Bulky Methacrylate Research Articles

Synthesis of methacrylic acid-acrylonitrile alternating copolymer using an extremely bulky methacrylate and the sequence-dependent thermal reaction behaviors

In this work, we achieved the synthesis of the alternating copolymer composed of commodity monomer units, methacrylic acid (MAA) and acrylonitrile (AN), by using a bulky and transformable methacrylate carrying 2-ethylfenchyl ester group (EFMA). The low propensity of EFMA in radical homopolymerization and the high reactivity of AN radical to methacrylate monomer in radical copolymerization allowed the peculiar alternating propagation, which was supported by the low reactivity ratios [r1 = 0.03, r2 = 0.23 for EFMA (M1) and AN (M2)]. The resultant EFMA-AN alternating copolymer was quantitatively transformed into the MAA-AN counterpart via acidolysis, as supported by 1H and 13C NMR analyses in comparison with the corresponding 1:1 statistical copolymer. The MAA-AN alternating copolymer underwent thermal reaction between neighboring pendant groups in alternating sequence, which was different from the statistical copolymer composed of various sequence patterns.

A Transformable and Bulky Methacrylate Monomer That Enables the Synthesis of an MMA-nBA Alternating Copolymer: Sequence-Dependent Self-Healing Properties.

In this study, we designed a methacrylate molecule with an alkyl-substituted trichloro salicylic acid pendant as a transformable bulky monomer to enable the synthesis of an alternating copolymer of methyl methacrylate (MMA) and n-butyl acrylate (nBA). The adamantyl-substituted methacrylate monomer (1-Ad) showed very low homopolymerization propensity in radical polymerizations, but afforded the alternating copolymer with nBA via copolymerization. The 1-Ad units in the resultant copolymer were quantitatively and selectively transformed into MMA via transesterification with methanol to yield the alternating copolymer of MMA and nBA. Its alternating sequence was clearly demonstrated by a structural analysis via 13 C NMR spectroscopy as well as the low reactivity ratios for the 1-Ad and nBA pair. Finally, we verified the superior self-healing ability of the alternating copolymer compared to that of the corresponding 1 : 1 statistical copolymer.

Stereospecific Polymerization of Bulky Methacrylates Using Organocatalyst in Strong Donating Solvent via Self-Controlled Mechanism

Stereospecific Polymerization of Bulky Methacrylates Using Organocatalyst in Strong Donating Solvent via Self-Controlled Mechanism

Asymmetric anionic polymerization of tris(trimethylsilyl)silyl methacrylate: a highly isotactic helical chiral polymer

A highly bulky methacrylate, tris(trimethylsilyl)silyl or supersilyl methacrylate, was polymerized quantitatively with 9-fluorenyllithium in the presence of (−)-sparteine as a chiral ligand in toluene at −78 °C to give insoluble polymers. The obtained polymers exhibited high isotacticity (mm>99%) and chirality, which was confirmed by diffuse reflectance circular dichroism spectroscopy. Thus, the bulky silyl methacrylate undergoes asymmetric anionic polymerization with the chiral initiating systems via formation of a prevailing one-handed helical conformation.

From-syndiotactic-to-isotactic stereogradient methacrylic polymers by RAFT copolymerization of methacrylic acid and its bulky esters

The synthesis of stereogradient polymers with tacticities that vary from predominantly syndiotactic to highly isotactic was investigated by reversible addition–fragmentation chain transfer (RAFT) copolymerization of bulky methacrylates, such as triphenylmethyl methacrylate (TrMA) and 1-phenyldibezosuberyl methacrylate (PDBSMA) and methacrylic acid (MAA) in both non-polar and polar solvents. The MAA monomer showed increased reactivity in toluene because of hydrogen bonding and was consumed slightly faster than TrMA or PDBSMA. However, the RAFT copolymerization of TrMA and MAA in 1,4-dioxane resulted in consumption of both monomers at the same rate. The copolymers can be easily converted to homopoly(MAA) by the acid hydrolysis of the bulky group and converted further to poly(methyl methacrylate) by methyl esterification using trimethylsilyldiazomethane to analyze the molecular weights and tacticity. The molecular weights of the polymers obtained in both solvents increased with monomer conversion, which indicates that controlled/living radical copolymerization proceeded irrespective of the solvents. 13C NMR analyses of the polymers revealed that stereogradient polymers were produced in toluene, in which the tacticity changed from mm = 11% to nearly 100%, whereas the copolymers obtained in 1,4-dioxane resulted in nearly atactic enchainment (rr/mr/mm ≈ 38/49/13), independent of monomer conversion. A similar stereogradient copolymer was also obtained by RAFT copolymerization of PDBSMA and MAA in toluene, where the isotacticity changed more gradually from mm = 14% to nearly 100%.

Stereogradient Polymers Formed by Controlled/Living Radical Polymerization of Bulky Methacrylate Monomers

AbstractUnter Kontrolle: Das sperrige Monomer Triphenylmethylmethacrylat (TrMA) wurde mithilfe von RAFT‐Reagentien polymerisiert (RAFT: reversibler Additions‐Fragmentierungs‐Kettentransfer). Stereogradiente Polymere, in denen die Isospezifität mit Abnahme der Monomerkonzentration spontan zunahm, entstanden in einem Polymerisations‐Depolymerisations‐Gleichgewicht, durch das ein weniger stabiles wachsendes Polymerende in eine stabilere Form überführt wird (siehe Bild).magnified image

Stereogradient Polymers Formed by Controlled/Living Radical Polymerization of Bulky Methacrylate Monomers

Life RAFT: A bulky methacrylate monomer, triphenylmethyl methacrylate (TrMA), was polymerized with reversible addition-fragmentation chain transfer (RAFT) agents. Stereogradient polymers in which the isospecificity increased spontaneously as the monomer concentration decreased were formed by a polymerization-depolymerization equilibrium that can convert a less stable growing polymer terminal into a more stable form (see picture).

Self-Organization-Induced Three-Dimensional Honeycomb Pattern in Structure-Controlled Bulky Methacrylate Polymers: Synthesis, Morphology, and Mechanism of Pore Formation

Here we report, for the first time, a novel molecular design for three-dimensional honeycomb structures through a self-organization of hydrogen-bonded bulky anchoring group in a methacrylic polymer backbone. The polymerizable monomer design includes a methacrylic double bond linked to various hydrophobic anchoring units such as ethane, n-decane, tricyclodecane (TCD), and adamantane via a hydrogen-bonded cycloaliphatic urethane linkage. The structures of the polymers were confirmed by nuclear magnetic resonance (NMR) and the molecular weights of the polymer were determined by gel permeation chromatography (GPC). The methacrylate polymers having tricyclodecane and adamantane bulky anchoring groups self-organized to produce three-dimensional honeycomb patterns in tetrahydrofuran-water solvent mixture at ambient conditions, whereas its linear analogues (ethane, n-decane) failed to produce any micropattern. The scanning electron microscopy (SEM) analysis of the above-prepared polymer films revealed that the structure of the polymer played a major role in the formation of the honeycomb patterns. The solution Fourier transform infrared (FTIR) measurements confirmed that the bulky tricyclodecane and adamantane polymers have strong hydrogen-bonding interaction compared to that of their linear analogues, which is the driving force for the micropatterns. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) analysis of the bulky polymers revealed that the polymers exist as vesicles or micelles in the solution, which leads to the formation of the honeycomb pattern. The honeycomb pattern formation in the bulky polymer systems suggests that two cooperative factors such as hydrogen-bonding interaction and hydrophobicity of bulky anchoring units are necessary to induce three-dimensional honeycomb structures. To investigate the effect of molecular weights and its distribution on the self-organization process, both benzoyl peroxide (BPO) initiated free radical and atom transfer radical polymerization (ATRP) techniques were employed for the polymerization. Micropores formed irrespective of differences in molecular weight and polydispersity index (PDI); however, the pore size distribution was influenced by both molecular weights and PDI. Low molecular weight samples afforded polydisperse pores with the ATRP samples with more narrow PDI producing pores with large dimensions. The approach has also been investigated for polystyrene-bulky methacrylic copolymer, and the results revealed that uniform honeycomb patterns were produced for copolymers having more than 50 mol % incorporation of bulky units.

Influence of the cocatalyst structure on the statistical copolymerization of methyl methacrylate with bulky methacrylates using the zirconocene complex Cp2ZrMe2

AbstractStatistical copolymers of methyl methacrylate with cyclohexyl and trimethylsilyloxy ethyl methacrylate were synthesized with two different catalytic systems based on the zirconocene complex Cp2ZrMe2. The reactivity ratios of methyl methacrylate and these methacrylates were calculated with the Finemann–Ross, inverted Finemann–Ross, and Kelen–Tüdos graphical methods. The structural parameters of these copolymers were estimated from the calculation of the dyad monomer sequence fractions. Two different borate cocatalysts were employed, and their effect on the copolymerization process is discussed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3305–3314, 2005

Polymerization of acrylates and bulky methacrylates with the use of zirconocene precursors: Block copolymers with methyl methacrylate

AbstractThe polymerization behavior of cyclohexyl methacrylate and trimethylsilyloxyethyl methacrylate with the catalytic system Cp2ZrMe2/B(C6F5)3/ZnEt2 was examined. Block copolymers of these bulky methacrylates with methyl methacrylate (MMA), having high molecular weights and relatively narrow molecular weight distributions, were prepared. n‐Butyl acrylate and tert‐butyl acrylate were polymerized with various catalytic systems based on zirconocene complexes. These polymerizations seemed to proceed to a nonquantitative yield, producing polymers with high molecular weights and relatively low polydispersities. This behavior indicated the presence of termination reactions in the initiation step, which appeared to be faster than the propagation step. Block copolymers of these acrylates with MMA were synthesized with the catalytic system rac‐Et(Ind)2ZrMe2/[B(C6F5)4]−[Me2NHPh]+/ZnEt2, starting from the polymerization of MMA. The block copolymers produced were well defined in most cases, as indicated by size exclusion chromatography, NMR, and differential scanning calorimetry measurements. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3337–3348, 2005

Asymmetric polymerization of methacrylates

The syntheses of optically active polymers having helical conformation from bulky methacrylates are reviewed focusing on selected topics. The monomers include triphenylmethyl methacrylate and its analogues. Asymmetric anionic polymerization of the monomers gives isotactic, optically active polymers having a helical structure with excess helicity. The isotactic content and the extent of helical-sense excess depend on the monomer structure and the reaction conditions. In the case of methacrylates, completely isotactic and single-handed helical polymers can be produced by asymmetric anionic polymerization (helix-sense-selective polymerization). Asymmetric radical polymerization is also possible for this class of monomer. Some of the helical polymers show chiral recognition ability toward a wide range of racemic compounds. Polymers having main-chain configurational chirality are also discussed.

Synthesis, characterization, and application of helical polymers

AbstractThis review mainly describes the asymmetric synthesis of optically active polymers with helical conformation. Bulky methacrylates such as triphenylmethyl methacrylate and 1‐phenyldibenzosuberyl methacrylate give one‐handed helical and optically active polymers with almost perfectly isotactic main chain conformation by polymerization with chiral anionic initiators. The radical polymerization and copolymerization of these monomers under chiral conditions also afford optically active polymers with prevailing one‐handed helicity. N, N‐Disubstituted acrylamides also give optically active, helical polymers in the asymmetric anionic polymerization. Optically active polyisocyanates with a prevailing one‐handed helical structure have been prepared in the copolymerization of an achiral isocyanate with a small amount of an optically active isocyanate and also in the polymerization of alkyl and aromatic isocyanates with optically active lithium alkoxide or amide compounds. The existence of a stable helical structure for polychloral has been successfully proved with the helical oligomers of chloral. One‐handed helical polyisocyanides have been prepared by helix‐sense‐selective polymerization of bulky isocyanides and also by the cyclopolymerization of a 1, 2‐diisocyanobenzene derivative with the Pd complex of a one‐handed helical oligomer.

Asymmetric and Enantiomer-Selective Polymerization of Phenyl-2-pyridyl-o-tolylmethyl Methacrylate

The enantiomer-selective (asymmetric selective or stereoelective) polymerization of a bulky racemic monomer phenyl-2-pyridyl-o-tolylmethyl methacrylate (PPyTMA) was investigated with chiral anionic initiators, the complexes of 2,3-dimethoxy-1,4-bis(dimethylamino)butane (DDB) with fluorenyllithium or N,N′-diphenylethylenediamine monolithium amide, in toluene at −78°C. (−)-Isomer was consumed preferentially over (+)-isomer when (−)-DDB was used as a chiral ligand and a highly isotactic polymer was obtained. The initiators showed no enantiomer selectivity in the polymerization of less bulky racemic methacrylates, such as 1-phenylethyl methacrylate and 1,2-diphenylethyl methacrylate which afforded atactic polymers. Enantiomer selectivity increased with conversion up to about 25%. The e.e. of the polymerized monomer at a stage of about 25% conversion was nearly 100%. This was ascribed to a rigid one-handed helical conformation of highly isotactic poly(PPyTMA) at the early stage of the polymerization. The selectivity did not decrease in the asymmetric copolymerization with tri-phenylmethyl methacrylate (TrMA), but greatly decreased in the copolymerization with the less bulky methacrylates. The former copolymerization formed a coisotactic polymer and the latter atactic copolymers.