SOAPLESS EMULSION COPOLYMERIZATION IN THE PRESENCE OF BARIUM SULFATE POWDER

To investigate soapless emulsion copolymerization in the presence of a solid phase, copolymerization experiments were carried out for the styrene-butyl acrylate-K_2S_2O_8-water system by using barium sulfate powder,which is assumed to be chemically inert.Reaction conditions were varied with respect to barium sulfate powder quantity,initiator concen- tration and temperature.These factors were investigated with respect to the effect on reaction rate and conversion,polymer particle number and diameter,and latex stability.

Semibatch Emulsifier-free Emulsion Copolymerization of Methyl Methacrylate and n-Butyl Acrylate in the Presence of 2-Hydroxyethyl Methacrylate

The semibatch emulsifier-free emulsion copolymerization of methyl methacrylate (MMA) and n-butyl acrylate (BA) in the presence of 2-hydroxyethyl methacrylate (HEMA) initiated by K2S2O8 (PSP) was studied. The average particle diameter increases with an increase of total solids content, HEMA content, PSP content, ionic strength of the system and monomer feed rate, and decreases with the monomer feed ratio from 3/1 (MMA/BA mole.) to 1/3. The stability of this reaction system is improved by adding HEMA as nonionic comonomer. The high solids content (50%) latex with monodisperse particle can be obtained using this process.

EFFECT OF 2-HYDROXYETHYL METHACRYLATEON SEMIBATCH EMULSIFIER-FREE EMULSION COPOLYMERIZATION OF METHYLMETHACRYLATE AND BUTYL ACRYLATE

The semibatch emulsifier-free emulsion copolymerization of methyl methacrylate(MMA and butyl acrylate (BA) in the presence of 2-hydroxyethyl methacrylate (HEMA)initiated by K2S2O8 (PSP) was studied. The latex particles can maintain an appreciablestability during the emulsifier-free emulsion copolymerization of MMA and BA in thepresence of HEMA The average particle diameter increase with an increase of totalsolids content, HEMA content, PSP content, ioniC strength of the system and monomerfeed rate, and decrease with the monomer feed ratio From 3/1(MMA/BA;molar ratio.)to1/3. The stability of this reaction system is improved by adding HEMA as nonioniccomonomer High solids content (50%) latex with monodisperse particle can beobtained using this process.

One-step synthesis of self-healable hydrogels by the spontaneous phase separation of linear multi-block copolymers during the emulsion copolymerization

Self-healable polyacrylamide-based hydrogels were prepared at room temperature via a one-step emulsion copolymerization of acrylamide（AM）,dodecyl 2-methacryIate（DM）,and 5-acetylaminopentyl acrylate（AAPA） using sodium dodecyl sulfonate（SDS） as the emulsifier and ammonium persulfate（APS）as the initiator.The produced linear multi-block copolymer chains are composed of randomly-linked hydrophilic polyacrylamide segments（PAM） and hydrophobic segments constituted by DM and AAPA units（P（DM-co-AAPA））.The P（DM-co-AAPA） segments will self-aggregate into hydrophobic microdomains during the polymerization process driven by the hydrophobic interactions,and finally separate from water phase,acting as the crosslinks and leading to the formation of strong hydrogels with a storage modulus as high as 400 Pa.These hydrophobic microdomains will be dissolved in water when the temperature increases to 70℃,resulting in a temperature-responsive reversible sol-gel transition of the prepared hydrogels.Furthermore,the prepared hydrogels have excellent self-healing ability.The broken hydrogels can be automatically healed into a body with a same strength within 2-min＇s contact.This work provides a new simple way to prepare reversible physical crosslinked hydrogel with high strength and self-healing efficiency.

Synthesis of submicron-sized composite particles with unique morphology by emulsifier-free seeded emulsion copolymerization

Polystyrene （PSt） microspheres with diameter of 375 nm to be used as the seeds for seeded emulsion polymerization were prepared via emulsion polymerization using potassium persulfate （KPS） as initiator in ethanol-water mixed solvents. Emulsifier-free seeded emulsion copolymerization of styrene （St） with acrylonitrile （AN） was carried out in the presence of poly（ethylene glycol） monomethoxymonomethacrylate （PEGm） macromonomer as reactive stabilizer and 2,2＇-azobisisobutyronitrile （AIBN） as initiator to obtain submicron-sized PEGm graft poly（styrene-coacrylonitrile） （PEGm-g-PSAN） composite particles with unique morphology. Scanning electron microscopy （SEM） indicated that St and AN together contributed to forming the unusual morphology. The concentration of St and AN, total monomer concentration, initiator type and the monomer adding method remarkably affected the morphology of the composite polymer particles.

Study on N-Phenylmaleimide/Styrene /Acrylonitrile Copolymer Prepared by Emulsion Polymerization

The emulsion polymerization of N-phenylmaleimide, Styrene and acrylonitrile was studied. The thermal property of this copolymer was measures by dynamic thermomechanical analysis(DMA). The mechanical properties, such as tensile strength, hardness and fie-cural Strength were StUdied experimentally. The results indicated that not only the monomer component but also the polymerization technologies have effect on the properties of the copolymer. The optimum monomer content and suitable polymerization method were obtained.

Ether-/Ester-/Fluorine-Rich Binding Emulsion Formula for Lithium-Ion Batteries

Practical application of a Si anode in a high-energy-density battery cannot be achieved due to the huge volume expansion of these anodes.Researchers have focused on binders of the anode to restrict volume expansion in order to address this issue,as the hydrogen bonds and mechanical properties of binders can be used to enhance adhesion and accommodate the volume changes of a Si anode.Herein,we comprehensively consider binders’hydrogen bonds,mechanical properties,stability,and compatibility with the electrolyte solution,and design an ether-/ester-/fluorine-rich composite polymer,named P(TFEMAco-IBVE).The proposed binder formula possesses outstanding stability,adhesion,and mechanical strength;moreover,it can accommodate the dramatic volume changes of a Si electrode and exhibits excellent electrochemical performance,achieving a high areal capacity of about 5.4 mA·h·cm^(-2).This novel polymer design may be applied to other electrode materials in the next generation of lithium-ion batteries.

Effect of stirring on preparation of hollow copolymer particles by alkali/cooling method

Hollow particles were prepared by the treatment of styrene-metbacrylic acid copolymer particles with alkali/cooling method. The influences of stirring position （in aqueous phase or at the interface of O/W） and stirring speed （90, 110 and 240 r/min） on the formation of hollow particles were investigated. It is found that the soft stirring in aqueous phase at 90 r/min leads to the formation of monohollow particles, while the violent stirring at the interface of O/W and 240 r/min gives non-hollow products. In contrast, the weak stirring in aqueous phase at 110 r/min results in sterically heterogeneous dispersion of methacrylic acid-rich regions within the original particles, and hence the formation of multihollow particles. Further investigation indicates that the change of stirring efficiency provides a way to tune the diffusion behavior of monomer styrene, and therefore influences the distribution of methacrylic acid units in the original particles as well as the morphology of the treated particles.

EFFECTS OF ω-ACRYLOYL POLY (ETHYLENE OXIDE) MACROMONOMER ON EMULSIFIER-FREE EMULSI0N COPOLYMERIZATION OF METHYL METHACRYLATE AND n-BUTYL ACRYLATE

Well-defined nonionic hydrophilic ω-acryloyl poly(ethylene oxide) macro-monomer (PEO-A) has been prepared by living anionic polymerization of ethylene oxidewith diphenyl methyl potassium as the initiator and acryloyl chloride as the reaction termi-nating agent. The polymer was characterized by FTIR and SEC. The emulsifier-free emul-sion polymerization of methyl methacrylate (MMA) and n-butyl acrylate (BA) containingvarious concentrations of PEO-A was studied. In all cases stable emulsion coplymerizationsof MMA and BA were obtained. The stabilizing effect was found to be dependent on themolecular weight and the feed amount of the macromonomer.

Preparation of MMA-BA-DMAEMA Nanosized Latex

The terpolymer latex of methyl methacrylate (MMA)/butyl acrylate (BA)/ dimethyl aminoethyl methacrylate (DMAEMA) with diameter of less than 100 nm was prepared by seeding semi-continuous emulsion copolymerization using APS (ammonium persulfate) / TMEDA (N,N,N, N-tetramethylethylenediamine) as the redox initiators and SDS (sodium dodecylsulfate) and OP (P-octylpolyethylene glycol phenylether) as co-emulsifiers. The factors that influenced the process stability of the copolymerization and the particle size of the latex were investigated. The addition of aqueous ammonia as coagulation inhibitor provided better process stability of the copoly- merization. The addition of acetic acid as the acidification agent caused a remarkable reduction of the latex particle size.