Diels‐alder polymers: Polyphenylenes containing alternating phenylene and triphenylphenylene units (1)

New aromatic thermally stable polymers prepared by the Diels-Alder polymerization between diacetylenes and bis(cyclopentadienones) are described. The diacetylenes used were 1,3-diethynyl-5-(trimethylsilyl)benzene, 1,3-diethynyltetrafluorobenzene, 4,4'-diethynylbenzophenone, 2,5-diethnylthiophene, l,3-bis[2-(methoxycarbonyI)ethynyl]benzene, l,3-bis(l-bromoethynyl)benzene, and l,3-bis[2- [(iVV-dimethylaminoJcarbonyl]ethynyl]benzene. Polymerization of these monomers with 4,4'-(oxy-p-phen-or 4,4'-(oxy-p-phenylene)bis[2,3,5-tris('3-methylphenylicyclopentadienone] yielded polymers soluble in tetrahydrofuran, p-dioxane, cyclohexylbenzene, Nmethylpyrrolidinone, toluene, xylene, chloroform, chlorobenzene, or N^V-dimethylformamide. The molecular weights of the polymers were strongly affected by the concentration of the reactants in the polymerization reaction. Size-exclusion chromatography of the polymers versus polystyrene standards yielded Mñs and MJMJs from 5000 to 140 000 and from 1.4 to 4.2, respectively. The polymers had glass transition temperatures (Tg's) ranging from 245 to 270 °C and onsets of decomposition of 310-480 °C both in air and in argon. The polymers form strong, coherent optically transparent films in thicknesses of 1-7 pm and have potential as photodefinable organic dielectrics.

Section: Resultsmentioning

confidence: 99%

Diels-Alder Polymerization between Bis(cyclopentadienones) and Acetylenes. A Versatile Route to New Highly Aromatic Polymers

Kumar¹,

Neenan²

1995

“…Caled for C27H220: C, 89.47; , 6.12. Found: C, 89.55; H, 6.59. 2,5-(4-Biphenylyl)-3,4-diphenylcyclopentadienone (7). A mixture of 1.0 g (2.8 mmol) of 1,3-(4-biphenylyl)-2-propanone ( 9) and 0.6 g (2.8 mmol) of benzil in 10 ml of triethylene glycol was heated to 100°a nd held there until solution was complete.…”

Section: Methodsmentioning

confidence: 99%

Catenation and Kinetics of the Diels-Alder Step-Growth Reaction in the Synthesis of Phenylated Polyphenylenes

Stille¹,

Noren²

1972

Self Cite

The cluster function given by eq 12 is shown in Figure 6f for an athermal solution arid in Figure 6g for a system with x = 0.45. The cluster function determined from eq 6 is given byThe cluster function derived from eq 7 differs from eq 16 only in the additional term of eq 16, muz/(l + mc). Calculated curves based on these equations are shown in Figure 6i.The Flory-Leonard equation with x = 0.45 gives computer curves in good agreement with the experimental data, whereas x = 0.6 gave a better fit to the al -v1 data ( Figure 5). The Wee equations, derived to determine the effect of flexible side chains on phase equilibria, do not fit as well. This is not surprising, as the rodlike character of the main chain still plays a significant role in the activity expression at low concentration, in contrast to the Flory-Leonard expression.It is clear from the comparison of the experimental data with various theories that the free energy associated with the initial solution process is controlled by polymer side chainsolvent mixing. This is in marked contrast to more dilute polymer solutilons, where the rodlike behavior of the molecules is of major importance to the thermodynamics of this system.3s12ABSTRACT : The Diels-Alder step-growth polymerization of biscyclopentadienones with bisacetylenes, which can produce either para or rneta catenation in the benzene ring formed from the reaction, was shown by a model reaction to yield both types of catenation. The model reaction of 3-(4-biphenylyl)-2,4,5-triphenylcyclopentadienone with 4-ethynylbiphenyl gave products in which the ratios (para to meta) varied with the reaction temperature from 0.55 at 100" to 1.0 at 255". The application of the Arrhenius law to thle data yields a difference in theenthalpy of activation of (AH,* -AH, *) of -1.6 kcal/mol and a difference in the entropy of activation (ASrn * -AS, *) of 3.0 eu. The polymerization reaction of 3,3'-(oxydi-p-phenylene)bis(2,4,5-triphenylcyclopentadienone) followed a second-order rate law, and the rate constants at the temperatures of 225, 200, and 175" were found to be 1 14 X 10-3, 4.6 X I./(mol sec), respectively. The Arrhenius activation parameters as calculated from the rate constants were A H * = 12.4 kcal/mol and AS* = -48 eu, consistent with a Diels-Alder reaction which requires a low AH and a large negative AS. and 2.6 x he Diels-Alder reaction, or diene synthesis, has long

“…Activities calculated from eq [6][7][8] are reasonably insensitive to and x at fixed c and m. If c and m are taken as adjustable parameters, numerous combinations will give a reasonable fit to the experimental data. Shown in Figure 5 is a curve calculated from eq 6 and 8 with = 0, x = 150, c = 1.5, and m = 0.1.…”

Section: Resultsmentioning

confidence: 98%

Vapor Sorption of N,N-Dimethylformamide on Poly(γ-benzyl α,L-glutamate)

H.¹,

Miller²

1972

Solvent activities for poly(Y-benzyl L-glutamate) solutions in V./V'-dimethylformamide have been determined at 25, 20, and 10°in the concentration range 70-100 vol % polymer. The results indicate that solvent activity is insensitive to temperature at constant composition in the concentration and temperature ranges studied. No evidence was found for the coexistence of two phases or for ordered side chains in the polypeptide. The results are compared with theories of solutions of rodlike molecules.