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In the present study, structural analyses using synchrotron grazing incidence X-ray scattering, specular reflectivity and ellipsometry were performed on thin films of two novel polynorbornene derivatives, chiral poly(norbornene acid methyl ester) and racemic poly(norbornene acid n-butyl ester), which are potential low dielectric constant materials for advanced microelectronic and display applications. These analyses provided important information on the structure, electron density gradient across the film thickness, chain orientation, refractive index and thermal expansion characteristics of the polymers in substrate-supported thin films. The structural characteristics and properties of the thin films depended on the tacticity of the polymer chain and were further influenced by the film thickness and thermal annealing history.

(−)-(1S,2R)-Norbornene-2-carboxylic acid alkyl esters (alkyl = Me, Bz, L-menthyl, or D-menthyl) were successfully prepared by the Diels–Alder reaction of cyclopentadiene with (R)-(−)-pantolactone-O-yl acrylate followed by epimerization and column chromatography. The enantiomeric excess was 99.9%. These monomers were polymerized by Pd(II)-based catalysts, and high yields of the polymers were obtained. The methyl ester gave an optically active polymer of high optical rotation (monomer [α]D = −24.7, polymer [α]D = −98.5). This high rotation value of the polymer was attributed to the isotactic chain regulation of the polymer. This high rotation was not observed with methyl esters prepared by the transesterification of menthyl esters. The stereoregular polymer exhibited notable resonance peaks at 39 ppm in 13C NMR spectra. No crystallinity was observed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1263–1270, 2006

Cinnamate group is well-known for the dimerization reaction by ultraviolet irradiation and their anisotropic dimerization are used for aligning liquid crystals. In this work, we found that cinnamate groups attached to the flexible polymer backbone could be reacted by thermal energy as well as UV irradiation. Cinnamate group of flexible polymers shows different molecular orientation of cycloadducts, comparing with conventional polymers, and it also participates in insolubilization reaction by additional thermal treatment. The thermal insolubilization reaction of flexible cinnamate polymer might be appropriate for the enhancement of molecular orientation.

A styrene monomer t BQSt, having a tert -butyloxycarbonyloxy ( t -BOC)-protected quinizarin dye precursor as a pendent, has been copolymerized with N -(tosyloxy)maleimide (TsOMI) to obtain a dual functional polymer P( t BQSt/TsOMI). The polymer P( t BQSt/TsOMI), as a single component photoimaging system without using an external photoacid generator (PAG), was applied for fluorescent photopatterning by dry process based on the chemical amplification (CA) process. The TsOMI units in the polymer chains were responsible for photochemical generation of p -toluenesulfonic acid by UV exposure and the acid generated in the solution cast polymer film induced the catalytic deprotection of acid labile t -BOC groups of the quinizarin dye precursors. Accordingly, the quinizarin moieties were regenerated in the polymer chains by the CA process, thereby recovering the original color and fluorescence of the quinizarin dye. Fluorescent patterns were readily delineated on the thin polymer films by imagewise UV exposure even without a wet development process.

Di- and triblock copolymers of poly(ethylene oxide) (PEO) and poly( dl -valine-co- dl -leucine) were synthesized by ring-opening polymerization of N-carboxyanhydride (NCA)s of dl -valine and dl -leucine initiated by amine-terminated PEOs. The resulting block copolymers were characterized by 1 H NMR , FT-IR, DSC, and wide-angle X-ray diffraction (WAXD). Differential scanning calorimeter revealed that the melting temperature of triblock copolymer was lower than that of diblock copolymer and the study of WAXD patterns of triblock copolymer indicated that PEO segments are stretched during the copolymerization as shown in the formation of complex. The self-assembly behaviors of these di- and triblock copolymers in the aqueous solution showed various forms.

Various prestructured cyclic monomers were synthesized and polymerized to construct the copolymers of controlled mer sequence. Substituted 8-, 10- and 12-membered cyclic olefins were polymerized by ROMP catalyst, i.e., W(OAr) 2 Cl 4 /Et 4 Pb. Those polymers obtained were the alternating terpolymers of butadiene and vinyl monomers. Cyclic monomers with mesogenic groups as substituents were prepared and polymerized successfully. The resulting polymers were highly liquid crystalline exhibiting rather lower transition temperatures than their monomeric analogs.

A homopolymer having pendentt-Boc-protected quinizarin moieties has been prepared for patterned fluorescence images. The homopolymer P{t-BQN (2-norbornenylmethyl di-tert-butoxycarbonylquinizarin)}5 was prepared by palladium-catalyzed addition polymerization. Thet-Boc-protecting groups of the polymer were efficiently removed during chemical amplification process and revealed original properties of quinizarin, allowing patterned fluorescence images in the polymer film.

Glycolide (GL) and e-caprolactone (CL) were copolymerized in bulk at relatively high temperatures using stannous octoate as a catalyst. To investigate the relationship among microstructure, thermal properties, and crystallinity, three series of copolymers prepared at various reaction temperatures, times, and comonomer feed ratios were prepared and characterized by 1 H and 13 C NMR, DSC, and wide-angle X-ray diffraction (WAXD). The 600-MHz l H NMR spectra provided information about not only the copolymer compositions but also about the chain microstructure. The reactivity ratios (r G and r G ) were calculated from the monomer sequences and were 6.84 and 0.13, respectively. In terms of overall feed compositions, the sequence lengths of the glycolyl units calculated from the reactivity ratios exceeded those measured from the polymeric products. Mechanistic considerations based on reactivity ratios, monomer consumption data, and average sequence lengths are discussed. The unusual phase diagram of GL/CL copolymers implies that the copolymer melting temperature does not depend on its composition alone but rather on the nature of the sequence distribution. The DSC and WAXD measurements show a close relationship between polymer crystallinity and the nature of the polymer sequence.

Fully multi-alicylic polymers designed for use as 193 nm photoresist materials have been synthesized by vinyl addition polymerization of tetracarbocyclic norbornene derivatives, t-butyl tetracyclo[4.4.0.1.2,5 17,10]dodec-8-ene-3-carboxylate (t-BDN) and 3-acetoxytetracyclo-[4.4.0.1.2,5 17,10]dodec-8-ene (AcODN). The alicyclic polymer backbones of these polymers provide plasma etch resistance and mechanical properties. Two pendant groups were introduced to provide the desired lithographic functions: the t-butyl carboxylate group as a carboxylic acid functionality masked by a protecting group undergoes acid-catalyzed thermolysis; and the acetoxy polar group influences adhesion, wettability and dissolution properties of the polymers. The polymer showed an acceptable high transmittance at 193 nm and good adhesion property. The plasma etch rates of the copolymer poly(t-BDN-co-AcODN) (85:15) using CF4/CHF3 mixed gas were 1.01 times with respect to a novolac based resist. The 0.2 μm line-and-space patterns were obtained with a dose of 45 mJ cm−2 using a KrF excimer laser stepper.

The thermal behavior of isothermally crystallized syndiotactic polystyrene (SPS) and 70/30 SPS/poly(2,6-dimethyl-1,4-diphenylene oxide) (PPO) blend was investigated by differential scanning calorimetry. Pure SPS, which was crystallized at Tc=220 and 240°C had single melting endotherm and multiple endotherms, respectively, whereas the 70/30 SPS/PPO blends showed the opposite behavior with respect to Tc. Investigation by polarizing optical microscopy and small angle X-ray scattering revealed that the rejected impurity (PPO in blend and noncrystallizable chains with low molecular weight in pure SPS) during SPS crystallization resides between primary lamellae of SPS and thus the recrystallization strongly suppressed for the pure SPS crystallized at Tc=220°C and the 70/30 SPS/PPO blend crystallized at Tc=240°C. This may induce single melting endotherm. In the pure SPS crystallized at Tc=240°C and the 70/30 SPS/PPO blend crystallized at Tc=220°C, the rejected impurity resided between SPS crystalline fibrils, which consist of lamellae. This may allow recrystallization between the primary lamellae which would exhibit sharp multiple melting endotherms.

It is well known that brittle polymers can be considerably toughened by the incorporation of miscible amorphous polymers or a thermoplastic elastomer. The effect of rubber toughening was studied via reactive extrusion to investigate the fracture mechanism and morphology controls of syndiotactic polystyrene (SPS)/poly(2,6-dimethyl-1,4-diphenylene oxide) (PPO) blends. Successful rubber toughening was achieved in compatibilization using reactive extrusion. The reactive polystyrene (RPS) as a compatibilizer and styrene–ethylene/butylene–styrene block copolymer (SEBS) as an impact modifier were used in an extrusion experiment. The impact strength was highly dependent on the blending condition and the composition. The best result was obtained by 2-step mixing; the first mixing of PPO with RPS (1.0 phr oxazoline content) and functionalized SEBS (f-SEBS, 0.4 phr maleic anhydride content) then followed with SPS mixing. Increase in RPS level gave rubber particle size reduction due to the reactions at the interfaces among polymer phases, as demonstrated by the decreased tan δ value. The storage modulus (E′) of SPS/PPO blends was decreased with increasing PPO content.

α,ω-Hydroxy-terminated vinyl prepolymers were prepared by radical polymerization of methyl methacrylate, butyl acrylate, styrene and vinyl acetate in the presence of allyl alcohol. The butyl acrylate prepolymer of molecular weight 3100 and functionality 2.2 was prepared by the following condition; [BA]=3.85 mol/l, [ACPROL]=0.128 mol/l and [AA]=0.90 mol/l at 110°C. The polyurethane reactions of the resulting telechelic polymers with hexamethylene diisocyanate were carried out to obtain vinyl polymer-based polyurethanes.

A new series of the processable poly(terephthalylidene) derivatives containing single atom linkage were prepared by condensation reactions between bis(4-formylphenyl)ether or sulfide and 2,5-bis(hexyloxyl)-1,4-xylene bis (triphenyl phosphonium chloride), respectively. The resulting polymers were soluble in common organic solvents and could be spun-cast on glass plate coated with ITO electrode obtaining highly transparent homogeneous thin films. Chemical structures of the polymer were confirmed by IR, UV-visible, 1 H and 13 C NMR spectra. We observed successfully the electroluminescence spectra and maximum peaks at 525 nm and 505 nm from the devices made by the synthesized polymers. The present polymers have the strong absorption band at around 395 nm and 383 nm, which are due to the π – π ∗ transition of the conjugated segments of corresponding polymers. I–V curve showing typical rectifying diode characteristics. EL spectrum of the polymer was very similar to the PL spectrum indicating that the origins of the light emission in both cases are the same.

Styrene monomer was mixed with quaternary ammonium montmorillonites(org-MMTs) and polymerized in the presence of radical initiator. The resulting materials showed an expansion of interlayer distance. These hybrid materials exhibited higher thermal stability compared with the virgin polystyrene(PS) or PS/pristine-MMT microcomposite. PS/Bz-MMT, containing benzyl-unit similar to styrene in org-MMT, exhibited higher decomposition temperature even for MMT loading as low as 0.3wt.% compared with other PS/org-MMT hybrids. It was found that the structural affinity between styrene monomer and the organic group of org-MMT plays an important role in the structure and the properties of hybrid materials.

As an extension of studies in the anionic polymerization of activated cyclopropanes with electronically push-pull substituents, p-substituted phenylcyclopropane-l,l-dicarbonitriles having MeO, Me, H, Cl, and NO2 as substituents were prepared. The electronic effects of substituents upon the ring-opening reaction during anionic polymerizations were examined by determining the rate constants of polymerizations, conversions and molecular weights of the resulting polymers. The rate constants of polymerization(kp) in DMSO by 2 mole% cyanide ion at 35°C were p-MeO=0.45, p-Me=0.14, p-H=0.07, p-Cl=0.06 and p-NO2=0.011 liter/mole.sec, and the rate constants of polymerization in DMSO by 5 mole% pyridine at 35°C were p-Me0=0.048, p-Cl=7.6 × 10−3 and p-NO 2 =1.64 × 10 − 3 liter/mole.sec. , respectively. The electronic effect exerted by substituents were well consistent with the Hammett relationship(log k/ko = σ ϱ) when Brown's σ+ constants were used. The reaction sensitivity constants(ϱ) obtained from cyanide ion initiator were −1.0 and −0.94 for pyridine initiation. These results indicate that the anionic ring-opening polymerization of p-substituted phenylcyclopropanes is carried out via highly conjugated zwitterionic transition state in the ring opening reaction. Furthermore, in the case of the polymerization initiated by pyridine or triethylamine, the formation of macrozwitterion during polymerization is a feasible mechanism. As an extension of studies in the anionic polymerization of activated cyclopropanes with electronically push-pull substituents, p-substituted phenylcyclopropane-1,1-dicarbonitriles having MeO, Me, H, Cl, and NO2 as substitutents were prepared. The electronic effects of substituents upon the ring-opening reaction during anionic polymerizations were examined. The rate constants of polymerization (kp) in DMSO by 2 mole% cyanide ion at 35°C were p-MeO=0.45, p-Me=0.14, p-H=0.07, p-Cl=0.06 and p-NO2=0.011 liter/mole.sec., and the rate constants of polymerization in DMSO by 5 mole% pyridine at 35°C were p-MeO=0.048, p-Cl=7.6 × 10−3 and p-NO2=1.64 × 10−3 liter/mole.sec. The electronic effect exerted by substituents were well consistent with the Hammett relationship (log k/ko=σ ϱ) when Brown's σ+ constants were used. The reaction sensitivity constants (ϱ) obtained from cyanide ion initiator were −1.0 and −0.94 for pyridine initiation. These results indicate that the anionic ring-opening polymerization of p-substituted phenylcyclopropanes is carried out via highly conjugated zwitterionic transition state in the ring opening reaction.

Two different tocopherol-containing amphiphilic monomers, [[(tocopheryloxy)-carbonyl ]-methyl ] [ 2-(methacryloyloxy)ethyl ]dimethylammonium chloride(3a) and [[ (tocopheryloxy)penta(ethoxy)carbonyl ]methyl ]2-(methacryloyloxy)ethyl]dimethylammonium chloride(3b), were synthesized and polymerized. The formation of polymeric closed vesicles having diameters ranging from 200 to 5200 A was confirmed by electron micrographs, entrapment of [ 14 C]sucrose, permeability measurements and get filtration. The polymeric vesicles showed reduced permeability and enhanced thermodynamic stability. Antioxidative activities were determined by the thiocyanate method confirming that polymeric tocopherols also exhibited significant activities.

Diethyl triacontanedioate (CH 3 CH 2 O 2 C(CH 2 ) 28 CO 2 CH 2 CH 3 ) and triacontane-1,30-diol (HO(CH 2 ) 30 OH) were prepared and condensed to synthesize poly(triacontamethy-lene triacontanedioate) (PTRM). The properties of PTRM were compared with those of commercial low density polyethylene (LDPE), and enzymatic degradation of the PTRM was investigated. PTRM showed not only high melting point of 113 °C and a thermal stability comparable to LDPE. The elongation at break is low (about 5%) and the tensile strength is around 12.5 MPa, higher than that of LDPE. The small contact angles indicate that PTRM has good wettability compared with LDPE. The increase of total organic carbon by Rhizopus arrhizus lipase and the resulting change of surface morphology confirmed that PTRM is biodegradable.

trans-Polypentenamers with thermotropic liquid-crystalline side chains cholesteryl and cyanobiphenyl were prepared by ring-opening polymerization of vinylcyclopropane monomers with proper substituents. Molecular weights of the polymers were in the range of 25000 to 80000 and the ratios of weight- to number-average molecular weights Mw/Mn were between 3.3 and 3.8. The glass transition temperature values of the polymers were 35°C (4a) and 39°C (4b). Monomers 3a and 3b present cholesteric and smectic mesomorphism, respectively. On the other hand, polymers 4a and 4b present only a smectic mesophase.

A new type of processable electroluminescent polymer containing tertiary amine linkage was prepared by typical Wittig reaction between bis(4-formylphenyl) n-butylamine and diphosphonium salt. The resulting polymer was highly soluble in common organic solvents so that it could be spun-cast onto glass plate coated with ITO electrode to give highly transparent homogeneous thin film. The molecular weight of the polymer determined by gel permeation chromatography using polystyrene standards is Mn = 4,500, Mw = 11,600. The structure of the polymer was confirmed by IR, UV-visible, and 1H-and 13C-NMR spectroscopy. We observed successfully the electroluminescence peaked at around 530 nm from the device made of the synthesized polymer. The current-voltage (I-V) curves showed typical rectifying diode characteristic.

Electroluminescent polymers [Ph-N(Bu)-PhCH=CR-Ph-CR=CH] n (R=H, CN) have been synthesized by the Knoevenagel or Wittig condensation reaction. These polymers showed a relatively low threshold voltage compared with a block copolymere having similar conjugated units.

The photoinitiated elimination of methoxy groups of poly(p-phenylene-1-methoxyethylene) and the photochemical doping of the resulting poly(phenylenevinylene) (PPV) were investigated. Upon irradiation and then heat treatment at 150°C, poly(p-phenylene-1-methoxyethylene) containing triphenylsulfonium hexafluoroantimonate was converted to PPV. The resulting PPV was observed to be conductive and its conductivity was 10 -2 -10 -3 S/cm. By a lithographic procedure, we produced a conducting pattern doped photochemically in a nonconjugated poly(p-phenylene-1-methoxyethylene) matrix

Synthesis of butadiene-based sequence-controlled copolymers that are composed of commercial monomers such as styrene, butadiene, and ethylene was investigated. New substituted cyclododecadiene derivatives, 9-phenyl-1,5-cyclododecadiene was synthesized by reductive-phenylation method from 1,5-cyclododecadiene-9-one and was polymerized with tungsten-based catalyst systems to obtain a microstructure-controlled terpolymer. A sequence-controlled 2 : 1 : 1 terpolymer of butadiene, styrene and ethylene was successfully synthesized. The glass transition of the terpolymer occurred at -33.6°C. © 1995 John Wiley & Sons, Inc.

Solubilization of cholesterol in water with cholesterol-containing poly(N-vinyl-2-pyrrolidone) was studied. The non-ionic amphiphilic polymers were synthesized via copolymerization of cholesterol-based monomers with N-vinyl-2-pyrrolidone; the copolymers were dissolved isotropically in water to form hydrophobic microdomains solubilizing cholesterol efficiently. Electron micrographs revealed that the amphiphilic polymers undergo aggregational changes from random microphases to bilayers as free cholesterol is incorporated into the polymeric hydrophobic domains.

7-Methyl-2-phenyl-1,4,6-trioxaspiro[4,5]dec-7-ene (1) and 7-methyl-2-phenyl-1,3,6-trioxaspiro[4,5]dec-7-ene (2) were prepared by [4+2] Diels-Alder reaction in a Parr-reactor. While monomer 1 polymerized only via opening of pyran ring, monomer 2 which has the oxygen atoms properly positioned to facilitate the double ring-opening underwent cationic polymerication with mainly double ring opening. Volume expansion (6.7%) was observed in polymerization of monomer 2.

It was found that methyl (Z,E or E,Z)-3,7-cyclodecadienecarboxylate undergoes ring opening metathesis polymerization by the catalyst system WCl 4 (OAr) 2 /PbEt 4 to afford a 1:2 copolymer of methyl acrylate and butadiene.

The NMR and IR spectral data of the polymers indicate that the radical polymerization of this cyclic disulfane proceeds clearly via a 1,8-type ring opening process to yield the polymer [CH 2 CH=C(CH 3 )SO 2 CH 2 CH 2 CH 2 SO 2 ] n

La photopolymerisation en masse de la dioxolane avec ou sans photosensibilisant et a temperature inferieure a 80°C donne uniquement le polymere (CH 2 -CO-CH 2 OCHPh) n . La polymerisation photochimique a temperature superieure a 80°C ou radicalaire donne des polymeres de structure complexe resultant de modes de polymerisation differents (vinylique, avec ouverture de cycle, avec elimination)

La polymerisation radicalaire dans le benzene du 4-phenyl-2-propenylene-1,3-dioxolane donne le polyester [CH 2 -CH=CH-COO-CH 2 -CH(Ph)] n . Discussion du mecanisme.

In the search for the potential method to extract the free cholesterol from certain biological systems, a nonionic polymeric amphiphile was prepared from cholesterol-based monomer and acrylamide. This copolymer dispersed well forming vesicles when sonicated and was found to be effective for the extraction of cholesterol in water as the experiment with [14C]cholesterol indicated. Extraction became more effective as temperature was raised.

In search for the new synthetic methods which may lead to the copolymers of controlled mer sequences, several new carbocyclic and heterocyclic monomer systems such as 1,1-disubstituted 2-vinylcyclopropanes, 1-(p-anisyl)-2-vinylcyclopropanes, substituted 3,4-dihydro-2H-pyrans, substituted 4-vinyl-2-oxetanones and α-vinyl cyclic sulfones were synthesized and their polymerization behaviors were investigated. And other promising monomer systems were also examined.

Sonication of a non-ionic polymerizable chlosterol-based amphiphile, 1-ethenyl-3-(8-(cholest-5-en-3β-yloxy)- 3,6-dioxaoctyl)-2-pyrrolidone, in water resulted in the formation of bilayer vesicles. The vesicle formation was evidenced by transmission electron microscopy and[ 14 C] sucrose entrapment. Polymeric vesicles, prepared by polymerization in the bilayer, showed increased stability.

The radical polymerization of 10-methylene-9,10-dihydroanthryl-9-spirophenylcyclopropane is found to proceed with aromatization via 100% ring opening. Aromatization energy is strong enough driving force to promote 100% ring opening to insert a p-anthrylene group into the backbone of the polymer

Ring opening metathesis polymerization of 4-methyl-6-phenyloctene yielded the linear polymer [CH 2 CH=CHCH 2 CH 2 CH(CH 3 )CH 2 CH(Ph)] n , rubbery at room temperature and exhibiting a glass transition at ca. -6.6°C

Ring-Opening Metathesis Polymerization of 4,6-Diphenylcyclooctene: 2:1 Alternating Copolymer of Styrene and Butadiene

A novel photoimaging process in thin films has been disclosed by taking advantage of photolithographic techniques based on chemical amplification concept. The key materials utilized in the process are norbornene-derived quinizarin dye molecules protected with acid-labile tert-butoxycarbonyl (t-Boc) blocking groups.

Nanoemulsions have recently become increasingly important as potential vehicles for the controlled delivery of cosmetics and for the optimized dispersion of active ingredients in particular skin layers. The preparation of conventional nanoemulsions requires mainly high-pressure homogenization, which is unproductive and requires high energy due to its lower efficiency, limiting their practical applications. In order to solve these problems novel nanoemulsions were studied using a model system of pseudo-ternary water/emulsifier/paraffin oil. Nanoemulsions were prepared by stirring a mixture of the tocopherol-containing block co-polymer emulsifier PPG-20 Tocophereth-50, paraffin oil, and distilled water at the Θ-point using weight fractions of the dispersed phase (φ) of 0.31 to 0.82 and an emulsifier content of 1.0 to 9 wt.%. The emulsifying property of PPG-20 Tocophereth-50 in nanoemulsions was compared with that of the conventional emulsifiers Tocophereth-43, a mixture of polysorbate 60 and sesquioleate (3/1), and phospholipids. Also the emulsifying property of PPG-20 Tocophereth-50 in the more hydrophilic oils caprylic/capric triglyceride and octyldodecanol was compared with that in paraffin oil. The stability and morphology of the resulting nanoemulsions were studied by visual inspection, optical microscopy, particle size analysis, and cryo-scanning electron microscopy. In the nanoemulsion systems containing caprylic/capric triglyceride and octyldodecanol, respectively, as an oil phase PPG-20 Tocophereth-50 showed emulsification properties similar to those in paraffin oil. The conventional emulsifiers Tocophereth-43, a mixture of polysorbate 60 and sesquioleate (3/1), and phospholipids did not give nanoemulsions with high-speed stirring. The block co-polymer nonionic emulsifier PPG-20 Tocophereth-50 was found to produce stable nanoemulsions of mean droplet diameters ranging from 204 to 499 nm. The emulsification method of high-speed stirring at the Θ-point using PPG-20 Tocophereth-50 was found to be very effective for the preparation of stable nanoemulsions useful for applications in skincare cosmetics, cosmeceuticals, and drugs.

To investigate further the anionic ring-opening polymerization of substituted cyclopropane 2-phenylcyclopropane-1,1-dicarbonitrile (I), 2-ethylcyclopropane-1,1-dicarbonitrile (II), and 2,2-dimethylcyclopropane-1,1-dicarbonitrile (III) were prepared and polymerized with sodium cyanide in N,N-dimethylformamide. Under these conditions only I polymerized well. The polymer in I was soluble in hot sulfolane and the inherent viscosity was 0.5 dl/g (conc. 0.5 g in 100 ml). This result supports the previously postulated mechanism that a cyclopropane ring with properly positioned electron-donating and electron-withdrawing substituents can polymerize by opening the bond activated by a “push–pull” system.

2-Methoxy-6-ethoxy-5-cyano-3,4-dihydro-2H-pyran (1a), 2-isobutoxy-6ethoxy-5-cyano-3,4-dihydro-2H-pyran (1b), and 2,6-diethoxy-3-methyl-5-cyano-3,4-dihydro-2H-pyran (1c) were prepared by (4 + 2) cycloaddition reaction of ethyl α-cyanoacrylate with the corresponding vinyl ethers. Compounds 1a-c were ring-open polymerized by cationic catalyst to obtain alternating head-to-head (HH) copolymers. For comparison, head-to-tail (HT) copolymer 3a was also prepared by free radical copolymerization of the mixture of the corresponding monomers. The H–H copolymer exhibited minor differences in its 1H-NMR and IR spectra, but in the 13C-NMR spectrum significant differences were shown between the HH and HT copolymers. Glass transition temperature (Tg) of HH copolymer was higher than that of the corresponding HT copolymer, but thermal decomposition temperature of the HH copolymer was lower than that of the HT copolymer. Compounds 1a and 1b copolymerized well with styrene by cationic catalyst, but compound 1c failed to copolmerize with styrene. All of the H-H and H-T copolymers were soluble in common solvents and the inherent viscosities were in the range 0.2–0.5 g/dL.

Among the four 1,1-disubstituted 2-vinylcyclopropanes, diethyl 2-vinylcyclopropane-1,1-dicarboxylate (Ia), 2-vinylcyclopropane-1,1-dicarbonitrile (Ib), ethyl 1-cyano-2-vinylcyclopropanecarboxylate (Ic), and 1,1-diphenyl-2-vinylcyclopropane (Id), Ib and Ic polymerized well with sodium cyanide in N,N-dimethylformamide. Ib was most reactive and a polymer (IIb) from Ib exhibited an inherent viscosity of 1.05 dl/g (concentration of 1.0 g in 100 ml of 95% H2SO4). All experimental results indicated that the polymerization proceeded by ring opening and that the structure of the polymers had pendant vinyl groups. The polymer IIc from Ic was soluble in common solvents like acetone, but IIb was soluble only in 95% H2SO4. Reactions of those compounds with benzenethiolate ion in ethanol yielded addition products that supported the ring-opening polymerization of those monomers. In the postulated mechanism of polymerization cyanide ion attacks the carbon of a cyclopropane ring with electron-releasing vinyl group and the resulting anion is thereby stabilized by two electron-withdrawing substituents. The propagation takes place by the reaction of the anion with another monomer molecule.

Copolymerisation radicalaire avec l'acrylonitrile et l'α-cyanoacrylate d'ethyle dans le benzene a 60°C