AM1 semiempirical computational analysis of the homopolymerization of spiroorthocarbonate

ABSTRACT:The visible-light photohomopolymerization reactivities of several monofunctional oxiranes were evaluated using photodifferential scanning calorimetry (PDSC). Two oxiranes, styrene oxide and 1-methoxy-2-methyl propylene oxide, were selected for copolymerization reactivity studies with five substituted 1,5,7,11-tetraoxaspiro[5.5]undecanes (TOSUs). Reaction mixtures contained a diaryliodonium salt photoacid initiator and a ␤-diketone photosensitizer. Experimentally determined reaction enthalpies were compared with calculated theoretical values to assess percent conversion. Relative reactivities were evaluated by comparing induction and exotherm peak maximum times. Results of AM1 semiempirical quantum mechanical calculations of reaction energetics were compared to experimental findings for selected polymerizations. IR spectral changes were consistent with oxirane and TOSU ring opening. The effect of temperature on the photopolymerization reactivity characteristics of glycidyl methylphenyl ether alone and in combination with unsubstituted TOSU was also studied.

Section: Resultsmentioning

confidence: 60%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Visible light‐induced polymerization of monooxiranes and 1,5,7,11‐tetraoxaspiro[5.5]undecanes

Pinzino¹,

Chappelow²,

Holder³

et al. 2002

“…E act was computed as the difference between the Δ H f of the transition state and the Δ H f of the van der Waals complex formed by the reactant molecules. The application of these methods to related expanding monomer and oxirane cationic polymerization systems has been previously described 26, 27. Proton affinities (PA) were calculated by a previously reported method 28…”

Section: Methodsmentioning

confidence: 99%

“…Computational methods based on quantum mechanics have recently been applied to determine activation energies and enthalpies of polymerization for a variety of monomers 25–27. These calculations can help predict which reactions are most favored energetically.…”

Section: Introductionmentioning

confidence: 99%

Photopolymerization of an expanding monomer with an aromatic dioxirane

Smith

Pinzino

Chappelow

et al. 2004

ABSTRACT:The objective was to study the photocationic polymerization of an expanding monomer, 1,5,7,11-tetraoxaspiro[5.5]undecane (TOSU), and an aromatic dioxirane, bisphenol A diglycidyl ether (BADGE). Both homopolymerizations and binary polymerizations were conducted. The homopolymer, poly(TOSU), was found to be a linear poly(carbonate), which was soluble in acetone. Poly-(BADGE) products contained ether linkages in addition to primary and secondary alcohol functionalities. Binary polymerization products varied depending on the irradiation time and length of dark cure.13 C-NMR analysis of binary polymerizate products revealed peaks not seen in homopolymer spectra consistent with the formation of copolymer linkages. Mass spectrometry data revealed peaks consistent with oligomers that contained both TOSU and BADGE mer units. The structures of key reaction products were proposed.

Tetraoxaspiroalkanes for polymerization stress reduction of Silorane resins

Chappelow

Pinzino

Chen

et al. 2008

This study involved the synthesis and characterization of tetraoxaspiroalkane monomers and evaluated their potential to reduce polymerization stress when formulated in a Silorane resin system. The tetraoxaspiroalkane monomers had two main structural features (a) two different types of core ring structures (a 1,5,7,11-tetraoxaspirocyclic ring or a 2,4,8,10-tetraoxaspirocyclic ring) and (b) four different types of ring substituents (normal alkyl, allyloxyalkyl, trimethylsilylalkyl, or oxabicycloalkyl). The resin formulations contained (a) 20 mol % of a 1,5,7,11-or 2,4,8,10-tetraoxaspiroalkyl monomer; (b) a phenylmethylsilane containing two oxabicycloheptyl groups; (c) a cyclotetrasiloxane containing four oxabicycloheptyl groups; and (d) a photocationic initiator system. Three main aspects were studied (a) the photoreactivity of the formulations using PDSC, (b) photopolymerization stress, and (c) mechanical properties (flexural elastic modulus, ultimate strength, and work of fracture) which were measured using an electromagnetic mechanical testing machine. The main findings were (a) formulations containing 2,4,8,10-tetraoxaspiroalkane monomers had measured net enthalpies greater than those containing 1,5,7,11-tetraoxaspiroalkane monomers, and above those calculated for addition of an inert diluent; (b) all formulations containing tetraoxaspiroalkane monomers exhibited photopolymerization stress values that were 40-99% less than the nonaddition control; (c) the formulation containing a 1,5,7,11-tetraoxaspiroalkane monomer with an oxirane functionality had mechanical properties that were not significantly different from the nonaddition control.