One‐step synthesis of polymer dispersions with large narrow‐size‐distribution particles via heterophase polymerization in the presence of surface‐active water‐insoluble organosilicon macromers

Abstract

Polymerizable water-insoluble surface-active macromers (SAMs), namely ⊍,ω-divinylpolydimethylsiloxane (DVPDMS), ⊍,ω-dipropylmethacrylatepolydimethylsiloxane (DPMPDMS) and ⊍,ω-pair(vinylbenzyl)polydimethylsiloxane (PVBPDMS), were synthesized and characterized using NMR. The colloidal-chemical properties of the synthesized compounds were studied in comparison with non-polymerizable polydimethylsiloxane. Using DVPDMS, DPMPDMS and PVBPDMS as copolymerizable emulsifiers, polystyrene and poly(methyl methacrylate) suspensions with large particles, narrow particle size distribution and with the absence of the residual surfactant in the waste water were obtained. It is shown that in the presence of DPMPDMS it is possible to obtain polymer suspensions with an average particle diameter of 1.6 ∼m. The proposed mechanism of the effects of the SAMs on the polymerization is based on the copolymerization with the main monomers in the monomer-polymer particle interphases which results in stabilization of the particle protective layers from early stages of the reaction.

Effect of Molecular Architecture of Surface-Active Organosilicon Macromers on Their Colloidal Properties in Relation to Heterophasic Radical Polymerization of Styrene and Methyl Methacrylate

“…All syntheses were carried out in an argon atmosphere. Synthesis of α,ω-dipropylmethacrylatepolydimethylsiloxane with the number of repeating siloxane units n = 20 (l-SAM) Synthesis of α,ω-dipropylmethacrylatepolydimethylsiloxane with the number of repeating siloxane units n = 20 (l-SAM) was carried out according to the procedure given in [40]. The reaction scheme, synthesis procedure and 1 H NMR spectrum are given in Supplementary Materials (Figure S1).…”

“…This structure of the adsorption layers can probably explain the relatively small differences in the colloidal-chemical characteristics of these SAMs as well as the similarity of the colloidal-chemical characteristics as compared to some other water-insoluble oligomers (dimeric, comb-type, etc.) [40,53]. The polymerization was carried out under the following conditions: the monomer/water volume ratio was 1/9, respectively; the concentration of potassium persulfate (PSP) used as initiator was 1 wt.% per monomer; the temperature was 80 ± 0.5 • C; and the SAM concentration was varied from 1 to 1.5 wt.% per monomer, which corresponds to the concentration of saturated interfacial layer in the studied toluene-water model system.…”

“…The conversion-time curves of kinetics of polymerization of styrene and methyl methacrylate in presence of SAMs are shown in Figure 3a It can be seen that the kinetic curves are S-shaped, which is typical for heterophase radical polymerization of styrene and methyl methacrylate. The initial section of the kinetic curves is characterized by a low reaction rate and, according to the literature, is called the induction period [10,40,49]. Then, the rate of polymerization grows and changes to It can be seen that the kinetic curves are S-shaped, which is typical for heterophase radical polymerization of styrene and methyl methacrylate.…”

“…In refs [40,41], it was shown that the use of water-insoluble oligomeric surfactants of various chemical structures (hydrocarbon and organosilicon) enables to synthesize such dispersions via one-step heterophase radical polymerization. The mechanism of the effect was based on the assumption that the surface-active oligomers being incompatible with the forming polymer are pushed onto the interface of the monomer droplet with water and build their "thick" and strong adsorption layer, which provides stability of the system in the whole course of polymerization.…”

Special Issue: Functional Polymers and Composites: From Synthesis to Applications (Dedicated to the 80th Anniversary of Professor George S. Georgiev)

“…The work by Chernikova and coworkers 21 describes the application of addition‐fragmentation chain transfer (RAFT) copolymerization of acrylonitrile with various acrylates leading to materials suitable for the preparation of carbon fibers. The article that follows, by Zubov and collaborators, 22 deals with the preparation of dispersions with narrow particle size distributions by the radical copolymerization of silicon‐containing monomers. The following 4 papers are dedicated to materials (synthetic or natural polymer‐based) with potential biomedical applications.…”