer carrier consisting of hyperbranched polyethylenimine and hydroxyethyl acrylate that behaved as thermally switchable domains. Below the transfer temperature, relatively strong catalytic reactivity was demonstrated due to the leading role of hydrophilic groups in the switchable domains, which opened access to the substrate for the packaged silver nanoparticles. In contrast, it showed weak catalysis at relatively high temperatures, reducing from the significantly increased hydrophobicity in the switchable domains. In this way, the polymer reactor displays controllable, tunable, catalytic activity based on this approach. This novel design opens up the opportunity to develop intelligent polymer reactors for controlled catalytic processes.

Preparation and surface properties of siloxane-acrylate copolymer with high siloxane content

A copolymer of acrylate and 3-(methacryloxypropyl)-trimethoxysilane (MPS) with high MPS content was prepared by emulsion copolymerisation and characterised by FT-IR, surface tension analysis and the static contact angle method. After Soxhlet extraction, there was scarcely any monomer or homopolymer left in the solvent and the weight losses in all the samples appeared to be negligible, which indicated that almost all the MPS and acrylate monomers had been copolymerised in the reaction. The FT-IR results also supported the same conclusion because there was no C=C peak in the spectrum. The surface tension also was investigated, and the outcome showed that the surface tension decreased with increasing MPS content in the copolymer. The surface properties of the copolymer films were studied by the static contact angle method too. Compared with the acrylate homopolymer, the copolymer containing MPS was more effective in creating a hydrophobic surface and the introduction of MPS was capable of making an obvious increase in water repellency. All the measurements were consistent with the conclusion that a copolymer of siloxane and acrylate with a high siloxane content has been prepared successfully. The siloxane content reached 30%, which was much higher than other reported values.

Preparation and Characterization of Core-Shell Latex Containing PDMS in the Shell

Abstract In this paper, the composite latex particles with a polyacrylate (PA) core and a polydimethylsiloxane (PDMS) shell via 3-(methacryloxypropyl)- trimethoxy silane (MPS) as the medium to link the core and shell were prepared by semicontinuous seeded emulsion polymerization and were characterized by transmission electron microscopy (TEM), FT-IR, particle size analyzer and X-ray photoelectron spectroscopy (XPS). The TEM images indicated that the particles containing organic siloxane (D-40) displayed an evident core/shell structure. Additionally, the study by FT-IR and XPS also revealed that D4 could be grafted onto the surface of polyacrylate core because there appeared the characteristic peaks of Si-O-Si group and Si 2s and Si 2p in the spectra of FT-IR and XPS respectively. Besides, the atomic ratio of C/Si on the surface of the core/shell particles (D-40) was close to the ratio of C/Si in the latex of pure PDMS that could prove the PA particles were fully covered by PDMS and the properties of PDMS should be embodied in a maximal level. In order to testify the result, the surface properties of the films produced from the core/shell particles were also investigated by the static contact angle method. Compared with the copolymer of PA, the core/shell particles were more effective to create hydrophobic surface, so, the introduction of D4 was capable of obvious increase in water repellency.

Thermodynamic and Kinetic Considerations - Effect of Organic Siloxane on MMA Polymerization

The effects of 3-(methacryloxypropyl)-trimethoxysilane (MATS) and vinyl trimethoxysilane (VTMOS) on methyl methacrylate (MMA) polymerization have been investigated. The two co-monomers appear to show opposite effects. The polymerization shows a higher rate of polymerization and extent of conversion in the presence of MATS than in its absence. However, a lower rate of polymerization and extent of conversion are obtained in the presence of VTMOS. The difference can be related to the different roles of the co-monomers. The increase in the rate of polymerization and conversion with MATS can be attributed to the higher reactivity of monomers. The lower conversion with VTMOS may be due to the electronic effects associated with VTMOS, which can decrease the electric density of the active double bond in MMA and therefore deactivate the polymerization. Further investigation shows that the change of free energy in the polymerization with MATS is lower than without MATS. Also, monomer reactivity in the presence of MATS is higher than in the absence of MATS. The decrease in free energy may be a thermodynamic response to the increase in the conversion. The increase in monomer reactivity may be responsible for increasing the rate of polymerization.

The preparation of core/shell particles with siloxane in the shell

Core-shell microspheres ranging in average diameter from 12.829 to 15.039 μm, with a poly butyl methacrylate (BMA) core, and a poly 3-(methacryloxypropyl)-trimethoxysilane (MATS) shell, were prepared with methanol as the dispersion medium, by a successive seeding method under kinetically controlled conditions. To date, although some of particles (PSi/PA) have been prepared by seeded emulsion polymerisation, only a few core/shell (PA/PSi) microspheres have been reported the literatures. To prepare core/shell (PA/PSi), the core was first synthesized by dispersion polymerisation and to form seeds; addition of MATS monomer was started after 90~95% conversion of the BMA. The reaction was prolonged for another 12 h to achieve complete consumption of MATS monomer. Microspheres; containing hydrophilic PBMA as the core and hydrophobic PMATS as the shell, were successfully formed through the free radical of surface in the core. The particles morphology and size distribution were examined using a Transmission electron microscope and a Malvern Master Sizer/E particle size analyser, respectively.