Polymerization of cyclic monomers 9. Synthesis and radical polymerization of spirocyclic 2-vinylcyclopropanes

Summary 6,6-Diethyl- (1a) and 6-methyl-6-propyl-5,7-dioxa-4,8-dioxo-1-vinylspiro[2.5]octane (1b) were synthesized by the acetalization of 2-vinylcyclopropane-1,1-dicarboxylic acid with 2- or 3-pentanone. The new monomers were characterized by IR, ¹H NMR and ¹³C NMR spectroscopy. The radical polymerization of the monomers 1a and 1b, in addition of 6,6-methyl-5,7-dioxa-4,8-dioxo-1-vinylspiro[2.5]octane (1c) and (exo/endo)-7-ethoxycarbonyl-2-oxo-7-vinyl-bicyclo[4.1.0]heptane (1d), was carried out in bulk with 2,2`-azoisobutyronitrile (AIBN) as the initiator. The polymer yield with 1d was only low. The polymerization of the monomers 1a and 1c resulted in cross-linked polymers, whereas in case of the polymerization of monomer 1b soluble polymers in a high yield were obtained. Received: 17 February 1999/Revised version: 7 July 1999/Accepted: 7 July 1999     

Synthesis of novel organocobalt poly(arylene-vinylene)s containing (cyclobutadiene)cobalt moieties in the main chain

Summary Organocobalt poly(arylene-vinylene)s composed of 1,2- or 1,3- linkage at their cyclobutadiene moieties (3 and 4, respectively) were prepared by the Heck reaction of p-divinylbenzene with (cyclobutadiene)cobalt-containing monomers having two aryl bromide moieties (1 and 2, respectively). The number average molecular weights (M _n) of the obtained organocobalt poly(arylene-vinylene)s (3 and 4) were 4,100 and 4,000, respectively (GPC, on the basis of polystyrene). UV-vis spectra of 3 and 4 exhibited main π-π^* absorption peaks at 362 and 397 nm, respectively, which were ca. 60 nm bathochromically shifted from those of the corresponding monomeric units. Both polymers were found to show thermotropic liquid crystallinity in the range of room temperature to ca. 80 °C by employing differential scanning calorimetry (DSC) and the optical measurement using crossed polarizers. Received: 2 July 1999/Accepted: 29 July 1999     

Synthesis and characterization of poly(meth)acrylates containing tricyanocyclopropane ring for piezoelectric applications

Summary p-(2,2,3-Tricyano-3-carbomethoxycyclopropyl)phenoxyethyl acrylate (5a) and p-(2,2,3-tricyano-3-carbomethoxycyclopropyl)phynoxyethyl methacrylate (5b) were prepared by the reactions of bromomalononitrile with methyl p-(2-acryloyloxyethoxy)benzylidene-cyanoacetate (4a) and methyl p-(2-methacryloyloxyethoxy)benzylidenecyanoacetate (4b), respectively. Monomers 5a and 5b were polymerized with free-radical initiators to obtain the polymers with multicyanocyclopropane functionalities in the pendant group. The resulting polymers 6a and 6b were soluble in acetone and the inherent viscosities were in the range of 0.20–0.25 dL/g. Solution-cast films showed T _g values in the range of 130–150°C and piezoelectric coeffcients (d₃₁) of the poled films were 1.5–1.6 pC/N, which are acceptable for piezoelectric device applications. Received: 28 April 2000/Accepted: 26 June 2000     

Synthesis and properties of poly(phenylacetylene)s with pendant imino groups

Summary Polymerization of phenylacetylenes containing imino groups with a variety of transition metal catalysts was investigated. The monomers employed were N-(4-ethynylbenzylidene)aniline (1), N-(3-ethynylbenzylidene)aniline (2), N-(4-ethynylbenzylidene)-2,6-diisopropylaniline (3), N-(4-ethynylbenzylidene)-4-hexylaniline (4), N-(4-ethynylbenzylidene)butylamine (5), and N-(4-ethynylbenzylidene)octylamine (6). All of the monomers smoothly polymerized with [(nbd)RhCl]₂-Et₃N to give polymers in excellent yields, whereas no polymerization took place with W, Mo, and Fe catalysts. The produced polymers were orange to red solids and soluble in common organic solvents except for poly(1). UV-vis spectra of the polymers indicated that the main chains possess a similar degree of conjugation to that of poly(phenylacetylene). However, the stability of polymer backbone toward oxidative cleavage in solution remarkably improved, which is contributed by the electron-withdrawing character of imino groups. Received: 24 August 1999/Accepted: 29 September 1999     

New catalyst systems for polymerization of substituted acetylenes: W(NO)2(O2CR)2-MCl4(M=Ti, Sn)

Summary W(NO)₂(O₂CR)₂ - Lewis acid (LA) catalysts (LA=TiCl₄, SnCl₄; R=-CH(C₂H₅)(CH₂)₃CH₃) induce substituted acetylenes (phenylacetylene, propargyl ether, 1,6-heptadiyne, diphenylacetylene) to polymerize or oligomerize. Their catalytic ability strongly depends on the Lewis acid and solvent. The polymerization reactions of phenylacetylene always accompany the cycolotrimerization reactions. In the system with TiCl₄ in CH₂Cl₂ the yield of polymer equals to 56% at 80% conversion of a monomer. However, in the system with SnCl₄ in benzene, 42% cyclotrimers arise at 57% conversion of phenylacetylene. The mechanism of these reactions as well as the structure of the obtained polymers were determined. Received: 14 December 1998/Revised version: 25 July 1999/Accepted: 5 September 1999     

Synthesis of polyurethanes containing dioxynitrostilbene as a NLO-chromophore and their properties

Summary 3,4-Di-(2'-hydroxyethoxy)-4'-nitrostilbene (2) were prepared by the reaction of 2-iodoethanol with 3,4-dihydroxy-4'-nitrostilbene (1). Diol 2 was condensed with 2,4-toluenediisocyanate and 3,3'-dimethoxy-4,4'-biphenylenediisocynate to yield polyurethanes 3 and 4 containing the NLO-chromophore 3,4-dioxy-4'-nitrostilbene. Polymers 3 and 4 were soluble in common organic solvents such as acetone and DMSO. T _g value of the resulting polymers was in the range of 109–114°C. Electrooptic coefficient (r₃₃) of the poled polymer films were in the range of 20–25 pm/V at 633 nm. Polymers 3 and 4 showed a thermal stability up to 300°C in TGA thermograms, which is acceptable for NLO device applications. Received: 29 September 1999/Revised version: 19 November 1999/Accepted: 25 November 1999     

Synthesis and properties of conjugated copolymers having a tricarbonyl(arene)chromium and thiophene units in the main chain

Summary Palladium-catalyzed polymerization of η ⁶-(1,4-diethynylbenzene)tricarbonyl chromium (1) with 3-alkyl-2,5-dibromothiophene (2a-c) was carried out to give the corresponding alternating conjugated copolymers (5a-c) in good yields. The structures of the polymers were supported by ¹H NMR and IR spectra. The polymers obtained were soluble in common solvents such as THF, CH₂Cl₂, CHCl₃ and toluene. The molecular weights of the polymers were determined by GPC. Their thermal, optical and electrical properties were investigated in detail. Received: 18 March 2002 /Accepted: 1 April 2002     

Synthesis of poly(N,N-dimethylcarbamoylmethylene) as a polymer homolog of N,N-dimethylacetamide

Summary A novel polymer homolog of N,N-dimethylacetamide (DMAc) having amide groups on all main chain carbons, poly(N,N-dimethylcarbamoylmethylene) 1, was prepared by heating poly(di-t-butyl fumarate) 2 at 180 °C for 2 hours followed by treatment with hexamethylphosphoramide at 180 °C for 5 hours. The structure of the obtained polymer 1 was confirmed by ¹H-, ¹³C-NMR and IR spectroscopy. The polymer 1 actually showed the properties based on its repeating structures. 1 had the amphiphilicity and was soluble both in protic and aprotic solvents. Furthermore, 1 showed the miscibility with commodity polymers such as poly(N-vinylpyrrolidone), poly(vinyl alcohol) and poly(vinyl chloride). In comparison with another polymer homolog of DMAc, poly(2-methyl-2-oxazoline), the polymer 1 exhibited better miscibility with poly(N-vinylpyrrolidone). Received: 24 June 1999/Accepted: 19 July 1999     

Synthesis of star-shaped poly(vinyl ether)s by living cationic polymerization: Pathway for formation of star-shaped polymers via polymer linking reactions

Summary: Star-shaped polymers of isobutyl vinyl ether (IBVE) with a microgel core of an aliphatic divinyl ether (2) were synthesized in high yield on the basis of the living cationic polymerization with the HCl/ZnCl₂ initiating system. GPC analysis demonstrated that linear coupling products ("two-armed" polymers) and three-armed star polymers formed during the early stages of the linking reaction, and that subsequent coupling reactions between such low molecular weight star polymers gave star-shaped polymers with more arms. The number of arms ranged from 5 to 22, which increased with increasing [2]₀/[P^*] ratio and/or shortening the arm chain. Received: 11 April 2000/Accepted: 24 April 2000     

New optically active poly(amide-imide)s from N,N′-(bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic)bis-l-phenyl alanine and aromatic diamines: synthesis and characterization

In this work, new optically active poly(amide-imide)s (PAIs) having bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic diimide groups were prepared by the reaction of N,N′-(bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic)bis-l-phenyl alanine (4) as a diacid monomer with various readily available aromatic diamines. Triphenyl phosphite (TPP)/pyridine (Py) in the presence of calcium chloride (CaCl₂) and N-methyl-2-pyrrolidone (NMP) were successfully applied for direct polycondensation. The diacid (4) was synthesized by the condensation reaction of bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (1) with l-phenyl alanine (2) in acetic acid solution. The resulting new polymers were obtained in good yields, inherent viscosities ranging between 0.29 and 0.48 dLg⁻¹ and were characterized with elemental analysis, FT-IR, ¹H-NMR spectroscopy, specific rotation, and thermal gravimetric analysis (TGA, DTG) techniques. Thermogravimetric analysis indicated that the residual weight percent of polymers at 600 °C was between 53.80 and 56.21%, which show these are moderately thermally stable. In addition because of existence of chiral center and optical activity of these polymers, they have potential to be used as chiral stationary phase in chromatography technique for the separation of racemic mixtures.     

The effect of composition and the introduction of positive charge group (?N(CH3)2) on the multiphase morphology of polyurethane/polyacrylates interpenetrating polymer networks

A series of interpenetrating polymer networks (IPNs) of polyurethane/polyacrylates were synthesized. Their morphology was investigated by means of small‐angle X‐ray scattering (SAXS) and transmission electron microscope (TEM). The influence of an active positive charge group ( N(CH₃)₂) on the phase structure of the aforementioned IPNs was studied. The results show not only that the size of phase segregation zones varies with composition but also that the specific interfacial surface areas have a maximum when the weight ratio of polyurethane and polyacrylates is 1 : 2. Moreover, the introduction of an active positive charge group ( N(CH₃)₂) is an important way of increasing the miscibility between two component polymers. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1898–1904, 1999     

Controlled radical polymerization of styrene utilizing excellent radical capturing ability of diphenyl ditelluride

Summary The radical polymerization of styrene was investigated in the presence of diphenyl ditelluride (DPDTe) under varied conditions. In the polymerization without any radical initiator at higher temperature (125°C), the addition of DPDTe surely decreased the polymer molecular weight (M _n) while the polydispersity (M _w/M _n) was rather broad. The polymerization with benzoyl peroxide (BPO) as the initiator was also uncontrollable to afford polymers with broad M _w/M _n probably due to the redox side reaction of BPO with DPDTe. On the contrary, the precision control of M _n and the initiating end structure could be achieved by the polymerization with 2,2'-azobisisobutyronitrile (AIBN), that is, M _n increased in proportion to the molar ratio of monomer to initiator suggesting the suppression of bimolecular chain termination reactions by the excellent radical capturing ability of DPDTe. Received: 23 June 1999/Revised version: 11 August 1999/Accepted: 16 August 1999     

Synthesis of novel organoboron polymers by haloboration polymerization of bisallene compounds and their reactions

Summary. Novel organoboron polymers were prepared by haloboration polymerization of bisallene compounds. The polymers obtained have allylborane halide units in their main chain and can be expected as a novel type of reactive polymers. For example, the polymer prepared by haloboration polymerization between tribromoborane (1) and 1,2,10,11-dodecatetraene (2 b) was subjected to chain transformation reaction (dichloromethyl methyl ether rearrangement) to give the corresponding polyalcohol or polyketone. Haloboration-phenylboration polymerization of aliphatic bisallenes by using diphenylbromoborane also gave the corresponding polymers. Received: 8 July 1997/Revised: 23 July 1997/Accepted: 28 July 1997     

Novel ionenes with allyl pendant groups

Summary Novel ionenes with allyl pendant groups have been synthesized by condensation of N,N'- bisallylpiperazine with organic dihalides such as 1,4-dichlorobutane, 1,6-dibromohexane and 1,4-dichloromethylbenzene. The polymers are readily soluble in water and have low molecular weights. The structure of the ionenes has been identified by spectroscopic techniques. The concentrated aqueous solutions of the resulting ionenes can be crosslinked by t-butylhydroperoxide as a radical initiator to give transparent hydrogels. The ionenes also act as an crosslinking agent in copolymerization with high concentrations of acrylic acid in the presence of K₂S₂O₈ as a radical initiator in water at 65°C. Received: 29 July 1999/Revised version: 28 October 1999/Accepted: 28 October 1999     

Synthesis and characterization of novel polyurethanes containing tricyanocyclopropane ring for piezoelectric applications

Summary 1-(2',2',3'-Tricyano-3'-carbomethoxycyclopropyl)-3,4-di-2'-hydroxyethoxybenzene (4) was prepared by the reaction of bromomalononitrile with methyl 3,4-di-(2'-hydroxyethoxy)benzylidenecyanoacetate (3). Diol 4 was condensed with 3,4-toluenediisocyanate and 3,3'-dimethoxy-4,4'-biphenylenediisocynate to yield polyurethanes 5 and 6 containing multicyanocyclopropane functionalities in the pendant group. The resulting polymers 5 and 6 were soluble in common organic solvents and the inherent viscosities were in the range of 0.25–0.30 dL/g. Polyurethanes 5 and 6 showed a thermal stability up to 300°C in TGA thermograms. Solution-cast films showed T _g values in the range of 100–130°C and piezoelectric coeffcients (d₃₁) of the poled polymer films were 1.8–2.0 pC/N, which are acceptable for piezoelectric device applications. Received: 14 December 2000/Accepted: 22 January 2001     

Ionic Conductivity of Cross-linked Polymethacrylate Derivatives/Cyclophosphazenes/Li<Superscript>+</Superscript> Salt Complexes

The role of cyclophosphazenes with oxyethylene chains (N₃P₃(OCH₂CH₂)_nOCH₃, (n = 3, 3, n = 7.2, 4) and N₄P₄[OC₆H₄O(CH₂CH₂O)_7.2CH₃]₈ (8) for the synthesis and ionic conductivity in polymethacrylate networks was studied. Reflecting the structural features of cyclophosphazenes, the ⁷Li NMR spectra of the mixture of 3 and LiN(SO₂CF₃)₂ showed that more than 40% of the Li⁺ salt could exist as a free ion at room temperature. Similar values were obtained for 4 and 8. Cross-linked methacrylate polymers (12–14, and 16–18) were prepared from the reaction of poly(ethylene glycol) methyl ether methacrylate and poly(ethylene glycol) dimethacrylate both in the presence of these cyclophosphazenes which act as molecular imprinting molecules (method II, M-II) and without the cyclophosphazene (method I) DSC studies of the imprinted polymer, 12(20)/3/Li⁺ system after removal of the cyclophosphazene showed that the glass transition temperature range (ΔT_g) becomes significantly narrower compared to that of the unimprinted 11(20)/3/Li⁺ system, where cross-linked polymer 11(20) was prepared in the absence of the cyclophosphazenes (method I, M-I). The ionic conductivity of the Li⁺/cross-linked polymer system was improved by the subsequent readdition of the cyclophosphazenes. The 12(20)/3/Li⁺ complex showed a conductivity of 1.1 × 10⁻³ S/cm at 90 °C, which was two times higher than that of the 11(20)/3/Li⁺ complex. The effectiveness of the small molecule imprinting technique for the preparation of cross-linked polyelectrolytes with high conductivity and mechanical stability is discussed. We dedicate this paper to Professor Christopher W. Allen for his creative, pioneering work in inorganic ring and inorganic-organic hybrid polymers.     

Synthesis and characterization of poly(organophosphazenes) bearing Schiff's base linkages

Summary Two new classes of Schiff's base poly(organophosphazene)s have been synthesized and characterized. The substitution degree of the Schiff's base linkage was found for the products of the form, [NP(O-Ph-CHO)_x(O-Ph-CH=N-Ph-R)_y]_n(polymer II series), where R are H, OCH₃, OH(p), OH(m) and -N=N-Ph, was less than 35%, while the products of the second class, [NP(OCH₂CH₂OCH₂CH₂O-Ph-CHO)_x(OCH₂CH₂OCH₂-CH₂O-Ph-CH=N-Ph-R)_y]_n (polymer III series), where R are H, COOH(m), COOH(p), NO₂, and OCH₃, marked 65% on the average. The solubility of the polymers in the common organic solvents was found very poor, except such strong polar or aprotic solvents at elevated temperature. The existence of flexible spacer group connected to the Schiff's base linkage has greatly influenced the thermal properties of the polymers. DSC measurements revealed about 100°C of melting transition for the polymer II series, while 214°C for the polymer III series with exhibiting multistage of thermal transition. The DSC results gave some evidences that the products of polymer III series have potentials for the thermotropic liquid crystalline polymers. Received: 12 February 1999/Revised version: 5 April 1999/Accepted: 6 April 1999     

Synthesis and properties of nonlinear optical chromophores and polymers containing 6-nitroquinoline as π-electron acceptor

Summary Two nonlinear optical (NLO) methacrylate monomers, 2-methyl-acrylic acid 2-(ethyl-{4-[2-(6-nitro-quinolin-2-yl)-vinyl]-phenyl}-amino)-ethyl ester (5) and 2-methyl-acrylic acid 6-{3-[2-(6-nitro-quinolin-2-yl)-vinyl]-carbazol-9-yl}-hexyl ester (7) were newly synthesized and copolymerized with methylmethacrylate to give NLO polymers, P1 and P2. These polymers were well soluble in organic solvents and showed glass transition temperatures at 145 °C and 114 °C, respectively. The number average molecular weights (Mn) were 26,600 for P1 and 9,300 for P2. The SHG coefficients (d₃₃) of corona-poled films of P1 and P2 measured with 1.064 μm Nd-YAG laser were 32.2 pm/V and 17.6 pm/V, respectively. Received: 29 September 1998/Revised version: 7 December 1998/Accepted: 11 December 1998     

Synthesis and optical properties of poly(phenylenevinylene) modified with 3,4-bis(phenylene)-3-cyclobutene-1,2-dione moiety

Summary A new class of soluble poly(p-phenylenevinylene)-modified conjugated polymers with a simple aromatic unit of 3,4-bis(phenylene)-3-cyclobutene-1,2-dione in the main chain was synthesized by the dehalogenation polycondensation and the Heck reaction. The monomer and the polymers were characterized by FT-IR, ¹H-NMR, UV-visible, Elemental Anaylsis, TGA and DSC. The resultant polymers were obtained as yellow powder, formed the brittle film from the DMAc solution. These polymers were soluble in polar aprotic solvents, such as NMP, DMAc, DMF and DMSO. The present polymers show absorption bands in the range of 286∼325nm, corresponding to the π-π^* electronic transition of the conjugated polymer backbones. The photoluminescence spectrum of the polymer 1 shows a peak at 471nm while the polymer 2 has the peak at 522nm with DMAc solution, in the blue emission region. Received: 21 January 1999/Revised version: 2 April 1999/Accepted: 5 April 1999     

Thermal cyclodehydration of aromatic precursor polymers to polybenzoxazole and polyimide; their thermal and mechanical properties

Summary Two precursor polymers, polyhydroxyamide (PHA) and poly(amic acid) (PAA) for polybenzoxazole (PBO) and polyimide (PI), respectively, showed large endothermic enthalpies (ΔH) in DSC thermograms. The values of enthalpy become smaller, and then unobservable with increasing cyclodehydration. The cyclization onset temperature (T₁) of the PHA and PAA occurred at 255–309 °C and 175–234 °C, respectively. Of the two precursor polymers, T₁ showed an increase with increasing cyclodehydration. The initial decomposition temperature (T₂) showed no significant change dependent on cyclodehydration. The tensile properties of the two precursors were enhanced drastically with increasing degree of cyclodehydration. PHA was shown to have excellent solubility only in strong acids at room temperature. In contrast, PAA was soluble in all the testing solvents at room temperature. Received: 12 November 1999/Revised version: 19 December 1999/Accepted: 22 December 1999