THE POLYMERIZATION OF AROMATIC AND HETEROCYCLIC DINITRILES

This review is a concise survey about the works in our laboratory on the polymerization of aromatic and heterocyclic dinitriles, including the polymerization kinetics and mechanism, synthesis of heterocyclic dinitriles, the structure of polymers, and the correlation between the structures of dinitriles and polymerization rates and thermal performances of Polymers.     

THE AROMATIC AND HETEROCYCLIC DINITRILES AND THEIR POLYMERS. Ⅸ. THE POLYMERIZATION KINETICS OF 4, 4''-BIPHENYLDICARBONITRILE*

The polymerization kinetics of 4,4'-biphenyldicarbonitrile catalyzed by complex of 4,4'-biphenyl-dicarbonitrile with ZnCl_2 was studied. The cyano group concentration was measured by infrared spectroscopic analysis using potassium ferricyanide as the internal reference. The results proved that the polymerization is a second order reaction, and the activation energy of polymerization is 12.4 kcal/mol. The polymerization rates of 4,4'-biphenyldicarbonitrile catalyzed by other seven complexes were also measured. The polymerization mechanism was discussed.     

AROMATIC AND HETEROCYCLIC DINITRILES AND THEIR POLYMERS ⅪⅤ. STUDY ON THE CATALYSTS OF THE POLYMERIZATION OF AROMATIC NITRILES*

Various catalysts for the polymerization ot aromatic nitriles were investigated. It was found that Lewis acid-metal is a preferable catalyst system for the polymerization of aromatic nitriles, and the polymerization rate is about 10 times faster than Lewis acid alone. The polymerization rate of benzonitrile catalyzed by Lewis acid and different metals was measured, and the activity of metals was in the following decreasing order ,magnesium, zinc, sodium, calcium. Furthermore, the polymerization of benzonitrile catalyzed by different Lewis acid and zinc was also investigated.     

AROMATIC AND HETEROCYCLIC NITRILES AND THEIR POLYMERS ⅩⅥ. THE POLYMERIZATION KINETICS OF 4, 4′-BIPHENYLDICARBONITRILE CATALYZED BY LEWIS ACID-METAL SYSTEM

The polymerization kinetics of 4, 4′-biphenyldicarbonitrile using cuprous chloride-zinc system as catatyst was investigated. the concentration of unreacted cyano group was measured by infrared spectroscopic analysis using potassium ferricyanide as the internal reference. It was found that the polymerization rate is directly proportional to the concentrations ofcyano group, cuprous chloride and zinc, and the activation energy of the polymerization is as Tow as 18.4 KJ/mol. In addition, the other kinetics parameters were obtained and discussed.     

AROMATIC AND HETEROCYCLIC DINITRILES AND THEIR POLYMERS ⅩⅢ. POLYMERIZATION KINETICS OF BENZONITRILE AND THE STRUCTURE OF PRODUCTS

The polymerization kinetics of benzonitrile were studied, and the formation rate constants of s-triazine structure and linear polymer were determined. The influence of polymerization temperature and the amount of zinc chloride as catalyst on the ratio of linear to cyclic structure were also investigated, and the obtained results were discussed.     

AROMATIC AND HETEROCYCLIC NITRILES AND THEIR POLYMERS ⅩⅦ. THE POLYMERIZATION KINETICS OF CYANOPYRIDINES AND CHARACTERIZATION OF THE FORMED POLYMER*

The polymerization rates of three cyanopyridines catalyzed by cuprous chloride-zinc system are measured, and the structure of the formed polymer is also determined. Compared with aromatic nitrile, cyanopyridines polymerize faster and form polyconjugated polymer with skeleton—(C=N)—_n instead of triazine structure. This chain-polymer possesses semiconductive property, and can be converted into conductive material by thermal treatment. In addition, the polymerization kinetics of 3-cyanopyridine catalyzed by 3-cyanopyridinium perchlorate is investigated. It is found that the polymerization rate is directly proportional to the concentrations of monomer and catalyst, and the activation energy of the polymerization is 103.1 KJ/mol.     

AROMATIC AND HETEROCYCLIC NITRILES AND THEIR POLYMERS XIX:THE POLYMERIZATION OF SUBSTITUTED BENZONITRILES CATALYZED BY COBALTIC ACETYLACETONATE

The polymerization kinetics of 4, 4'-biphenyldicarbonitrile and other substituted ben-zonitriles catalyzed by cobaltic acetylacetonate was studied. The structure of polymer ofdifferent substituted benzonitrile was also determined. It is found that the rate of polymeri-zation and the structure of polymer is greatly affected by the substituent of benzonitriles.     

AROMATIC AND HETEROCYCLIC NITRILES AND THEIR POLYMERS ⅩⅧ. THE POLYMERIZATION KINETICS OF BENZONITRILE CATALYZED BY METAL ACETYLACETONATE

The bulk polymerization of benzonitrile catalyzed by Co(Ⅱ), Co(Ⅲ) and Fe(Ⅲ) acetylacetonate was studied. The results of kinetics study show that the rate of polymerization was proportional to first power of the concentration of catalyst and second power of the concentration of monomer.     

STRUCTURAL EFFECT ON VINYL POLYMERIZATION INITIATED WITH AROMATIC TERTIARY AMINE

The polymerization mechanism of various vinyl monomers in the presence of aromatic tertiary amines has been studied. It was found that the mechanisms of different monomers are varied with the structures of monomers. Those monomers, such as methacrylic esters containing α-CH_3 group on the double bond could be polymerized with aromatic tertiary amine in the absence of light, while the monomers without α-CH_3 group, such as methyl acrylate, acrylonitrile etc. would polymerize only under light.The structural effects, both of the monomer and the amine, on the rate of photopolymerization were studied. The activities of monomers and amines may be arranged in the following orderMonomer: AN>MA>VA>St Amine: DMT>DMA>DMB>DNAIt is revealed that both the electro-negative group on the double bond of monomer which acts as an acceptor and the electro-positive group on the nitrogen atom of amine which acts as a donor would effectively increase the rate of photopolymerization.     

A STUDY ON THE STRUCTURE AND PROPERTIES OF POLYBUTYLALDEHYDE FORMED IN LOW TEMPERATURE PLASMA

The polybutylaldehyde obtained by plasma polymerization was investigated by means of IR, X-ray diffraction, GC-MS, elementary analysis, TEM, electron diffraction and contact angle measurements etc. The results showed that the polymer formed in plasma is amorphous crosslinked polymer, and its backbone is made of carbon atoms. The surface energy of the polymer film is independent of the polymerization conditions. No addition reaction has taken place in the carbonyl group of butylaldehyde in the plasma condition. The result of the wettability measurements showed that the polymer film is generally hydrophobic and the surface energy of the film is about 41 dyn/cm, in which the dispersion force contribution is the majority. The electron diffraction proved that some crystal substance, even the single crystals were present in the polymer. X-ray diffraction also proved the presence of crystal and showed about 15% crystaUinity fraction.     

STUDY ON THE EFFECT OF POLYSTYRENE SULFONIC ACID MACROMOLECULES ON THE POLYMERIZATION OF ACRYLAMIDE

The effect of polystyrene sulfonic acid (PSSA) macromolecules on the polymerization of acrylamide (AM) has been studied. It was found that the rates of polymerization of AM were greatly increased in the presence of PSSA in the polymerization system.The maximum value of the rate of polymerization of AM was obtained when the ratio of [—SO_3H]: [AM] reached 3:1. When the insoluble crosslinked PSSA was used instead of the soluble one, this effect decreased considerably. The interaction between molecules of PSSA and AM was determined by infrared spectroscopy, elementary analysis and X-ray photoelectron spectroscopy. The combination form, —SO_3-NH_3~ CO—, formed between sulfonic group and amide group was found to be existed since the infrared absorption band of —NH_2 shifted from 3400cm~(-1) to 3150 cm~(-1), the binding energy of electron N_(18) changed from 399.7 eV to 401.3 eV, and the atomic ratio of N to S of the products was similar to the ratio of reagents. Based on these experimental results, the mechanism of AM polymerization in the presence of PSSA is proposed. The initial step is the combination of AM with sulfonic group to form —CONH_3~ , then followed by polymerization on the PSSA macromolecule. The role of PSSA on the polymerization of AM is discussed.     

HETEROCYCLIC SCHIFF BASE NEODYMIUM COMPLEX AS CATALYST FOR RING-OPENING POLYMERIZATION OF ε-CAPROLACTONE

An aromatic heterocyclic Schiff base neodymium complex bearing thiazole was synthesized and its activity in the ring-opening polymerization ofε-caprolactone(CL)was examined.The conditions of the CL/Nd molar ratio,monomer concentration,polymerization time and temperature were investigated.Activities of ca.171 kg/Nd·h were obtained under the optimum condition(CL/Nd=1600(molar ratio),[CL]=2.26 mol L~(-1),1 h at 50℃),giving a poly(ε-caprolactone)(PCL)of number-average molecular weight M_n=5.4×10~4 and molecular weight distribution MWD=1.96.The conversion of CL monomer as high as 94% was observed after polymerized for one hour.The mechanism of coordination polymerization has also been illustrated.     

SYNTHESIS AND POLYMERIZATION OF OLIGO (OXYETHYLENE) MACROMONOMER

This paper reports the synthesis of methoxyoligo (oxyethylene) methacrylate (MEO_n , n is the repeating unit number of (CH_2CH_2O) in the macromonomer), and its polymerization in different solvents. MEO_n is prepared through such two independent reactions as (1) anionic polymerization of oxirane initiated by potassium alkoxide and (2) end-capping of methoxy oligo(oxyethylene) by methacrylic group. The n value can be conveniently controlled over the range of 5 ～30 by varying the molar ratio of oxirane to initiator and the molecular weight distribution of MEO_n be narrowed by increasing reaction time only in step (1). MEO_n thus obtained shows a rapid polymerization in water and benzene respectively, and both give water-soluble polymers as long as suitable conditions are used.     

ELECTROCHEMICAL POLYMERIZATION OF ANILINE IN PHOSPHORIC ACID AND THE PROPERTIES OF POLYANILINE

The behavior of the electrochemical polymerization of aniline in a weak acid, phosphoric acid, is very similar to that in strong acids, i.e. its polymerization rate increases quickly with the electrolysis time. The FTIR spectra of polyaniline samples synthesized in phosphoric acid indicate that the counter ion H2PO4^- is present in both the oxidized form and the reduced form of polyaniline. The counter ion plays an important role in adjusting the pH value at the electrode surface of polyaniline during the oxidation and reduction processes. As a result, a pair of redox peaks still appear in cyclic voltammograms of polyaniline in a solution of sodium sulfate of pH 5.5 and in a solution of NaH2PO4 of pH 7.0,respectively, at low potential scan rate; and the color of polyaniline film also changes with applied potential at pH 7.0. Thus,the pH region for the electrochemical activity and the electrochromism of polyaniline is extended to pH 5.5 for a solution of sodium sulfate and to pH 7.0 for a solution of NaH2PO4. The conductivity of polyaniline is 3.3 S cm^-1, depending on the concentration of phosphoric acid used in the stage of polymerization of aniline. The result of elemental analysis of polyaniline is presented here.     

THE EFFECTS OF N-2-HYDROXYETHYL-N-METHYL-p-TOLUIDINE ON METHYL METHACRYLATE RADICAL POLYMERI-ZATION AND ACRYLONITRILE PHOTOINDUCED POLYMERIZATION

The effects of N-2-hydroxyethyl-N-methyl-p-toluidine (HMT) on MMA polymerization using organic peroxide as an initiator and on AN photoinduced polymerization have been investigated respectively. The kinetics of polymerization and the overall activation energy of polymerization were determined. Based on kinetics study and the end group analysis of the polymer obtained by UV spectrum method, the initiation mechanism is proposed.     

SYNTHESIS OF NEW AROMATIC POLY（AMIDE IMIDE）S FROM UNSYMMETRICAL EXTENDED DIAMINE CONTAINING A PHTHALAZINONE MOIETY

The direct polymerization of an unsymmetrical kink non-coplanar heterocyclic diamine (1) with various aromatic bis(trimellitimide)s (2a-e) using triphenyl phosphite and pyridine as condensing agents could generate a series of new aromatic poly(amide imide)s (3a-e) containing the kink non-coplanar phthalazinone heterocyclic units in the polymer main chains with inherent viscosities of 0.58-0.66 dL/g. The polymers are readily soluble in a variety of solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidinone, pyridine and m-cresol and can be cast to form flexible and tough films. The glass transition temperatures of polymers (T8) are in the range of 301-327℃, and the temperatures for 5% weight loss in nitrogen are in the range of 498-521℃.     

KINETICS AND MECHANISM OF PHOTOINDUCED POLYMERIZATION BY α,α-DIMETHOXY-α-PHENYL ACETOPHENONE

α,α-dimethoxy-α-Phenyl acetophenone (DMPA) is an efficient and thermally stable photoinitiator. Here its spectral characteristics in the transient state were shown. The transient species were identified as a benzoyl radical and a dimethoxyi benzyl radical that played a primary initiation role in polymerization. The kinetics and mechanism of the bulk polymerization of MMA were investigated. The exponent of DMPA concentration and k_p/k_1~(1/2) value were found to be 0.5 and 0.066 mol(-1/2)l~(1/2)s~(-1/2), respectively. The existence of oxygen led to obtain the polymer with higher molecular weight, which can be attributed to the occurrence of the subsequent polymerization induced by active polymer end group. In the photocrosslinking reaction, the dependence of DMPA content on initial rate has been found. A principal reason is that the sample contained higher percentage of DMPA has higher light-absorbed efficiency. In solid film, higher concentration of DMPA is permitted to be used because there is little excited state self-quenching effect in the rigid medium.     

STUDIES ON ORGANO-MOLYBDENUM AND TUNGSTEN COMPOUNDS(Ⅲ)——CATALYTIC POLYMERIZATION OF ACETYLENE BY M-O-C BOND-CONTAINING COMPLEXES OF Mo AND W

Catalytic polymerization of acetylene in the presence of n5-C5H5-M-(CO)3 R (M=Mo,W;R=CH3-,C2H5-) has been studied.The results show that these complexes possess catalytic activities for the polymerization and copolymerization of monosubstituted acetylene.The catalytic mechanism has been preliminarily discussed.It is suggested that the active species be metal-car-bene.In our previous publications we reported the synthesis of some new Fischer's molybdenum and tungsten-carbene complexes and catalytic activity for alkyne polymerization.The results show that the activity of Fischer's molybdenum-carbene is higher than that of tungsten.The catalytic polymerization of alkyne by M-σ-c bond-containing complexes of molybdenum and tungsten has not been reported yet in literature.Therefore,four M-σ-C bondontaining complexes of molybdenum and tungsten were synthesized by using the method reported in the literature,and catalyst polymerization of alkyne by these complexes was examined.     

VINYL RADICAL POLYMERIZATION INITIATED WITH CERIC ION AND ETHYL N, N-DIETHYLDITHIOCARBAMYL ACETATE SYSTEM

Acrylamide polymerization initiated with a redox initiation system consisting of cericion and ethyl N, N-diethyldithiocarbamyl acetate (EDCA) has been studied. It was foundthat the polymerization rate equation is in good agrement with that of a redox initiatedpolymerization, and the overall activation energy of the polymerization was determinedto be 25.2kJ·mol~(-1). Accordingly, the system belongs to a redox initiator. The initiationmechanism was proposed based on the end group analysis using FT-IR, UV spectroscopies.Analysis results revealed that the N, N-diethyldithiocarbamyl radical produced from theredox reaction of EDCA with ceric ion can initiate acrylonitrile (AN) polymerization andform the end group on PAN. The resulting PAN was photopolymerized with butyl acrylate(BA) to form PAN-b-PBA block copolymer.     

STUDIES ON THE KINETICS AND INITIATION MECHANISM OF ACRYLAMIDE POLYMERIZATION USING CERIC/ACETOACETANILIDE SYSTEM AS INITIATOR

It is found that acetoacetanilide possesses very high promoting reactivity towards ceric ion in initiating polymerization of vinyl monomer. The kinetics of acrylamide polymerization and the activation energies were studied. The initiation mechanism of ceric/acetoacetanilide is proposed on the basis of experimental results of FT-IR and ESR.