Polymerization Of Oxetane Research Articles

Chain termination in polymerization of substituted oxetanes in the presence of boron trifluoride etherate

It has been shown that the polymerization of oxetanes with azidomethyl substituents initiated by boron trifluoride etherate in the absence and the presence of ethylene glycol proceeds via chain termination with fluorine atom transfer. This reaction results in the formation of a polymer that is monofunctional with respect to hydroxyl groups and contains a fluorine atom at one of the chain ends. With the use of 19F NMR spectroscopy, the number-average functionality of polymer with respect to fluorine atoms was studied. The methods of suppressing the aforementioned reaction, whose intensity decreases during a decrease in the polymerization temperature and an increase in the ethylene glycol concentration, were considered. In the absence of ethylene glycol, the chain termination with fluorine atom transfer is the main reaction of chain-propagation restriction.

Competitive Processes in Controlled Cationic Ring‐Opening Polymerization of Oxetane: a Lotka‐Volterra Predator‐Prey Model of Two Growing Species Competing for the same Resources

AbstractSummary: The activation‐deactivation pseudo‐equilibrium coefficient Qt and constant K0 (=Qt x PaT1,t = ([A1]x[Ox])/([T1]x[T])) as well as the factor of activation (PaT1,t) and rate constants of elementary steps reactions that govern the increase of Mn with conversion in controlled cationic ring‐opening polymerization of oxetane (Ox) in 1,4‐dioxane (1,4‐D) and in tetrahydropyran (THP) (i.e. cyclic ethers which have no homopolymerizability (T)) were determined using terminal‐model kinetics. We show analytically that the dynamic behavior of the two growing species (A1 and T1) competing for the same resources (Ox and T) follows a Lotka‐Volterra model of predator‐prey interactions.

Catalytic reactions of oxetanes with protonic reagents and aprotic reagents leading to novel polymers

AbstractThis paper reports new addition reactions of oxetanes with certain protonic reagents such as carboxylic acid, phenol, and thiol, and with certain aprotic reagents such as acyl chloride, thioester, phosphonyl dichloride, silyl chloride, and chloroformate using quaternary onium salts as catalysts. The kinetic study of the addition reactions of oxetanes was also investigated. These new addition reactions were applicable to the synthesis of new polymers. These polyaddition systems could also construct both polymer main chains and reactive side chains. The alternating copolymerization of oxetanes with carboxylic anhydride was performed. Furthermore, it was found that anionic ring‐opening polymerization of oxetanes containing hydroxy groups proceeded to afford the hyperbranched polymer (HBP) with an oxetanyl group and many hydroxy groups at the ends of the polymer chains. Alkali developable photofunctional HBPs were synthesized by the polyaddition of bis(oxetane)s or tris(oxetane)s, and their patterning properties were examined, too. The photo‐induced cationic polymerization of the polymers with pendant oxetanyl groups and the thermal curing reactions of polyfunctional oxetanes (oxetane resins) were also examined to give the crosslinking materials quantitatively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 709–726, 2007

Coordinate anionic ring‐opening polymerization of oxetanes with aluminum benzyl alcoholate bis(2,6‐di‐tert‐butyl‐4‐methylphenolate)

AbstractAluminum benzyl alcoholate bis(2,6‐di‐tert‐butyl‐4‐methylphenolate) (BnOAD), which was prepared through the mixing of equimolar amounts of benzyl alcohol and methylaluminum bis(2,6‐di‐tert‐butyl‐4‐methylphenolate) (MAD), successfully polymerized four‐membered cyclic ethers in a coordinate anionic ring‐opening manner. The polymerization of 3‐(4‐bromobutoxymethyl)‐3‐methyloxetane (OxBr) with 5 mol % BnOAD proceeded slowly in toluene at 25 °C and produced sufficiently high‐molecular‐weight poly(OxBr) in a moderate yield in 24 h. The polymerization was greatly accelerated by the addition of a sterically hindered Lewis acid such as MAD, and this resulted in a nearly quantitative polymer yield within 24 h. In sharp contrast, conventional cationic polymerization with boron trifluoride etherate as a typical Lewis acid initiator produced low‐molecular‐weight poly(OxBr) along with a substantial amount of the cyclic tetramer. The polymerization of the simplest unsubstituted oxetane with BnOAD resulted in failure. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4570–4579, 2004

Synthesis and chemical modification of hyperbranched polyethers with terminal hydroxy groups by the anionic ring‐opening polymerization of 3‐alkyl‐3‐hydroxymethyl oxetanes

AbstractThe anionic ring‐opening polymerization of oxetanes containing hydroxyl groups was carried out with potassium tert‐butoxide as an initiator in the presence of 18‐crown‐6‐ether in N‐methylpyrrolidinone at 180 °C; it yielded corresponding multifunctional hyperbranched polymers: poly(3‐ethyl‐3‐hydroxymethyloxetane)s, with number‐average molecular weights of 2200–4100 in 83–95% yields, and poly(3‐methyl‐3‐hydroxymethyloxetane)s, with number‐average molecular weights of 4600–5200 in 70–95% yields. The synthesized poly(3‐ethyl‐3‐hydroxymethyloxetane)s and poly(3‐methyl‐3‐hydroxymethyloxetane)s were hyperbranched polyethers containing an oxetane moiety and many hydroxy groups at the ends. The postpolymerization of poly(3‐ethyl‐3‐hydroxymethyloxetane)s was performed in the presence of potassium tert‐butoxide and 18‐crown‐6‐ether in N‐methylpyrrolidinone at 180 °C; it yielded corresponding polymers with higher molecular weights in good yields. The cationic polymerization of poly(3‐ethyl‐3‐hydroxymethyloxetane) derivatives was carried out with boron trifluoride etherate as an initiator and was followed by alkaline hydrolysis; this yielded a new branched polymer, a poly(hyperbranched polyether), with many pendant hydroxy groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3739–3750, 2004

Controlled polymerization reaction with new catalyst: Design of metalloporphyrin-acid systems for monomer activation

Metalloporphyrin initiator coupled with an appropriate organometallic Lewis acid catalyst could make possible the first example of living anionic polymerization of oxetane. Lewis acid built-in metalloporphyrins were designed as a new highly active catalyst/initiator system. The concept of monomer activation by Lewis acid was extended to the use of appropriate protonic acid.

The Cationic Ring Opening Polymerization of Oxetane and Other Cyclic Ethers

Abstract The homopolymerization of oxetane in the presence of boron trifluoride etherate (BF3OEt2) and ethanediol (HOCH2CH2OH) as an initiator system gave polymer with a molecular weight in the range of 4000–7000. Previous work has shown that a side reaction such as the formation of cyclic oligomers, particularly tetramer often occurs in large quantities. In contrast during copolymerizations between specific combination of cyclic ethers, cyclic oligomers were found in smaller amounts and in some instances almost eliminated. The difference in behaviour between homo and copolymerization was ascribed to a change in the structure of the propagating end

Studies in ring-opening polymerization—XII. The ring-opening polymerization of oxetane to living polymers using a porphinato-aluminium catalyst

The polymerization of oxetane has been carried out with catalysts derived from the reaction of 5,10,15,20-tetraphenyl-21 H,23 H-porphine and aluminium diethyl chloride, catalysts that have been described as immortal systems. The polymerization of oxetane with this catalyst leads to a polymerization that is slower than the corresponding polymerization of oxirane but high conversions of monomer to polymer occur and the polymerization shows the properties of a living polymerization; the molecular weight average of the polymer increases with conversion of the monomer to polymer closely correlating with the ratio of monomer polymerized to initiator used and NMR spectra show the presence of the porphinato and other end groups.

Electroinitiated Polymerization of 3,3-BIS(N-Carbazolylmethyl)Oxetane

Abstract 3,3-Bis(N-carbazolylmethyl)oxetane, a cyclic compound with carbazolyl substituents closely linked to the oxetane ring, was polymerized by electrochemical initiation in aprotic polar solvents using a quaternary ammonium salt as electrolyte. Colored polymers were obtained as thin films deposited on the anode and were characterized by IR, 1H NMR, and thermogravimetry. The data obtained refute the classical cationic polymerization of oxetanes.

Ring‐opening polymerization of oxetanes by cationic initiators: Polymerization of 3‐azidomethyl‐ 3 ‐ methyloxetane with bis(chlorodimethylsilyl)benzene/silver hexafluoroantimonate initiating system

AbstractQuasi‐living cationic polymerization of 3‐azidomethyl‐3‐methyloxetane (AMMO) was achieved with a bis(chlorodimethylsilyl)benzene/silver hexafluoroantimonate (BSB/AgSbF6) initiating system in methylene chloride at −78°C. The average molecular weight (Mn) increased linearly with an increasing monomer/ initiator ([M]/[I]) ratio and a linear Mn vs. [M]/[I] ratio plot passes through the origin. Mn's observed were higher than the calculated value. This indicates the initial loss of initiator or slow initiation during the polymerization of AMMO with BSB/AgSbF6 initiating system, or the combination of both. Theoretically, in a system where the initiation is slower than the propagation, a diblock copolymer will be formed. Similarly, impurities, such as water, will cause chain transfer to the propagating chains during polymerization and form a homopolymer and a diblock copolymer in addition to the desired triblock copolymer. In short, a perfect triblock copolymer will be formed for a difunctional cationic initiator when the system is pure and dry and the initiation of polymerization is faster than the propagation.

Polymerization of Oxetanes with Organoaluminium Catalysts. I. Kinetics of the Polymerization of 3-Methyl-3-chloromethyloxetane with the i-Bu3Al–H2O Catalyst System

The kinetics of the polymerization of 3-methyl-3-chloromethyloxetane with the i-Bu3Al–H2O catalyst system and the molecular-weight characteristics of the resulting polymer have been investigated. The main feature of this process is the ability for self-regulation of the size of the macromolecules with the formation of a polymer of high molecular weight (∼106) and narrow molecular-weight distribution (Mw/Mn=1.30±0.05) which do not depend on conversion and initial monomer and catalyst concentrations. A kinetic scheme for the polymerization involves a slow initiation stage, rapid propagation via the preliminary stage of monomer complexation with active centres, spontaneous monomolecular termination as a result of intramolecular interaction of the active centre with a fragment of its own polymer chain and the inhibition stage due to the deactivation of the unconsumed catalyst by the polymer. The mathematical description of this scheme enabled us to calculate the rate constants for elementary reactions of the process at 20°C: the propagation-rate constant is (1.9±0.3)×103 min−1; the initiation-rate constant is (6.9±0.3)×104 l mol−1 min−1 and the termination-rate constant is (0.16±0.02) min−1.

Polymerization of Oxetanes with Organoaluminium Catalysts. II. Analysis of Molecular-Weight Distributions in the Polymerization of 3-Methyl-3-chloromethyloxetane with the Al(i-C4H9)3–H2O Catalyst System

Molecular-weight distributions and polydispersity parameters of the polymers formed in the polymerization of 3-methyl-3-chloromethyloxetane with the Al(i-C4H9)3–H2O catalyst system have been investigated. It was shown that the main feature of this process is the ability of macromolecules to regulate their own size in the formation of a polymer of high molecular weight (∼106) and narrow molecular-weight distribution (Mw/Mn=1.30±0.05) without any dependence on conversion, and the initial monomer and catalyst concentrations. Proceeding from the suggestion that the ratio of the termination to propagation-rate constants (kt/kp) depends on the size of the macromolecules, equations for the unnormalized weight molecular-weight distribution (MWD), and polydispersity parameters were derived. The experimental and calculated values of weight MWD and polydispersity parameters are in satisfactory agreement. On the basis of these data, a model for polymerization is proposed, assuming the formation of an active centre in the form of an ion-pair of the polymer zwitter-ion solvated by its own polymer chain. This model explains adequately the dependence of the kt/kp ratio on the degree of polymerization and the observed molecular-weight characteristics of the polymer.

Cyclic oligomers in the cationic polymerization of 3,3‐dimethyloxetane

AbstractThe formation of cyclic oligomers in the cationic polymerization of 3,3‐dimethyloxetane (1) was investigated. By means of gas chromatography coupled with mass spectroscopy, cyclic oligomers from tetramer up to nonamer (2a–f) were detected in decreasing concentration. The oligomer/polymer ratio at complete monomer consumption changes with the initiating system used. This ratio is not influenced by the initiator concentration but it increases with decreasing monomer concentration. It is proposed that the cyclic oligomers are formed by reaction of the monomer with macrocyclic oxonium ions of type 5 which in turn are formed by an intramolecular (temporary) termination reaction. The high preference to form cyclic tetramer is discussed in terms of the preferred polymer backbone conformation. In the polymerization of oxetane, cyclic tetramer is the most important oligomer, but, contrarily with previous reports, higher oligomers were also found to be present.

The polymerization of oxetane with hexafluorophosphate salts

Oxetane has been polymerized using both triethyloxonium hexafluorophosphate and triphenylmethyl hexafluorophosphate as initiators at −30 °C. The former gives a slow polymerization with a slow initiation process. The latter gives a rapid initiation and rapid initial polymerization which may slow down to rates similar to those found for the former initiator. The results are interpreted in terms of the formation of two types of tertiary oxonium ions. One type incorporates the oxetane molecule and is suggested to have a very rapid reaction with more oxetane. The second type does not involve the oxetane molecule but an ether linkage, such as in the polymer chain, and reacts only slowly with oxetane.

A possibility of anionic polymerization of oxetane by a coordination mechanism

A possibility of anionic polymerization of oxetane by a coordination mechanism

Solid‐state polymerization of oxetanes. II. Investigation of the growth of the polymer phase as related to the mechanism of polymerization

AbstractThe radiation‐induced solid‐state polymerization of 3,3‐bischloromethyloxetane (BCMO) was investigated by direct observation of the development of the morphology of the growing polymer phase in single crystals of the monomer. Electron microscopy shows that the polymerization gives rise to amorphous polymer in the first step. The polymer forms irregular platelets which aggregate into larger units without reflecting the crystalline order of the monomer. Subsequent to polymerization, the amorphous polymer crystallizes to the β‐modification of poly‐BCMO. If the partially polymerized crystals are extracted by solvents of the monomer, crystallization of the polymer is enhanced, and morphological artifacts arise which were previously mistaken for the true morphology of the “as polymerized” polymer. The copolymerization behavior of solid solutions of 3‐ethyl‐3‐chloromethyloxetane (ECMO) and BCMO does not differ from the liquid bulk copolymerization with respect to copolymer composition, which is different from the composition of the monomer mixture. It is concluded that the polymer chains grow in noncrystalline zones as in a polymerization in the liquid state by which amorphous polymer is formed. No lattice control was observable in this solid‐state polymerization.