Thermal degradation of poly(alkyl acrylates). II. Primary esters: Ethyl,n-propyl,n-butyl,and 2-ethylhexyl

Quantitative analyses of the products of thermal degradation of poly(ethyl acrylate), poly(n-propyl acrylate), poly(n-butyl acrylate) and poly(2-ethylhexyl acrylate) have been made, principally by the combined application of GLC and mass and infrared spectroscopy. Data are recorded in mass balance tables. The major gaseous products are carbon dioxide and the olefin corresponding to the ester group. The minor gaseous products include the corresponding alkane, the alkane/olefin ratio being of the order of 10^?2–10^?3, and traces of carbon monoxide and hydrogen. The alcohol corresponding to the alkyl group is the major liquid product but there are also traces of monomer and the corresponding methacrylate. Alcohol production exhibits autocatalytic properties. The chain fragment fractions of the products are colored yellow and have average chain lengths of 3.2, 3.3, 3.6, and 5.6 for the ethyl, n-propyl, n-butyl and 2-ethylhexyl esters, respectively. The infrared spectra are similar to those of the parent polymers but with well defined differences. Insolubility develops in the ethyl, n-propyl, and n-butyl esters, but the residual material from poly(2-ethylhexyl acrylate) remains soluble even at very advanced stages of degradation. All of these products and reaction characteristics are accounted for in terms of radical reactions with a unique initiation step.     

Stereoregularity of radically polymerized poly(alkyl acrylates) and poly(trimethylsilyl acrylates) and the preparation of syndiotactic poly(methyl acrylate)

Nuclear magnetic resonance (NMR) spectroscopy was used to determine the stereoregularity of radically polymerized poly(ethyl acrylates), poly(trimethylsilyl acrylates), and poly(isopropyl acrylate-α,β-d₂). The ethyl acrylate polymers consisted of a random configuration having about 50% of isotactic diads, and their stereoregularities were independent of the polymerization temperature (40 to ?78°C). Poly(trimethylsilyl acrylates) and poly(isopropyl acrylate-α,β-d₂) prepared at low temperatures had a syndiotactic configuration. Syndiotactic poly(methyl acrylate) was derived from syndiotactic poly(trimethylsilyl acrylate). For poly(methyl acrylate), an approximate estimation of the stereoregularity by infrared spectroscopy was proposed.     

Stereoregularity of poly(methyl acrylate)

The stereoregularity of poly(methyl acrylate) and poly(methyl acrylate-αd) was determined from the NMR spectra. A method of quantitative determination of stereoregularity of poly(methyl acrylate) proposed in this paper is based on the fact that in the 100 Mc./sec. NMR spectrum the absorption peaks due to methylene protons in syndiotactic configurations overlap absorptions due to only one of two methylene protons in isotactic configurations. The stereostructure of poly(methy1 acrylates) polymerized with anionic catalysts such as Grignard reagents, n-butyllithium, and LiAlH₄ is generally richer in isotactic diads than in syndiotactic diads. For example, poly(methyl acrylate) polymerized with phenylmagnesium bromide as catalyst at ?20°C. consists of 99% isotactic and 1% syndiotactic diads. In radical polymerization, the isotacticity of poly(methyl acrylate) is independent of polymerization temperature. Poly(methyl acrylates) polymerized with a Ziegler-Natta catalyst consisting of Al(C₂H₅)₂Cl and VCl₄ have configurations similar to those polymerized by radical initiators. The stereoregularity of poly(methyl acrylate-α-d) resembled that of poly(methyl acrylate) polymerized under the same conditions.     

Miscibility of Halogen-containing Polymethacrylates with Various Poly(alkyl acrylate)s

The miscibility behavior of a series of halogen-containing polymethacrylates with poly(methyl acrylate), poly(ethyl acrylate), poly(n-propyl acrylate) and poly(n-butyl acrylate) was investigated by differential scanning calorimetry and for lower critical solution temperature (LCST) behavior. Poly(chloromethyl methacrylate), poly(1-chloroethyl methacrylate), poly(2-chloroethyl methacrylate), poly(2,2-dichloroethyl methacrylate), poly(2,2,2-trichloroethyl methacrylate), poly(2-fluoroethyl methacrylate) and poly(1,3-difluoroisopropyl methacrylate) are miscible with some of the poly(alkyl acrylate)s. Most of the miscible blends show LCST behavior. However, poly(3-choloropropyl methacrylate), poly(3-fluoropropyl methacrylate), poly(4-fluorobutyl methacrylate), poly(1,1,1,3,3,3-hexafluoroisopropyl methacrylate), poly(2-bromoethyl methacrylate) and poly(2-iodoethyl methacrylate) are immiscible with any of the poly(alkyl acrylate)s studied. © 1997 John Wiley & Sons, Ltd.     

New initiator system for the anionic polymerization of (meth)acrylates in toluene. IV. Random copolymerization of (meth)acrylates in toluene initiated by s-BuLi ligated by lithium silanolates

Copolymerization of binary mixtures of alkyl (meth)acrylates has been initiated in toluene by a mixed complex of lithium silanolate  (s-BuMe₂SiOLi) and s-BuLi (molar ratio > 21) formed in situ by reaction of s-BuLi with hexamethylcyclotrisiloxane (D₃). Fully acrylate and methacrylate copolymers, i.e., poly(methyl acrylate-co-n-butyl acrylate), poly(methyl methacrylate-co-ethyl methacrylate), poly(methyl methacrylate-co-n-butyl methacrylate), poly(methyl methacrylate-co-n-butyl methacrylate), poly(isobornyl methacrylate-co-n-butyl methacrylate), poly(isobornyl methacrylate-co-n-butyl methacrylate) of a rather narrow molecular weight distribution have been synthesized. However, copolymerization of alkyl acrylate and methyl methacrylate pairs has completely failed, leading to the selective formation of homopoly(acrylate). As result of the isotactic stereoregulation of the alkyl methacrylate polymerization by the s-BuLi/s-BuMe₂SiOLi initiator, highly isotactic random and block copolymers of (alkyl) methacrylates have been prepared and their thermal behavior analyzed. The structure of isotactic poly(ethyl methacrylate-co-methyl methacrylate) copolymers has been analyzed in more detail by Nuclear Magnetic Resonance (NMR). © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2525–2535, 1999     

Thermal degradation of poly(alkyl acrylates). I. Preliminary investigations

A qualitative survey of the thermal degradation reactions which occur in poly(ethyl acrylate), poly(n-propyl acrylate), poly(isopropyl acrylate), poly(n-butyl acrylate) and poly(2-ethylhexyl acrylate) has been made by using three thermal analytical methods: thermogravimetric analysis (TGA), thermal volatilization analysis (TVA), and the dynamic molecular still (DMS), all combined with infrared and mass spectrometry. Degradation in poly(isopropyl acrylate), which is a secondary ester, becomes discernible at 260°C and proceeds in two stages. The other four polymers, which are all primary esters, are more stable. They degrade in a single-stage process starting at 300°C. The principal volatile products from the primary esters are carbon dioxide and the olefin and alcohol corresponding to the alkyl group. A roughly equivalent quantity of short-chain fragments is also formed. From poly(isopropyl acrylate), carbon dioxide and propylene are the only volatile products in the first phase of the reaction.     

Dynamic mechanical behavior of lightly crosslinked networks of poly(n-butyl methacrylate) and poly(n-butyl acrylate) in the rubberlike region

An investigation was made of the dynamic mechanical behavior in the rubberlike region of poly(n-butyl methacrylate) (PBuMA) and poly(n-butyl acrylate) (PBuA) networks lightly crosslinked with ethylene dimethacrylate to concentrations from 10^?6 to 10^?4 mole/cm³. The measurements were carried out by use of an apparatus for low-frequency forced vibrations working in the frequency range 2.5 × 10^?4 to 1 Hz. With parameters c₁ and c₂ of the Williams-Landel-Ferry equation, obtained from data in the main transition region, the data did not reduce in the rubberlike region for the poly(butyl methacrylate) networks; the spread of the deviations decreases with increasing concentration of the crosslinking agent. Superposition could be achieved in all cases when a shift factor was used on the vertical axis. At sufficiently low reduced frequencies and at high temperatures the storage compliance decreases in both series of polymers with increasing concentration of the crosslinking agent as expected. At higher reduced frequencies and at higher temperatures of measurement, however, anomalous behavior was observed with uncrosslinked samples having a lower compliance than those crosslinked to a very low degree. This finding was explained as due to very long relaxation times of the untrapped entanglements present in the noncrosslinked polymer, which are absent in the same polymer crosslinked already to very low degrees. The retardation spectra of both PBuMA and PBuA exhibited secondary relaxation mechanisms which were shifted by four logarithmic decades toward higher retardation times in comparison with the primary retardation maximum.     

Solution properties of poly(methyl acrylate) and (1:1) poly(styrene-co-methyl acrylate)

Poly(methyl acrylate) (PMA) and 1:1 poly(styrene-co-methyl acrylate) (PSMA) were prepared by solution and bulk polymerization, respectively. The copolymer was analyzed with NMR to ascertain its composition and microstructure. The solution properties of unfractionated PMA and fractionated PSMA in ethyl acetate were investigated by light-scattering and viscosity techniques at 35°C. Narrow composition heterogeneity as revealed from the light-scattering measurements in different solvents justified the use of a single solvent for the copolymer characterization. The equations relating the limiting viscosity number to molecular weight, the molecular dimension to molecular weight, etc., were found for homopolymer and copolymers in ethyl acetate at 35°C. In the evaluation of the Flory constant K for the unperturbed state by methods based on Flory-Fox-Schaefgen, Kurata-Stockmayer, and Stockmayer-Fixman expressions, only the first method gave a value for PMA in ethyl acetate, consistent with that obtained in other solvents, whereas similar values of K were obtained by the three methods for PSMA in ethyl acetate. The studies indicate reduced thermodynamic interaction for PSMA–ethyl acetate compared to PMA–ethyl acetate, but increased steric effect in the copolymer compared with the homopolymer.     

The copolymerization behavior of acrylate dimers: Copolymers of methyl,ethyl, and n-butyl acrylate dimers

Dimers of methyl, ethyl, and n-butyl acrylate were synthesized in good yield through the use of a phosphine catalyst. The dimers synthesized in this manner have one double bond. The activity of this double bond was investigated in copolymerization reactions with styrene. The methyl acrylate dimer proved to have a slightly more favorable reactivity ratio than either the ethyl or n-butyl acrylate dimers.     

Synthesis and crosslinking of hyperbranched poly(n‐nonyl acrylate) to form organogels

(2‐Bromo‐n‐nonan‐1‐oxycarbonyl)ethyl acrylate was synthesized as an inimer for self‐condensing vinyl polymerization (SCVP) to produce hyperbranched poly(n‐nonyl acrylate), either as a homopolymer or as a copolymer with n‐nonyl acrylate. The inimer was homopolymerized and copolymerized by atom transfer radical polymerization (ATRP) and activator generated by electron transfer ATRP to produce soluble polymers with broad polydispersities (up to ? = 9.91), which is characteristic of hyperbranched polymers produced by SCVP. The resulting hyperbranched (co)polymers were crosslinked by atom transfer radical coupling in both one‐pot and two‐step procedures. The radical–radical crosslinking reaction is extremely efficient, resulting in hard plastic particles from the homopolymer of (2‐bromo‐n‐nonan‐1‐oxycarbonyl)ethyl acrylate synthesized in bulk. Crosslinked organogels that swell in tetrahydrofuran were formed when the rate of crosslinking decreased using acetonitrile solutions. Dynamic shear and stress relaxation experiments demonstrated that the dry network behaves as a covalently crosslinked soft gel, with a glass transition at ?50 °C according to differential scanning calorimetry. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2399–2410     

Synthesis and characterization of poly (n-butyl acrylate)-poly (methyl methacrylate) latex interpenetrating polymer networks by radiation-induced seeded emulsion polymerization

A series of latex interpenetrating polymer networks (LIPNs) were prepared via a two-stage emulsion polymerization of methyl methacrylate (MMA) or mixture of MMA and n-butyl acrylate (n-BA) on crosslinked poly(n-butyl acrylate)(PBA) seed latex using ⁶⁰Co γ-ray radiation. The particles of resultant latex were produced with diameters between 150 and 250 nm. FTIR spectra identified the formation of crosslinked copolymers of PMMA or P(MMA-co-BA). Dynamic light scattering (DLS) showed that with increasing n-BA concentration in second-stage monomers, the particle size of LIPN increased. Transmission electron microscope(TEM) photographs showed that the morphology of resultant acrylate interpenetrating polymer network (IPN) latex varied from the distinct core-shell structure to homogenous particle structure with the increase of n-BA concentration, and the morphology was mainly controlled by the miscibility between crosslinked PBA seed and second-stage copolymers and polarity of P(MMA-co-BA)copolymers. In addition, differential scanning calorimeter (DSC) measurements indicated the existence of reinforced miscibility between PBA seed and P(MMA-co-BA)copolymer in prepared LIPNs.     

Characteristic ratio of poly(tetrahydrofurfuryl acrylate) and poly(2-ethylbutyl acrylate)

The synthesis, characteristic ratio C_∞ and glass transition temperature (T_g) of poly(tetrahydrofurfuryl acrylate) (PTHFA) and of poly(2-ethylbutyl acrylate) (P2EBA) are reported. P2EBA has slightly lower flexibility (C_∞ = 9.2) than PTHFA (C_∞ = 8.6), mainly because of the higher bulkiness of its side group and the closer proximity to the main chain. The C_∞ results compared with the corresponding polymethacrylates show an increase in flexibility due to the absence of the α-methyl group. Comparison with poly(methyl acrylate) clearly shows the influence of the bulkiness of the side group on the chain flexibility. The lower T_g of P2EBA than that of PTHFA may be explained by the higher flexibility of the 2-ethylbutyl side group. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1589–1592, 1997     

Copolymerization behavior of 2-vinylbenzofuran: Copolymers of ethyl acrylate,n-butyl acrylate,and methyl methacrylate

The reactivity of 2-vinylbenzofuran in copolymerization reactions with n-butyl acrylate, ethyl acrylate, and methyl methacrylate was investigated. The vinylbenzofuran was found to be a very reactive monomer with the growing chain preferring to react with this monomer no matter what its terminus. Reactivity ratios were calculated using a nonlinear least squares error-in-variables method, which gives more reliable values of r₁ and r₂.     

Phase equilibrium of poly(n-butyl acrylate) and E7

The experimental equilibrium phase diagram of mixtures of linear poly(n-butyl acrylate) of molecular mass M_w = 112000 g mol^-1 and the low molecular mass LC mixture E7 has been established using polarized optical microscopy and light scattering techniques. The diagram is found to be reminiscent of an upper critical solution temperature system. Two independent series of samples with the same composition were studied, yielding consistent results. A region of nematic and isotropic coexisting phases and a region of a single isotropic phase were identified in the composition-temperature phase diagram. The results were analysed within a theoretical model combining the Flory-Huggins lattice theory for isotropic mixing and the Maier-Saupe theory for nematic ordering. Interestingly, no region of isotropic coexisting phases was observed in our experiments. This is probably due to the fact that the nematic interaction overwhelms the isotropic interaction in the region where (I + I) coexisting phases could appear. A preferential solubility of certain constituents of the LC mixture in the polymer could possibly be a reason for this behaviour.     

Side-chain crystallinity. III. Influence of side-chain crystallinity on the glass transition temperatures of selected copolymers incorporating n-octadecyl acrylate or vinyl stearate

The influence of side-chain crystallinity on the glass transition temperatures of selected copolymers was investigated. The copolymers were selected, in part, from those whose crystallinity was treated in the preceding paper. These included the lower amorphous acrylate esters, such as methyl, ethyl, n-butyl, and 2-ethylhexyl acrylates, together with methyl methacrylate and acrylonitrile, each copolymerized with n-octadecyl acrylate over the range of composition. The decline in the glass transition temperature was linear with increasing weight fraction of n-octadecyl acrylate for all systems in the composition range where the copolymers were essentially amorphous. The extrapolated T_g for the amorphous state of poly(n-octadecyl acrylate), and for amorphous poly(oleyl acrylate), was close to ?111°C. This coincided with a value previously obtained by an extrapolation of data on homologs. Beyond a critical fraction of octadecyl acrylate (0.3 to 0.5), developing side-chain crystallinity in n-octadecyl acrylate raised the glass temperature steadily for all systems, up to a value of 17-C, obtained for the crystalline homopolymer. Crystallinity did not develop in stiff copolymers until T_g was about 30°C below the melting point of the most perfect crystals. In compositionally heterogeneous copolymers incorporating vinyl stearate, blocks of crystalline units appeared to be dispersed in a glassy matrix of amorphous co-units. An empirical equation was derived which fitted the experimental data for random copolymers, over all composition ranges, with fair accuracy.     

Organotin polymers—II.Copolymerization parameters for tributyltin methacrylate with methyl acrylate,ethyl acrylate,butyl acrylate and acrylonitrile

Copolymerizations of tributyltin methacrylate (M₁) with methyl acrylate, ethyl acrylate, n-butyl acrylate and acrylonitrile were carried out in solution at 70° using azobisisobutyronitrile as initiator. Copolymer compositions were determined by tin analysis; monomer reactivity ratios were calculated by Fineman-Ross and Kelen-Tüdös methods. The reactivities of acrylic esters decrease as the alkyl group becomes bulkier. Azeotropic copolymers could be formed from tributyltin methacrylate with butyl acrylate and with acrylonitrile. The structures of M₁ and its azeotropic copolymers have been investigated by infrared spectroscopy.     

Stereoregularity of poly(isopropyl acrylate) and its racemization during hydrolysis

The diad tacticity of poly(isopropyl acrylate) was measured from the β-proton absorptions of poly(isopropyl acrylate-α,β-d₂) obtained with a 100 MHz NMR spectrometer, and temperature dependence of the tacticity of the polymers obtained by radical polymerization was determined. Enthalpy and entropy differences between isotactic and syndiotactic addition for poly(isopropyl acrylate) were calculated to give the following values: Δ(ΔS) = 0.7 eu; Δ(ΔH) = 0.51 kcal/mole. In the hydrolysis of poly(isopropyl acrylate-α,β-d₂), it was found that the rate of hydrolysis of poly(isopropyl acrylate) was dependent on the molecular weight rather than on the tacticity. As for the rate of racemization during hydrolysis, the rate for syndiotactic polymer was much faster than that for the isotactic polymer. The exchange reaction of deuterium at α-position with hydrogen occurred in all the polymers during hydrolysis reaction.     

A redox-initiated xylan–poly(sodium acrylate) graft copolymer

An aspen 4-O-methylglucuronoxylan was grafted with poly(sodium acrylate) (PSA) in 3.4N NaOH at 25–30°C. with the use of a persulfate–thiosulfate redox initiator system. The formation of a true graft copolymer was indicated by fractional precipitation and light-scattering studies, physical mixtures of the two pure polymers being used as references. A grafted fraction was isolated, containing no ungrafted xylan but possibly some PSA homopolymer, which contained 96.5% PSA and 3.5% xylan, or an average of 3.2 PSA chains of M?_n approximately 90,500 per xylan chain of M?_n approximately 10,500.     

Dynamic relaxation behavior of copolymers of n-butyl methacrylate with n-butyl acrylate and of 2-hydroxyethyl methacrylate with ethyl acrylate,n-butyl acrylate,and dodecyl methacrylate

The effect of the α-methyl group on the mobility of the main and side chains of methacrylateacrylate copolymers has been investigated. Poly(ethyl acrylate) shows a small secondary loss maximum (attributed to the rotation of ? COOR side chains) at 145 K, while in the case of poly(n-butyl acrylate) this relaxation process is smeared out or possibly absent. On the contrary, poly(n-butyl methacrylate) and poly(2-hydroxyethyl methacrylate) exhibit secondary relaxations at about 278 and 301 K, respectively. From the dynamic mechanical response spectra of methacrylate-acrylate copolymers one can see that the removal of the α-methyl group causes a qualitative change in the molecular mechanism of the secondary relaxation, presumably as a consequence of the different participation of the main chains. The existing data, however, are insufficient to quantify these differences. The low-temperature relaxation attributed to internal motion within the side groups is not distinctly affected by the presence of α-methyl groups. If both components of the copolymer display the low-temperature relaxation (above 77 K), the loss maxima preserve their identity to a large extent. The effect of copolymer composition on the main (glass) transition temperature has been described by means of a one-parameter equation.     

Miscible blends of amorphous polymers

Thirty-five polymethacrylate/chlorinated polymer blends were investigated by differential scanning calorimetry. Poly(ethyl), poly(n-propyl), poly(n-butyl), and poly(n-amyl methacrylate)s were found to be miscible with poly(vinyl chloride) (PVC), chlorinated PVC, and Saran, but immiscible with a chlorinated polyethylene containing 48% chlorine. Poly(methyl) (PMMA), poly(n-hexyl) (PHMA), and poly(n-lauryl methacrylate)s were found to be immiscible with the same chlorinated polymers, except the PMMA/PVC, PMMA/Saran, and PHMA/Saran blends, which were miscible. A high chlorine content of the chlorinated polymer and an optimum CH₂/COO ratio of the polymethacrylate are required to obtain miscibility. However, poly(methyl), poly(ethyl), poly(n-butyl), and poly(n-octadecyl acrylate)s were found to be immiscible with the same chlorinated polymers, except with Saran, indicating a much greater miscibility of the polymethacrylates with the chlorinated polymers as compared with the polyacrylates.