Segmental exchange polyacetal‐polyether in the cationic copolymerization of trioxane with dioxolane catalyzed by BF<sub>3</sub> in the presence of polyethers

Penczek,; Fejgin, Jerzy; Sadowska, W.; Tomaszewicz, M.

doi:10.1002/macp.1968.021160120

Cited by 32 publications

(7 citation statements)

References 16 publications

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“…[31][32][33] The ring-opening copolymerization of TOX can be initiated by Lewis acid such as BF 3 O(Et) 2 , TiCl 4,34 and CH 3 COClO 4 . 35 Penczek and coworkers 36 studied the solution copolymerization of TOX and a small amount of DOX initiated by BF 3 O(n-Bu) 2 and found that the unstable fraction content of the copolymer increased with increasing conversion, indicative of a higher reactivity of DOX than that of TOX toward the copolymerization.…”

Section: Introductionmentioning

confidence: 98%

Synthesis of copolymer from 1,3,5‐trioxane and 1,3‐dioxolane catalyzed by Maghnite‐H⁺

Beloufa¹,

Sahli²,

Belbachir³

2009

J of Applied Polymer Sci

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Copolymers (polyoxymethylene) were prepared by cationic copolymerization of 1,3,5‐trioxane (TOX) with 1,3‐dioxolane (DOX) in the presence of Maghnite‐H+ (Mag‐H+) in solution. Maghnite is a Montmorillonite sheet silicate clay, with exchanged protons to produce Mag‐H+. Various techniques, including 1H‐NMR, 13C‐NMR, FT‐IR spectroscopy, and Ubbelohde viscometer were used to elucidate structural characteristics properties of the resulting copolymers. The influence of the amount of catalyst, of dioxolane (DOX), temperature, solvent, and time of copolymerization on yield and on intrinsic viscosity of copolymers was studied. The yield of copolymerization depends on the amount of Mag‐H+ used and the reaction time. We also propose mechanisms involved in the synthesis of copolymer (polyoxymethylene). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

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Section: Introductionmentioning

confidence: 98%

Synthesis of copolymer from 1,3,5‐trioxane and 1,3‐dioxolane catalyzed by Maghnite‐H⁺

Beloufa¹,

Sahli²,

Belbachir³

2009

J of Applied Polymer Sci

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“…In 1968, Penczek et al reported for the first time on the cationic ring opening copolymerization of 1,3,5-trioxane and 1,3-dioxolane, leading to microspheres. 10 Then, direct synthesis of polyester particles during the polymerization of heterocyclic monomers was patented in the early 1970s. 11 Subsequent papers on the ionic and/or pseudoionic dispersion polymerization were published only very recently.…”

Section: Introductionmentioning

confidence: 99%

“…The conditions allowing us to obtain uniform latexes and microspheres in radical polymerization are well defined. − On the other hand, the knowledge of ionic and/or pseudoionic dispersion polymerization is very limited. In 1968, Penczek et al reported for the first time on the cationic ring opening copolymerization of 1,3,5-trioxane and 1,3-dioxolane, leading to microspheres . Then, direct synthesis of polyester particles during the polymerization of heterocyclic monomers was patented in the early 1970s .…”

Section: Introductionmentioning

confidence: 99%

Poly(l,l-lactide) Microspheres by Ring-Opening Polymerization

1996

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Poly(l,l-lactide) microspheres were synthesized directly during the ring-opening precipitation polymerizations of l,l-lactide. The polymerizations were carried out in heptane−1,4-dioxane (4:1 v/v) mixed solvent in the presence of various poly(dodecyl acrylate)-g-poly(ε-caprolactone) copolymers (poly(DA−CL)) used as surface active agents. Copolymers with different molecular weights, different average number of poly(ε-caprolactone) grafts per macromolecule, and different molecular weights of these grafts were used. Poly(l,l-lactide) microspheres with number-average diameters (D̄ n) from 2.46 to 4.07 μm and with polydispersity parameters (D̄ v/D̄ n, where D̄ v denotes the volume-average diameter) from 1.08 to 1.45 were obtained. The dependence of D̄ n and D̄ v/D̄ n on the structure and on the concentration of poly(DA−CL) was investigated. The narrow diameter polydispersity (D̄ v/D̄ n = 1.08) was obtained when poly(DA−CL), containing an average of 1.3 poly(ε-caprolactone) grafts (with M̄ n = 4700 g/mol) per copolymer macromolecule, was used at a concentration of 1.6 g/L, i.e., below the critical concentration of micellization of this surface active agent (ccm = 5.1 g/L). Poly(l,l-lactide) microspheres contained from 1.5 to 6.6 wt % of the unreacted lactide. The optical purity of monomer (95.4%) and of the corresponding polylactide from microspheres (from 91.0% to 94.9%) indicated that polymerization in the investigated heterogeneous system proceeds with retention of configuration on the chiral carbon atom. The DSC studies revealed that the crystallinity of the poly(l,l-lactide) microspheres was strongly dependent on the thermal history of these materials and on the concentration of the surface active agent used for the polymerization. Microspheres partly composed of crystalline and/or amorphous poly(l,l-lactide) were obtained.

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“…Chain transfer to residual water can also take place and justifies the experimentally observed hydroxyl end groups, whereas transfer to polymer (transacetalization) can generate macrocycles when it occurs intrachain or lead to random redistribution of sequences (scrambling) when it occurs interchain, , the latter process becoming particularly critical for the thermal stability of the final product in the case of copolymerization.…”

Section: Introductionmentioning

confidence: 73%

Cationic Copolymerization of 1,3,5-Trioxane with 1,3-Dioxepane: A Comprehensive Approach to the Polyacetal Process

et al. 2009

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The bulk copolymerization of 1,3,5-trioxane (TOX) with 1,3-dioxepane (DXP) initiated by perchloric acid hydrate(s) is studied at 80 °C with DXP/TOX initial ratios from 20/80 to 3/97 w/w. As usually observed for the polyacetal synthesis, the polymerization takes place within seconds to tenths of seconds and proceeds in two steps, a homogeneous (“induction”) period, followed by a very rapid heterogeneous propagation−crystallization step. The influence of the reaction conditions was systematically examined (diluent of initiator, comonomer concentration, transfer to residual water), and the products formed during the short induction period were identified using NMR. The difference between the respective basicities of the comonomers is such that during the induction period the initiation takes place on the DXP, and for DXP initial concentrations above its equilibrium value [DXP]eq,ss the early formed soluble polymer is either the homopolymer or a DXP highly enriched copolymer. The precipitation step starts only after the concentration of DXP is lowered enough to allow the copolymerization with TOX to proceed significantly and the poly(oxymethylene) −[CH2−O] n − sequences to reach their critical crystallization length. This critical concentration was found constant whatever the initial DXP/TOX ratio. For initial concentrations lower than [DXP]eq,ss (i.e., DXP/TOX ≤ 5/95 w/w), the DXP cannot homopolymerize and should be consumed by single unit insertion during a copolymerization effective since the early beginning. Therefore, during the further heterogeneous propagation−crystallization step, the insertion of two successive DXP units in the copolymer chain becomes highly improbable. The copolymer formed by both propagation and transacetalization processes is either inserted into the crystal (or its immediate interface) if only isolated DXP units are present along the poly(oxymethylene) chain or rejected in the amorphous phase if preformed DXP sequences are present. The latter situation occurs for DXP/TOX initial ratios ≥10/90 w/w. This is in agreement with our previous measurements of the crystal partitioning coefficient, which confirmed that the tetramethyleneoxy −[(CH2)4−O]− units from DXP are progressively rejected into the increasing amorphous fraction for initial DXP richer compositions. Coherent chemical pathways are proposed for the overall process, which are in accordance with the experimental behaviors during both homogeneous and heterogeneous steps.

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Segmental exchange polyacetal‐polyether in the cationic copolymerization of trioxane with dioxolane catalyzed by BF₃ in the presence of polyethers

Cited by 32 publications

References 16 publications

Synthesis of copolymer from 1,3,5‐trioxane and 1,3‐dioxolane catalyzed by Maghnite‐H⁺

Synthesis of copolymer from 1,3,5‐trioxane and 1,3‐dioxolane catalyzed by Maghnite‐H⁺

Poly(l,l-lactide) Microspheres by Ring-Opening Polymerization

Cationic Copolymerization of 1,3,5-Trioxane with 1,3-Dioxepane: A Comprehensive Approach to the Polyacetal Process

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Segmental exchange polyacetal‐polyether in the cationic copolymerization of trioxane with dioxolane catalyzed by BF3 in the presence of polyethers

Cited by 32 publications

References 16 publications

Synthesis of copolymer from 1,3,5‐trioxane and 1,3‐dioxolane catalyzed by Maghnite‐H+

Synthesis of copolymer from 1,3,5‐trioxane and 1,3‐dioxolane catalyzed by Maghnite‐H+

Poly(l,l-lactide) Microspheres by Ring-Opening Polymerization

Cationic Copolymerization of 1,3,5-Trioxane with 1,3-Dioxepane: A Comprehensive Approach to the Polyacetal Process

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Segmental exchange polyacetal‐polyether in the cationic copolymerization of trioxane with dioxolane catalyzed by BF₃ in the presence of polyethers

Synthesis of copolymer from 1,3,5‐trioxane and 1,3‐dioxolane catalyzed by Maghnite‐H⁺

Synthesis of copolymer from 1,3,5‐trioxane and 1,3‐dioxolane catalyzed by Maghnite‐H⁺