KINETICS OF SUSPENDED EMULSION POLYMERIZATION OF METHYL METHACRYLATE*

 The kinetics of suspended emulsion polymerization of methyl methacrylate (MMA), in which water acted as the dispersed phase and the mixture of MMA and cyclohexane as the continuous phase, was investigated. It showed that the initial polymerization rate (R_p0) and steady-state polymerization rate (R_p) were proportional to the mass ratio between water and oil phase, and increased as the polymerization temperature, the potassium persulphate concentration ([I]) and the Tween20 emulsifier concentration ([S]) increased. The relationships between the polymerization rate and [I] and [S] were obtained as follows: R_p0∝[I]^0.71[S]^0.23.The above exponents were close to those obtained from normal MMA emulsion polymerization. It also showed that the average molecular weight of the resulting poly(methylmethacrylate) decreased as the polymerization temperature,[I]and [S] increased. Thus, MMA suspended emulsion polymerization could be considered as a combination of many miniature emulsion polymerizations proceeding in water drops and obeyed the classical kinetics of MMA emulsion polymerization.     

SUSPENSION-SWELLING GRAFT COPOLYMERIZATION——SYNTHESIS OF ACS RESINS*

Acrylonitrile (AN)-chlorinated polyethylene (CPE)-styrene (St) (ACS) terpolymer was synthesized by suspension-swelling graft copolymerization method, in which two key factors such as dispersing system and time were studied. Highly effective comples dispersing system was chosen and determined, and two-layer protection model was put forward to clarify the stable effect mechanism Varying the swelling time of CPE in AN and St monomer mixture, some results such as grafting effect, particle characteristics, rubber particle morphology and its size distribution, and properties of ACS resins were investigated , thus the optimum swelling time was proposed.     

STUDIES ON THE OXIDATION AND GRAFT COPOLYMERIZATION OF POLYETHERS

Polyethers could form hydroperoxide under air-oxidation or photo-oxidation in the presence of H_2O_2. The scission of ether linkage induced by moderate oxidation was prevented by controlling the reaction time and hydroperoxide concentration. The oxidation rate was affected by the end groups of polyethers. The decreasing order of oxidation rate for various poly(tetramethylene ether) glycol derivatives having different end groups are as follows: poly(tetramethylene ether) glycol (PTMG)>poly(tetramethylene ether)acetate (PTMGAC) >poly(tetramethylene ether) phenyl carbamate (PTMGPC). The urethane end groups in PTMGPC increase the resistance toward oxidation. Polyether hydroperoxide reacts with ferrous ion or N,N-dimethyl toluidine (DMT) to form polymericoxy radical which then initiates the graft copolymerization of vinyl monomers at low temperature, and was devoid of homopolymerization. The copolymer after separation and purification was proved to be a graft one by IR analysis and elemental analysis.     

SURFACE MODIFICATION OF MICROPOROUS POLYPROPYLENE MEMBRANES BY GRAFT POLYMERIZATION OF N,N-DIMETHYLAMINOETHYL METHACRYLATE

Surface modification of microporous polypropylene hollow fiber membranes was performed by radical-induced graft polymerization of N,N-dimethylaminoethyl methacrylate (DMAEMA). The influences of temperature, monomer concentration and pre-adsorbed amount of benzoyl peroxide on grafting degree were studied respectively. It was found that the appropriate graft temperature was 75℃, at which the grafting degree was the highest and the hydrolytic decomposition of DMAEMA the lowest. Scanning electron photomicrography and the average pore diameters of the modified membranes demonstrated that part of the micropores on the membrane surface was plugged by the grafted polyDMAEMA chains, especially at high grafting degree. Contact angle and water swelling experiments showed that a moderate grafting degree could improve the hydrophilicity of the membranes. In the range of I 1.3%o-12.0% grafting degree, the water swelling percentage reached its maximum (51.1%) and the contact angle reached its minimum (74 degrees). The bovine serum albumin (BSA) adsorption experiment indicated that the grafted polyDMAEMA had a dual effect on protein adsorption. At the first stage, the BSA adsorption decreased with increasing of DMAEMA grafting degree. As the interaction between BSA and polyDMAEMA on membrane surface increased, the BSA adsorption increased with increasing of DMAEMA grafting degree.     

POLYMERIZATION OF METHYL METHACRYLATE WITH ORGANOLANTHANIDES AS SINGLE-COMPONENT CATALYSTS*

 It was first found that Ind₂Y(μ-Et)₂AlEt₂ and Ind₂LnN(i-Pr)₂ (Ln = Y, Yb) exhibit extremely high catalytic activity in the polymerization of methyl methacrylate. The reactions can be carried out over a quite broad range of polymerization temperatures from -30 to 50℃. PMMA with high molecular weight (7.8 × l0^-5) and high isotacticity (94%) can be obtained by using Ind₂Y(μ-Et)₂AlEt₂, and narrow molecular weight distribution (M_w/M_n < 1.5) can be obtained by using Ind₂LnN(iPr)₂(Ln = Y, Yb).     

STUDIES ON THE OXIDATION AND GRAFT COPOLYMERIZATION OF POLY(ETHER-URETHANE)

A new method of graft copolymerization of acrylamide (AAM) on poly(ether-urethane) (PEU) which was prepared from poly(tetramethylene ether) glycol (PTMG), 4,4'-diphenylmethane diisocyanate (MDI) and ethylene diamine or butanediol extender was investigated. Hydroperoxide group was first introduced onto the surface of PEU through photo-oxidation in the presence of hydrogen peroxide, then it was reacted with ferrous ion or N,N-dimethyl toluidine (DMT) to initiate AAM graft copolymerization on PEU surface. The graft reaction could be carried out effectively at low temperature. The formation of graft copolymer has been verified by its water absorption % and the scanning electron microscopy photographs. Some model compounds of PEU soft segment and hard segment were synthesized in order to clarify the site of graft reaction. The results of oxida-tion and graft copolymerization of model compounds showed that this graft copolymerization possesses higher selectivity, and it takes place predominately at the polyether segments, because the ether linkage in soft segment is very sensitive to oxidation and can form hydroperoxide easily. Thus, the grafting site appears to be at α-carbon of the ether linkage.     

DESIGN AND SYNTHESIS OF NOVEL CHIRAL IONIC LIQUIDS AND THEIR APPLICATION IN FREE RADICAL POLYMERIZATION OF METHYL METHACRYLATE

Two new chiral ionic liquids, 1 -((-)-menthoxycarbonylmethylene)-3-methylimidazolium hexafluorophosphateand 1-((-)-menthoxycarbonylmethylene)-3-hexadecylimidazolium hexafluorophosphate, were designed an d prepared. Theirchemical structures were characterized by ~1H-NMR. Reverse atom transfer radical polymerization of methyl methacrylate(MMA) in these two ionic liquids was carried out using AIBN/CuCl_2/bipy as the initiating system. The resultant well-definedpolymethyl methacrylate (PMMA) was employed as a macroinitiator to induce the atom transfer radical polymerization ofmenthyl methacrylate (MnMA) in chlorobenzene, which yielded a PMMA-b-PMnMA diblock copolymer with narrow polydispersity.     

HELIX SENSE-SELECTIVE COPOLYMERIZATION OF TRIPHENYLMETHYL METHACRYLATE WITH CHIRAL ANIONIC INITIATORS

Optically active copolymers of pairs of three monomers, triphenyl (methyl methacrylate)and one or two pyridyl substituted methyl methacrylate homologues, were obtained by helix-sense-selective copolymerization using complexes of organolithium with chiral ligand as anionicinitiators in toluene at low temperature. The copolymers obtained with (-)-sparteine (Sp) and(S,S)-(+)-and (R, R)-(-)-2, 3-dimethoxy-1, 4-bis (dimethylamino) butanes((+)-and (-)-DDB) complexes of organolithium showed low optical activity, but PMP complex with N, N-diphenylethyleneamine monolithium amide (PMP-DPEDA-Li) was effective in synthesizingcopolymers of high optical rotation ([α]_D~(25) about+320～1370°)which were comparable to thoseof relative homopolymers with one-handed helical structure.     

SYNTHESIS OF γ-SUBSTITUTED-PROPYLCYCLOTETRASILOXANES AND THEIR EMULSION COPOLYMERIZATION WITH OCTAMETHYLCYCLOTETRASILOXANE*

Four γ-substituted-propylcyclotetrasiloxanes have been synthesized. Emulsion copolymerizations of these cyclosiloxanes with octamethylcyclotetrasiloxane have been carried out both in cationic and anionic emulsion systems. By way of these reactions, stable emulsions of organosilicon polymers which contain carbonfuctional groups such as γ-hydroxypropyl, γ-acetoxypropyl and γ-chloropropyi have been obtained.The effects of temperature, catalyst and the amount of γ-substituted-propylcyclotetrasiloxanes in emulsion copolymerizations have been studied.     

STUDIES ON THE POLYMERIZATION OF 2,2,6,6-TETRAMETHYL PIPERIDINYL METHACRYLATE

The radical homo-and co-polymerization of 2,2,6,6-tetramethyl piperidinyl methacrylate (TM-PM) with various initiators have been studied. It was found that, with azo-type initiators, the poly-merization proceeded readily, while with acyl peroxide initiators, the polymerization was inhibitedeffectively because of the formation of the stable TMPM-oxyl radical, identified by ESR. Thisobservation was further confirmed by the absence of inhibition effect on the addition of 2,2,6,6-tetramethyl 4-piperidinol to the polymerization system, whereas remarkable inhibition was observed onthe addition of the stable 2,2,6,6-tetramethyl 4-piperidinol N-oxyl radical. The reaction mecha-nism was discussed. We also found that when TMPM reacted with BPO in petroleum ether, N-benzoyloxy 2,2,6,6-tetramethyl 4-piperidinyl methacrylate was formed, and this novel compound has been characterizedwith IR, ESR, NMR and Mass Spectroscopy.     

THE MECHANISM OF THE COPOLYMERIZATION OF BF_3-COMPLEXED ETHYL ACRYLATE WITH PROPYLENE

The copolymerization of BF_2-omplexed ethyl acrylate with propylene in the presence ofAIBN at 25℃was investigated. It was found that the rate of the copolymerization was propor-tional to the square root of the initiator concentration. The chain transfer agent CCl_4 greatly af-fects the inherent viscosity of the resulting copolymer. The smaller the dielectric constant of thesolvent, the greater the rate of copolymerization is. The equal concentration of the two monomersgive the maximum copolymerization rate. The ~1H-NMR and ~(13)C-NMR analysis indicated, when[EA.BF_2]/[EA.BF_2]+[P]>0.5, the resulting copolymer was the acrylate-rich random copoly-mer. Through the kinetic experiments we suggest that copolymerization follows the mechanismof the random copolymerization of the ternary complex with binary complex. When [EA.BF_3]/[EA.BF_2]+[P]<0.5, the resulting copolymer is always strictly alternating, and the alternatingcopolymerization follows the mechanism of the ternary complex homopolymerization. Usingthe homolog of the propylene, 1-pentene, we found that BF_3-complexed ethyl acrylate can forma ternary complex with 1-pentene identified by UV spectroscopy. This is a strong evidence forthe mechanism of ternary complex homopolymerizetion.     

ELECTROCHEMICAL COPOLYMERIZATION OF ANILINE AND AZURE B*

The electrochemical copolymerization of aniline and N,N,N'-trimethylthionin (azure B) in aqueous solutions hasbeen carried out using the potential sweep method, The optimum conditions for the coelectrodeposition are that the pH valueand the temperature of the electrolytic solution are controlled at 5.57 and 30℃, respectively, and the scan potential range isset between - 0.25 and 1.10 V (versus SCE). The copolymerization rate of aniline and azure B is about 3 times larger thanthat of aniline in the absence of azure B. The copolymerization of aniline and azure B was verified from the results of visiblespectra during electrolysis, FTIR spectra and the atomic force microscopy (AFM) images of the polymers. The in situ visiblespectrum for the electrolysis of the solution containing aniline and azure B is different from that of the respective aniline andazure B. The FTIR spectrum of the copolymer is not a superposition of that of polyaniline and poly(azure B). The AFMimage of the copolymer is different from those of polyaniline and poly(azure B) and is not a mixture of individual polymers.The conductivity of thc copolymer synthesized at pH 5.57 is four orders of magnitude higher than that of polyanilinesynthesized under the same conditions, bat in the absence of azure B. The clectrochemical properties of the copolymer aremainly attributed to polyaniline, but the copolymer has a better electrochemical reversibility and a much faster charge transferthan those of polyaniline.     

COPOLYMERIZATION PROCESS OF TRIPHENYLMETHYL METHACRYLATE AND MMA WITH CHIRAL ANIONIC COMPLEX INITIATOR

The copolymerization process of triphenylmethyl methacrylate (TrMA) and methylmethacrylate (MMA) using chiral anionic complex initiator (-) SP-FlLi (Scheme 1) has beenstudied in toluene and THF, respectively. The copolymer obtained in toluene possessed muchhigher specific rotation than that in THF. These copolymers have shown a tendency to a random and a like alternating structure, respectively.     

Ce4＋－Ce3＋循环体系引发淀粉与丙烯酰胺接枝共聚合反应动力学研究

The cyclic initiating system of Ce⁴⁺ - Ce³⁺ - Ce⁴⁺, in which the product of reduced ion Ce³⁺ forming from Ce⁴⁺ after initation being oxidized again to the original oxidizing ion Ce⁴⁺ is examined. The characters of process of the graft copolymerisation using the cyclic initiating system is compared with the ones using ceric and persulphate individually. When using the cyclic systerm as initator, it was more effective to graft polymerise acylamide onto starch and a rather high proportion of graft copolymer was made as opposed to using persulphate individually.     

STUDIES ON RADICAL POLYMERIZATION OF METHYL METHACRYLATE INITIATED WITH ORGANIC PEROXIDE-AMINE SYSTEMS

Radical polymerization of methyl mcthacrylate (MMA) initiated with various diacyl peroxideamine systems was studied. Benzoyl peroxide (BPO) and lauroyl peroxide (LPO) were used as diacyl peroxide component, N,N-dimethyl aniline (DMA) and its para substituted derivatives, i.e., N,N-dimethyl-p-toluidine (DMT), p-hydroxymethyl-N,N-dimethyl aniline (HDMA), p-nitro-N,N-dimethyl aniline (NDMA) and p-dimethylamino benzaldehyde (DMAB) were used as amine components. It was found that the peroxide-DMT systems give higher rates of bulk polymerization R_p of MMA than the organic hydroperoxide-DMT systems with the following descending order BPO-DMT>LPO-DMT>CHP (cumene hydroperoxide)-DMT>TBH (tert-butyl hydroperoxide)-DMT. The aromatic tertiary amines possess obvious structural effect on the R_p values in the diacyl peroxideamine system. The overall activation energy of MMA polymerization was determined and thekinetics of polymerization of MMA initiated with BPO-DMT system was investigated.     

二过碘酸合银(II)氧化还原引发丙烯酸甲酯在尼龙1010上接枝共聚合反应的研究

二过碘酸合银（ＩＩ）氧化还原引发丙烯酸甲酯在尼龙１０１０上接枝共聚合反应的研究刘盈海刘卫宏赵敏孟劲功（河北大学化学系保定０７１００２）关键词二过碘酸合银（ＩＩ）钾，尼龙１０１０，氧化还原引发，丙烯酸甲酯，接枝共聚目前Ｃｅ（ＩＶ）被认为是一种十分...     

VISIBLE LIGHT PHOTOPOLYMERIZATION OF METHYL METHACRYLATE COINITIATED WITH TITANOCENE AND KETOCOUMARIN DYE*

The photosensitive system which can initiate methyl methacrylate with visible light was composedof compound 1 bis(η-5-cyclopentadienyl)-bis[2,6-difluoro-3-(1-H-pyrrolyl)phenyl]titanium (titanocene) andcompound 2 [(3,3'-carbonylbis(7-diethylamino coumarin)] (ketocoumarin dye). The high photosensitiveinitiating efficiency of this photosensitive system could be very promising for efficient system for laser (Ar~+488 nm) to plate and photocuring for thick coating and ink. The variation of UV-visible spectrum ofcompound 2 during irradiation indicates that photolysis of compound 2 is through its triplet state and it canbe quenched by O_2. The much quicker photobleaching of the photosensitive system suggests that there existscertain quick electron transfer reaction between compounds 1 and 2.     

硝化纤维素与甲基丙烯酸甲酯的均相接枝共聚

借助付里叶红外光谱、Ｘ－射线衍射以及电子显微技术，结合化学提纯方法，检测纤维素分子中主要基团、分子取向度和超分子结构形态等方面的变化，考察了均相条件下硝化纤维素与甲基丙烯酸甲酯接枝共聚物的形成与发生接枝共聚反应的部位，探索均相接枝的可能反应机理。     

CHARGE-TRANSFER AND ENERGY-TRANSFER IN THE PHOTO-INDUCED COPOLYMERIZATION OF 2-VINYLNAPHTHALENE WITH MALEIC ANHYDRIDE

The initiation mechanism of the copolymerization of 2-vinylnaphthalene with maleic anhydride was studied under irradiation of 365 nm. The excited complex was formed from (1) the local excitation of 2-vinylnaphthalene followed by the charge-transfer interaction with maleic anhydride and (2) the excitation of the ground state charge-transfer complex, and then it collapsed to 1,4-tetramethylene biradical for initiation. A1: 1 alternating copolymer was formed in different monomer feeds. Addition of benzophenone could greatly enhance the rate of copolymerization through energy-transfer mechanism.     

BARRIER PROPERTIES OF VINYLIDENE CHLORIDE/METHYL ACRYLATE COPOLYMER

A series of vinylidene dichloride (VDC) copolymers with methyl acrylate (MA) ascomonomer (3--12wt%), was prepared by free-radical suspension copolymerization. Thepermeability coefficients of the copolymers to oxygen and carbon dioxide were measured at1.0 MPa and at 30℃, and those to water vapor were measured at 30℃ and 100% relativehumidity All the VDC/MA copolymers studied are semicrystalline. As the MA contentincreases, the permeability coefficients of the copolymers to oxygen, carbon dioxide, andwater vapor are progressively increased, caused by decrease in crystalline fraction andincrease in free volume of VDC/MA copolymers.