Cyclohexyl Methacrylate Research Articles

Miscibility of polycarbonates with copolymers containing cyclohexylmethacrylate

AbstractWe prepared various copolymers containing styrene and methacrylates to examine their miscibility with polycarbonates such as bisphenol A polycarbonate (PC), dimethylpolycarbonate (DMPC), and tetramethylpolycarbonate (TMPC). Among the various copolymers examined, poly(methyl methacrylate‐co‐cyclohexylmethacrylate) [P(MMA–CHMA)] copolymers containing proper amounts of cyclohexylmethacrylate (CHMA) formed miscible blends with PC and DMPC, whereas TMPC did not form a miscible blend with P(MMA–CHMA). However, TMPC was miscible with poly(styrene‐co‐cyclohexylmethacrylate) [P(S–CHMA)] copolymers containing less than about 40 wt % CHMA, whereas PC and DMPC were always immiscible with P(S–CHMA). Miscible blends exhibited lower critical solution temperature (LCST)‐type phase behavior. Binary interaction energies were calculated from the observed phase boundaries with lattice–fluid theory combined with a binary interaction model. The quantitative interaction energy of each binary pair indicated that the phenyl ring substitution of polycarbonate with methyl groups did not lead to interactions that were favorable for miscibility with methyl methacrylate (MMA) and CHMA, but it did lead to favorable interactions with styrene. The addition of CHMA to MMA initially increased the LCST but ultimately led to immiscibility with PC and DMPC; however, addition of CHMA to styrene always decreased the LCST with TMPC. The increased LCST of PC or DMPC blends stemmed from intramolecular repulsion between MMA and CHMA, whereas the decreased LCST of TMPC/P(S–CHMA) blends with CHMA content came from negative interaction energy between styrene and CHMA. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1948–1955, 2001

Miscibility, Morphology, and Thermal Characterization of an Acrylic/Styrenic Blend System. Poly(cyclohexyl methacrylate) and Poly(α-methyl styrene)

Miscibility in binary polymer mixtures involving styrenic polymers and acrylics has been rare. Thermal analysis, optical and scanning electron microscopy were performed to reveal complete miscibility in the blend system of poly(α-methyl styrene) (PαMS) and poly(cyclohexyl methacrylate) (PCHMA). Within the wide range of molecular weight (MW) of PαMS (several thousands up to a high MW of 400000 g mol−1), all PαMS/PCHMA mixtures were found to be completely miscible, with phase separation at quite high lower-critical-solution-temperatures (LCST). The FT-IR characterization did not reveal any specific intermolecular interactions between the pairs. Miscibility in blends of styrenic polymers with acrylic polymers is rare and not commonly seen. Structural effects on the phase behavior in blends of styrenic polymer and acrylic polymers are briefly discussed.

Carbohydrate/monomer complexes in aqueous polymerizations: methylated-beta-cyclodextrin mediated aqueous polymerization of hydrophobic methacrylic monomers.

Hydrophobic methacrylic monomers were polymerized in aqueous media using methylated (1.8)-beta-cyclodextrin (MeCD) additives. Hydrophobic monomers tert-butyl methacrylate (tBuMA), cyclohexyl methacrylate (CMA), and 2-ethylhexyl methacrylate (2EHMA) were each dissolved in chloroform with MeCD. Chloroform was then evaporated to yield solid monomer/cyclodextrin complexes. Complexes were shown by 1H NMR and thermogravimetric analysis (TGA) to have molar ratios of monomer to MeCD as high as 0.72/1.00. The water-soluble complexes were readily polymerized in aqueous media using free radical initiation. During polymerization, hydrophobic methacrylic polymers precipitated and the majority of MeCD remained in solution. Poly(alkyl methacrylates) synthesized via this method exhibited number-average molecular weights ranging from 50,000 to 150,000 with polydispersities from 3.2 to 5.5 depending on monomer structure, and isolated yields were as high as 86%. Additionally, corresponding methacrylic/carbohydrate films were prepared and examined. High molecular weight poly(tBuMA), poly(CMA), and poly(2EHMA) were blended with MeCD to produce optically clear films with as high as 20 wt % MeCD. Differential scanning calorimetry (DSC) characterization indicated that the glass transition temperatures of these novel carbohydrate blends were controllable over a 20 degrees C range depending on the relative concentration of each component.

Synthesis and structure of ansa-metallocene complexes (M=ZrCl 2, TiCl 2, YCl, and LuCl) containing the bis(2-methyl-4,5,6,7-tetrahydroinden-yl)dimethylsilane ligand

The three step synthesis of 2-methyl-4,5,6,7-tetrahydro-1 H-indene from cyclohexyl methacrylate is described [(a) PPA cyclization; (b) LiAlH 4 reduction; (c) HCl dehydration]. This annelated trisubstituted cyclopentadiene was bridged selectively to form ethylene- or dimethylsilyl-bridged bis(2-methyl-4,5,6,7-tetrahydro-1 H-inden-1-yl) ligands. Metal complexes (M=ZrCl 2, TiCl 2, YCl, and LuCl) of the bis(2-methyl-4,5,6,7-tetrahydroinden-1-yl)dimethylsilane ligand were formed as meso/ dl stereoisomeric mixtures in ratios from 1:1 to 2:1 dl: meso.

Cyclodextrins in Polymer Synthesis: Free Radical Copolymerization of Methylated β-Cyclodextrin Complexes of Hydrophobic Monomers with N-Isopropylacrylamide in Aqueous Medium

Methylated β-cyclodextrin (me-β-CD) was used to form water-soluble host/guest complexes with the hydrophobic monomers n-butyl methacrylate (1), cyclohexyl methacrylate (2), isobornyl acrylate (3), isobornyl methacrylate (4), and styrene (5), respectively. The free-radical copolymerizations of the water-soluble N-isopropylacrylamide (NIPAAm) with these complexed monomers were carried out in water at different molar ratios.

Comparative study of the relaxation behaviour of acrylic polymers with flexible cyclic groups in their structure

The synthesis and radical polymerization of 1,3-dioxan-5-yl–acrylate and 1,3-dioxan-5-yl–methacrylate are described. The mechanical and dielectric relaxation spectra of poly(1,3-dioxan-5-yl–acrylate) and poly(1,3-dioxan-5-yl–methacrylate) exhibit prominent subglass absorptions, the locations of which are not affected by the rigidity of the main chain. The subglass relaxations of poly(1,3-dioxan-5-yl–acrylate) and poly(1,3-dioxan-5-yl–methacrylate) are shifted nearly 20°C toward lower temperatures with respect to those of poly(cyclohexyl acrylate) and poly(cyclohexyl methacrylate). The locations of the mechanical glass–rubber relaxations are not affected by the different nature of the rings located in the side groups. A study of the conductive contributions to the dielectric glass–rubber relaxation of poly(1,3-dioxan-5-yl–acrylate) and poly(1,3-dioxan-5-yl–methacrylate) is carried out using a theory that assumes that the dispersion displayed by the loss tan δ at high temperatures, in the frequency domain, arises from the Maxwell–Wagner–Sillars effect combined with Nernst–Planck electrodynamic effects caused by interfacial polarizations in the polymer–electrodes interface.

Lattice fluid theory in the analysis of interaction parameters and phase behaviour of blends involving copolymers of cyclohexyl methacrylate, methyl methacrylate and various styrene derivatives

The phase behaviour and interaction parameters of binary blends of copolymers involving cyclohexyl methacrylate (CHMA), methyl methacrylate (MMA) and various styrene derivatives (styrene (S), α-methylstyrene (AMS) and p-methylstyrene (PMS)) are examined using the lattice fluid theory of Sanchez and Lacombe. ‘Bare’ interaction parameters (ΔP∗ij) for various monomer unit pairs were deduced where possible from lower critical solution temperature (LCST) type phase boundaries and from a binary interaction model. The calculations reveal that values of the interaction parameters are less favourable to miscibility when PMS is employed instead of S in blends with CHMA and MMA. These data are in good agreement with the experimental results and the interaction parameters obtained are translatable from one system to another. The results are discussed in terms of interactions between monomer unit pairs, equation-of-state effects and thermodynamical properties.

Copolymer hydrogels of 2-hydroxyethyl methacrylate with n-butyl methacrylate and cyclohexyl methacrylate: synthesis, characterization and uptake of water

The bulk free radical copolymerizations of 2-hydroxyethyl methacrylate (HEMA) with n-butyl methacrylate (BMA) or cyclohexyl methacrylate (CHMA) were studied over the composition mole fraction interval of 0–1 for HEMA in the monomer feed. The 13C NMR (125 MHz) spectra of the copolymers were analysed to determine the copolymer composition and the stereochemical configuration of the copolymers. The terminal model reactivity ratios of HEMA and BMA were found to be r HEMA=1.73 and r BMA=0.65 and for HEMA and CHMA, r HEMA=1.26 and r CHMA=0.31. The BMA and CHMA homopolymers were found to be predominantly syndiotactic with isotacticity parameters of θ BB=0.18 and θ CC=0.19, respectively. The copolymers were also found to be predominantly syndiotactic, indicating a strong tendency for racemic additions of the monomers in the formation of the copolymers. The diffusion of water into cylinders of poly(HEMA-co-BMA) and poly(HEMA-co-CHMA) was studied over a range of copolymer compositions and was found to be Fickian. The diffusion coefficients of water at 37°C were determined from swelling measurements and were found to vary from 1.72×10 −11 m 2 s −1 for polyHEMA to 0.97×10 −11 m 2 s −1 for poly(HEMA-co-BMA) having a mole fraction F HEMA=0.80 and to 0.91×10 −11 m 2 s −1 for a poly(HEMA-co-CHMA) also having F HEMA=0.80. The mass of water absorbed at equilibrium relative to the mass of dry polymer varied from 58.8 for polyHEMA to 27.2% for poly(HEMA-co-BMA) having F HEMA=0.85 and to 21.3% for poly(HEMA-co-CHMA) having F HEMA=0.80.

Phase separation in random copolymers from high conversion free radical copolymerization, 3

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Effect of monomer architecture on segmental interaction parameters of binary blends involving copolymers of cyclohexyl methacrylate, methyl methacrylate and styrene derivatives

The phase behavior of binary blends of poly(cyclohexyl methacrylate-co-methyl methacrylate) (P(CHMA-co-MMA)) copolymers with poly(α-methylstyrene) (PAMS) and poly(p-methylstyrene) (PPMS) has been determined experimentally and compared to that of the P(CHMA-co-MMA)/PS system. The enthalpic and entropic parts of the segmental interaction parameter for each binary monomer pair involved have been determined from a fit of the lower critical solution temperature (LCST) behavior of these systems, with the aid of Flory-Huggins (FH) theory which incorporates temperature dependent interaction parameters. The results reveal that the strength of the interaction with the copolymer P(CHMA-co-MMA) decreases in the following order: PAMS > PS > PPMS. These differences are also illustrated in the glass transition (Tg)-composition curves of the above systems as well as in analog calorimetry results and scanning electron microscopy (SEM) studies. Good agreement is obtained when various theoretical miscibility windows for binary blends of copolymers involving CHMA, MMA and styrene derivatives are compared to experimental data. Thus it is shown that the subtle difference of monomer structures is captured to a good degree by the segmental interaction parameters derived from phase behavior.

Influence of Segmental Swelling Ratio of a Symmetric Block Copolymer on the Morphology of Melt-Mixed Immiscible Polymer Blends

We investigate droplet breakup and coalescence under shear flow for an immiscible polymer blend system in which styrene−acrylonitrile random copolymer and poly(cyclohexyl methacrylate) are the blend components, and a symmetric poly(styrene-b-methyl methacrylate) block copolymer (bcp) is utilized as a compatibilizer. The influence on the blend morphology of the ratio (Sr) between the swelling power at the interface of the bcp segment outside the droplet versus that inside the droplet is studied. We find that the balance of swelling between external and internal segments has an important influence on the ultimate blend morphology. Four zones of morphological behaviors are observed: Sr < 0.4, internal emulsification failure; 1 > Sr > 0.4, unstable emulsification; 2.5 > Sr > 1, stable emulsification; Sr > 2.5, external emulsification failure.

Marginal miscibility and solvent-dependent phase behavior in solution-blended poly(vinyl methyl ether)/poly(benzyl methacrylate)

Poly(vinyl methyl ether) (PVME) and poly(benzyl methacrylate) (PBzMA) were found to be miscible using differential scanning calorimetry (DSC), optical microscopy (OM), and infrared spectroscopy (FT-IR). Solvents and casting temperatures strongly affect the kinetics of the formation of blends and lead to different phase structures of the blends. The thermal transition behavior of the PVME/PBzMA blend suggests a marginal miscibility. Various scales of molecular aggregation might exist in the blends. According to FT-IR the intermolecular interactions are weak and not specific, which is in agreement with the glass transition behavior of the blends. Additionally, this study also shows that PVME is immiscible with any other polymethacrylate, such as poly(methyl methacrylate), poly(ethyl methacrylate), poly(propyl methacrylate), poly-(phenyl methacrylate), poly(cyclohexyl methacrylate), etc.

Composition dependence of phase instability and cloud point in solution-blended mixtures of polystyrene with poly(cyclohexyl methacrylate)

Composition dependence of phase behavior in the mixture system of polystyrene (PS) with poly(cyclohexyl methacrylate) (PCHMA) was examined in details using differential scanning calorimetry, optical and scanning electron microscopy, and infrared spectroscopy. This study shows that the `transparent' blends of PS/PCHMA with an apparent single T g, having been thought to be miscible in earlier reports, actually displayed micro-heterogeneity domains of about 100–300 Å. It is thus not appropriate to assess miscibility to the optically clear blends of PS/PCHMA; however, partial miscibility does exist. The PCHMA-rich (PCHMA>70 wt%) compositions are indeed miscible but the PS-rich compositions are only partially miscible with sub-micron discrete phase domains beyond detection limit of optical microscopy. The proximity of the T gs also prevented that the thermal transition of the micro phase domains in the PS-rich blends being resolved. The criterion of single T g commonly employed in assessing phase behavior should be used with extra precaution in cases where micro-heterogeneity exists, whose ambiguity is even compounded in cases where the T gs of the constituent polymers are close. The FT-ir result indicates that intermolecular interactions are weak or non-specific for the PCHMA-PS pair.

Phase structure and miscibility in blend of poly(4-methyl styrene) with poly(cyclohexyl methacrylate)

Thermal analysis, optical and scanning electron microscopy were performed to characterize solution-blended poly(4-methyl styrene) (P4MS)/poly(cyclohexyl methacrylate) (PCHMA) of full compositions. It is concluded that the true state of blend phase structure is miscibility with non-specific intermolecular interactions. To probe molecular interactions between the polymer pairs, FT-IR analysis was also used to assess possible evidence. The FT-IR results for the P4MS/PCHMA suggest that the intermolecular interactions between the pairs are likely non-specific and only comparable with those among the homopolymer molecules. Casting temperature did not seem to have any effect on the miscible phase structure of P4MS/PCHMA. Both optical microscopy and SEM characterization revealed that solution casting of P4MS/PCHMA at either temperature yielded equally homogeneous phase structure. The cloud point phenomenon is attributed to a thermodynamic lower critical solution temperature (LCST) but is kinetically irreversible at normally accessible time scales. The observed LCST could be made to be reversible in an appropriate environment where the molecules were given enough molecular mobility.

Free-radical propagation rate coefficients for cyclohexyl methacrylate, glycidyl methacrylate and 2-hydroxyethyl methacrylate homopolymerizations

Propagation rate coefficients (kp) for the homopolymerization of cyclohexyl methacrylate (CHMA), glycidyl methacrylate (GMA) and 2-hydroxyethyl methacrylate (HEMA) were determined by the pulsed laser polymerization (PLP)/size-exclusion chromatography (SEC) technique. Temperature was varied between −10 and 90°C and pressure up to 2500 bar. kp values for CHMA and GMA agree within the experimental accuracy of ± 20 per cent. They are by about a factor of 2.5 below kp of HEMA. The activation energies and activation volumes of kp of methacrylates studied so far, including linear and branched alkyl methacrylates, are close to each other: EA(kp) = (22 ± 2) kJ · mol−1 and ΔV≠(kp) = −(16 ± 2) cm3 · mol−1, respectively, indicating a pronounced family-type behavior.

Free-radical propagation rate coefficients for cyclohexyl methacrylate, glycidyl methacrylate and 2-hydroxyethyl methacrylate homopolymerizations

Propagation rate coefficients (k p ) for the homopolymerization of cyclohexyl methacrylate (CHMA), glycidyl methacrylate (GMA) and 2-hydroxyethyl methacrylate (HEMA) were determined by the pulsed laser polymerization (PLP)/size-exclusion chromatography (SEC) technique. Temperature was varied between -10 and 90°C and pressure up to 2500 bar. k p values for CHMA and GMA agree within the experimental accuracy of ± 20 per cent. They are by about a factor of 2.5 below k p of HEMA. The activation energies and activation volumes of k p of methacrylates studied so far, including linear and branched alkyl methacrylates, are close to each other: E A (k p ) = (22 ± 2) kJ.mol -1 and ΔV ( k p ) = - (16 ± 2) cm 3 . mol -1 , respectively, indicating a pronounced family-type behavior.

Free-radical propagation rate coefficients for cyclohexyl methacrylate, glycidyl methacrylate and 2-hydroxyethyl methacrylate homopolymerizations

Free-radical propagation rate coefficients for cyclohexyl methacrylate, glycidyl methacrylate and 2-hydroxyethyl methacrylate homopolymerizations

Comparative Studies on Sensitivity and Stability of Fiber-optic Oxygen Sensor Using Several Cladding Polymers

An attempt has been made to improve the sensitivity and stability of the polymer optical fiber (POF) sensor for continuous monitoring of gaseous oxygen. It utilizes the quenching phenomenon of cladding fluorescence. Three polymers namely, poly(cyclohexyl methacrylate) (PCMA), poly(l-menthyl methacrylate) (PMtMA) and poly(4-methyl-1-pentene), which have a relatively large oxygen permeability, were used as cladding layer doped with a sensitive dye such as a 9,10-diphenyl anthracene (DPA), on the polymer cores with 1 mm diameter. When these sensor heads were pumped using a D2-lamp, the response at the fluorescence of λ=431 nm was found to be very fast and reversible in all the cases, for oxygen concentrations ranging from 0.5% to 100%. However, the differences in fluorescence quenching rate, stability and response time were observed to be dependent upon the polymer used. In particular, the PCMA sample showed good long-term stability. These comparative studies of POF oxygen sensors seem to be useful for developing practical devices.

Molecular Structure Effects on the Secondary Relaxation and Impact Strength of a Series of Polyester Copolymer Glasses

The secondary relaxations of a series of glassy copolymers based on poly(ethylene terephthalate) (PET) and poly(1,4-cyclohexylenedimethylene terephthalate) (PCT) involve cooperative motions of the cyclohexylene rings. The cooperativity gives rise to longer range motions which create significant volume fluctuations that can facilitate macroscopic shear yielding. Comparison of the secondary loss peaks and activation energies by dynamic mechanical spectroscopy between the copolyesters and poly(cyclohexyl methacrylate) and poly(1,4-cyclohexylenedimethylene 2,5-dimethylterephthalate) indicates that the secondary relaxation of the copolyesters involve motions of the cyclohexylene ring. Dipolar rotational spin−echo 13C NMR confirmed large amplitude motions of the cyclohexylene ring faster than 10 kHz at 300 K. By examining feasible ring conformations, we conclude that transitions between chair and twist−boat conformations are possible for trans-cyclohexylene rings and cis-rings that prefer chair conformations. (Cis-rings that reside in boat conformations are more restricted.)

Cyclodextrins in polymer synthesis: free radical polymerisation of cyclodextrin complexes of cyclohexyl and phenyl methacrylate in aqueous medium

The polymerisation mechanism of 2,6-dimethyl-β-cyclodextrin (Me2-β-CD) complexes of phenyl methacrylate (1) and cyclohexyl methacrylate (2) is described. The polymerisation of the complexes 1 a and 2a was carried out in water with potassium peroxodisulfate/potassium hydrogensulfite as initiator. The unthreading of the Me2-β-CD during the polymerisation led to water-insoluble poly(phenyl methacrylate) (1b) and poly(cyclohexyl methacrylate) (2b). By comparison, analogously prepared polymers from uncomplexed monomers 1 and 2 in homogeneous organic solvent (THF) with AIBN as radical initiator showed significantly lower viscosities and were obtained in lower yields in both cases.