Anionic Polymerization of 1,3,5-Tris(trifluoropropylmethyl)cyclotrisiloxane (F3) in Miniemulsion

Optimization and Characterization of the F-LSR Manufacturing Process Using Quaternary Ammonium Silanolate as an Initiator for Synthesizing Fluorosilicone

Due to the growing demand for versatile hybrid materials that can withstand harsh conditions (below -40 °C), fluorosilicone copolymers are becoming promising materials that can overcome the limited operating temperature of conventional rubber. In order to synthesize a fluorosilicone copolymer, a potent initiator capable of simultaneously initiating various siloxane monomers in anionic ring-opening polymerization (AROP) is required. In this study, tetramethyl ammonium silanolate (TMAS), a quaternary ammonium (QA) anion, was employed as an initiator for AROP, thereby fluoro-methyl-vinyl-silicone (FVMQ) and fluoro-hydrido-methyl-silicone (FHMQ) were successfully synthesized under optimized conditions. FT-IR, NMR, and GPC analyses confirmed that the chain length and functional group content of FVMQ and FHMQ are controlled by changing the ratio of the components. Moreover, fluorine-involved liquid silicone rubber (F-LSR) was prepared with FVMQ as the main chain and FHMQ as a crosslinker. The tensile strength, elongation, and hardness of each F-LSR sample were measured. Finally, it was confirmed through TGA, DSC, TR-test, and embrittlement testing that elastic retention at low temperatures improved even though the heat resistance slightly decreased as the trifluoropropyl group increased in F-LSR. We anticipate that the optimization of fluorosilicone synthesis initiated by QA and the comprehensive characterization of F-LSRs with different fluorine content and chain lengths will be pivotal to academia and industry.

Cationic Polymerization of Hexamethylcyclotrisiloxane in Excess Water

Ring-opening ionic polymerization of cyclosiloxanes in dispersed media has long been discovered, and is nowadays both fundamentally studied and practically used. In this short communication, we show some preliminary results on the cationic ring-opening polymerization of hexamethylcyclotrisiloxane (D₃), a crystalline strained cycle, in water. Depending on the catalyst or/and surfactants used, polymers of various molar masses are prepared in a straightforward way. Emphasis is given here on experiments conducted with tris(pentafluorophenyl)borane (BCF), where high-molar polymers were generated at room temperature. In surfactant-free conditions, µm-sized droplets are stabilized by silanol end-groups of thus generated amphiphilic polymers, the latter of which precipitate in the course of reaction through chain extension. Introducing various surfactants in the recipe allows generating smaller emulsions in size with close polymerization ability, but better final colloidal stability, at the expense of low small cycles’ content. A tentative mechanism is finally proposed.

Multisegmented polymers via step-growth and RAFT miniemulsion polymerization

We report a method to efficiently prepare multisegmented polymers via a combination of step-growth (SG) and reversible addition-fragmentation chain transfer (RAFT) polymerization.

Anionic Polymerization of Methylene Malonate for High-Performance Coatings

Here, we demonstrate the anionic polymerization and the high reactivity of the novel monomer diethyl methylene malonate (DEMM). At room temperature and under atmospheric conditions, water and anionic functional groups (i.e., carboxyl, boronic, and phenol) quickly initiate DEMM. The polymerization of DEMM in water and the final molecular weight of the polymer were both demonstrated to be pH-dependent. Systematically, investigations were conducted to study the conversion rate of DEMM with various functional groups, and the polymerization was verified to occur with anionic groups using a carboxylate-initiated DEMM system. For coating applications, we also investigated a multifunctional derivative monomer called (DEMM)₆ that is an oligomeric polyester of DEMM esterified with butanediol that contains on average six repeat units of reactive DEMM (commercially known as Forza B3000 XP). The incorporation of 15 wt % (DEMM)₆ into latex containing methacrylate acid as a functional monomer yielded cross-linked coatings with a gel content of 76.25 wt % that had a 289% improvement in rub-resistance performance compared to controls (without (DEMM)₆). This study provides a facile methodology to synthesize cross-linked latex coatings at room temperature.

Controlled synthesis and characterization of poly[methyl(3,3,3-trifluoropropyl)siloxane] with selective end groups

Controlled polymerization method to synthesize poly[methyl(3,3,3-trifluoropropyl)siloxane] with narrow molar mass distribution, broad “termination window”, selective end groups and quantitative transformation.

Miniemulsion polymerization as a versatile tool for the synthesis of functionalized polymers

The miniemulsion technique is a particular case in the family of heterophase polymerizations, which allows the formation of functionalized polymers by polymerization or modification of polymers in stable nanodroplets. We present here an overview of the different polymer syntheses within the miniemulsion droplets as reported in the literature, and of the current trends in the field.