Correlations between alkyl side chain length and dynamic mechanical properties of poly(n-alkyl acrylates) and poly(n-alkyl methacrylates)

In the present paper, dynamic mechanical properties of poly(n-alkyl acrylates) (PnAA) and poly(n-alkyl methacrylates) (PnAMA) with different alkyl side chain length were studied. The results show that with the increase of alkyl side chain length, the storage modulus changes more steadily, and the loss modulus peak and the tanδ peak become broader for PnAA and PnAMA. At the same time, the tanδ peak is more and more apart from the loss modulus peak and the point where the storage modulus begins to drop. For quantitative discussion, three variables, the steepness index (S), the transition wideness (W) of storage modulus and the integration area (A) of tanδ were defined to investigate the potential correlation between the dynamic mechanical properties and alkyl side chain length. It can be observed that S decreases while W and A increase with increasing alkyl side chain length. Moreover, the relaxation spectra of the two series of polymers are calculated from the corresponding mechanical spectra. The shapes of the relaxation spectra are broader and broader with the increase of the alkyl side chain length. These phenomena are interpreted by the perspective of fragility, molecular packing efficiency and intermolecular coupling.     

Graft copolymers of poly(methyl methacrylate) backbone and poly(propylene oxide-b-ethylene oxide) branches

Summary Two mono-functional macromonomers of poly (propylene oxide-b-ethylene oxide) were synthesized by reaction with methacryloyl chloride. The macromonomers have the same molecular weight and ratio of ethylene oxide and propylene oxide sequences. The reactive methacrylate group can be linked to the ethylene oxide (BuPPOPEO) or to the propylene oxide (BuPEOPPO). These macromonomers showed self-gelling in one week even at low temperature and under a dry atmosphere. Graft copolymers were obtained by reaction of these macromonomers with methyl methacrylate upon free-radical initiation and they were characterized by GPC, VPO, IR and ¹H NMR spectra.     

Stereocomplex formation in polybutadiene-syndiotactic poly(methyl methacrylate) block copolymers blended with isotactic poly(methyl methacrylate)

Summary The process of stereocomplexation in blends of isotactic poly(methyl methacrylate)s and polybutadiene-syndiotactic poly(methyl methacrylate) diblock copolymers was studied by differential scanning calorimetry as a function of molar mass of the constituents, annealing time and temperature. The amount of complex formed is dependent on these three parameters, while the temperature of decomposition of the complex is only dependent on the annealing temperature. Complex formation can be observed in blends containing a copolymer with a very low molar mass syndiotactic poly(methyl methacrylate) block (Mn=700). In contrast to homopolymer blends, for which two endotherms of decomposition were generally reported, only one endotherm is observed for copolymer-homopolymer blends. This behavior is attributed to the elastomer block.     

Syntheses of poly(methyl methacrylate)/poly(dimethyl siloxane) graft copolymers and their surface enrichment of their blend with acrylate adhesive copolymers

Several types of poly(methyl methacrylate)/poly(dimethyl siloxane) graft copolymers (PMMA‐g‐PDMS) were synthesized using macromonomer technology. Three types of PMMA‐g‐PDMS with different PDMS chain length were obtained. The effect of siloxane chain length on surface segregation of PMMA‐g‐PDMS/poly(2‐ethylhexyl acrylate‐co‐acrylic acid‐co‐vinyl acetate)[P(2EHA‐AA‐VAc)] blends was investigated. The blends of PMMA‐g‐PDMS with P(2EHA‐AA‐VAc) showed surface segregations of PDMS components. The surface enrichments of PDMS in the blends depended on the PDMS chain length, significantly. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1736–1740, 2002     

Effect of copolymer composition on the miscibility of blends of styrene-acrylonitrile copolymers with poly (methyl methacrylate)

The phase behaviour for blends of various polymethacrylates with styrene-acrylonitrile (SAN) copolymers has been examined as a function of the acrylonitrile content of the copolymer. Poly(methyl methacrylate), poly(ethyl methacrylate) and poly(n-propyl methacrylate) were found to be miscible with SANs over a limited window of acrylonitrile contents while no SANs appear to be miscible with poly(isopropyl methacrylate) or poly(n-butyl methacrylate). These conclusions were reached on the basis of lower critical solution temperature (LCST) and glass transition temperature behaviour. All miscible blends exhibited phase separation on heating, LCST behaviour, at temperatures which varied greatly with copolymer composition. An optimum acrylonitrile (AN) level ranging from about 10 to 14% by weight resulted in the highest temperatures for phase separation which has important implications for selection of SANs to produce homogeneous mixtures by melt processing. The basis for miscibility in these systems is evidently repulsion between styrene and acrylonitrile units in the copolymer as explained by recent models. The excess volumes for all blends are zero within experimental accuracy which suggests that the interactions for miscibility are relatively weak even for the optimum AN level. This interaction becomes smaller the larger or more bulky is the alkyl side group of the polymethacrylate.     

Miscibility of poly(methoxymethyl methacrylate) and poly(methylthiomethyl methacrylate) with poly(methyl methacrylate)

Summary Poly(n-propyl methacrylate) is known to be immiscible with poly(methyl methacrylate) (PMMA). However, we have found that poly(methoxymethyl methacrylate) is miscible with PMMA, indicating the importance of ether oxygen atoms in achieving miscibility. On the other hand, poly(methylthiomethyl methacrylate) is immiscible with PMMA.     

Solution behavior of graft copolymers of poly(methyl methacrylate) backbone and poly(propylene oxide-b-ethylene oxide) branches: effect of structure and composition

Summary The effect of structure and composition of poly(methyl methacrylate) (PMMA) main chain and poly(propylene oxide-b-ethylene oxide) (PPO-b-PEO) graft chain on solution behavior was evaluated. Separated samples of homopolymers were also analysed to provide comparisons. The solutions were prepared by dissolving the sample in selective mixtures of tetrahydrofuran (THF) and hexane. The polymer solutions were submitted to viscometric measurements as function of the solvent composition. The ratio of ethylene oxide/propylene oxide (EO/PO) units determines the modification in molecular conformation of the (PPO-b-PEO) block copolymers as function of the solvent composition. The macromolecular structure is the most important factor on the graft copolymers behavior. The structure in which ethylene oxide is linked to the main chain provides higher interaction between graft copolymers and solvent (THF/hexane).     

Preparations and oil absorptivities of poly(stearyl methacrylate-co-cinnamoyloxyethyl methacrylate) and PET nonwoven fiber photocrosslinked with it

Cinnamoyloxyethyl methacrylate (CEMA) was synthesized by the reaction of cinnamoyl chloride (CMC) and 2-hydroxyethyl methacrylate (HEMA). Its copolymers with stearyl methacrylate (SMA) were synthesized using benzoyl peroxide (BPO) as an initiator. The synthesized copolymers, poly(SMA-co-CEMA)s (PSCMAs), were photocrosslinked by UV light irradiation. The structures of the products were confirmed by IR and NMR spectroscopies. The thermal properties of the synthesized polymers were determined by DSC. The crystalline melting temperature of crosslinked PSCMA was decreased with increasing CEMA content in the feed. The oil absorptivities of the synthesized polymers were evaluated by the ASTM method (F726-81). The highest oil absorptivity of crosslinked PSCMA on poly(ethylene terephthalate) (PET) nonwoven fiber (NWF) was 610% in 10% crude oil diluted with toluene when the mol percentage of CEMA to SMA in the feed was 7.5. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2349–2357, 1999     

Preparation and characterization of poly(vinyl alcohol-co-methyl methacrylate) copolymers

Summary An investigation is presented of the preparation and characterization of poly(vinyl alcohol-co-methyl methacrylate) copolymers which can be used for the preparation of novel membranes. These polymers were prepared by copolymerization of vinyl acetate and methyl methacrylate by -irradiation, followed by methanolysis of the produced copolymers. IR and ¹H-NMR studies established the structure of the copolymers.On sabbatical leave from the Department of Chemical Engineering, Sung Kyun Kwan University, Suwon 170-00, Republic of Korea.     

Influence of the molecular weight of poly(methyl methacrylate) on fracture surface energy in notched tension

Specimens of poly(methyl methacrylate) (PMMA) were prepared by the radiolysis of a polymer from an initial viscosity average molecular weight of $\text{M}\text{?}{}_{\mathrm{v}}\text{= 1.1 × 10}{}^6$ down to 1.5 × 10⁴. Corresponding values of fracture surface energy, ranging from 3.5 × 10⁵ erg/cm² to 4.5 × 10² erg/cm², were calculated from tensile data using Griffith's equation. A theoretical dependence of fracture energy on molecular weight was derived on the assumption that only molecules exceeding a critical molecular weight can contribute to the work of plastic deformation. Comparison with experimental data indicates this molecular weight to be about 1 × 10⁵. Limitations of the theoretical treatment are discussed.     

Surface modification of poly(vinyl chloride) with poly(methyl methacrylate)/poly(dimethyl siloxane) graft copolymers

X-ray photoelectron spectroscopy is used to study the surface segregation of siloxane in dilute blends of poly(methyl methacrylate)/poly(dimethyl siloxane) graft copolymers in poly(vinyl chloride)(PVC). The graft copolymers are found to be extremely efficient surface modifiers, which form, when added in amounts of 0.5% or more, a continuous siloxane overlayer on the surface of PVC. © 1995 John Wiley & Sons, Inc.     

Solubility behavior of amphiphilic sulfonated copolymers based on styrene–stearyl methacrylate and styrene–stearyl cinnamate

Amphiphilic polymers have found many applications, so many types of these copolymers have been prepared. Specifically, sulfonated polystyrene acts, for example, as a flocullant or dispersant of petroleum asphaltenes as a function of its hydrophilic–hydrophobic balance. However, when changing the sulfonation degree, looking for the best performance, the solubility also changes, and sometimes it is responsible for making the polymer unsuitable for any application. Therefor, this work investigates in detail the changes in the solubility range of copolymers based on styrene–stearyl methacrylate and styrene–stearyl cinnamate with different molar compositions and different sulfonation degrees. The copolymers were synthesized and characterized by ¹H‐NMR, Fourier transform infrared spectroscopy, and elemental analysis. In the range of compositions analyzed, with increasing content of long hydrocarbon chains, not only the displacement of the solubility in solvents with lower solubility parameter (δ), but also the broadening of the solubility range was observed. In general, the solubility was directly related to the sulfonic group content, but there appeared to be an influence of the randomness of the sulfonation reactions along the chains. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43112.     

Miscibility of poly(methoxymethyl methacrylate) and poly(methylthiomethyl methacrylate) with poly(styrene-co-acrylonitrile) and poly(p-methylstyrene-co-acrylonitrile)

The miscibility of poly(methoxymethyl methacrylate) (PMOMA) and poly(methylthiomethyl methacrylate) (PMTMA) with poly(styrene-co-acrylonitrile) (SAN) and poly(p-methylstyrene-co-acrylonitrile) (pMSAN) was studied by differential scanning calorimetry. PMOMA is miscible with SAN having an acrylonitrile (AN) content around 30 wt %. However, PMOMA is immiscible with any of the pMSAN having AN contents between 9 and 36 wt % and with pMSAN having AN contents between 19 and 34 wt %. The miscibility of the blends enables the evaluation of various segmental interaction parameters.     

The critical organic modifier aliphatic tail length for the formation of poly(methyl methacrylate)-montmorillonite nanocomposites

In this article, we report the influence of organic modifier structure (alkyl chain length C8-C20, single vs ditallow) and thereby, the effect of hydrophobicity on the structure, thermal and mechanical properties of poly(methyl methacrylate) (PMMA)-clay hybrids. Melt processed PMMA-clay hybrids were characterized using wide-angle X-ray diffraction, transmission electron microscopy, and differential scanning calorimetry. The organoclays having an alkyl chain length of more than 12 CH₂ groups resulted in the formation of nanocomposites. The glass transition temperature (T_g) of PMMA increased in the presence of clay. The mean-field lattice model was used to predict the free energy for nanocomposite formation, which showed a reasonable match with the experimental results and provided a general guideline for the proper selection of polymer and organoclay (ie, organic modifier) to obtain nanocomposite. Tensile modulus showed maximum improvement of 58% for the nanocomposites compared to 9% improvement for the composites. Tensile modulus increased with increases in the alkyl chain length of the organic modifier and clay loading. The level of improvement for the tensile properties of nanocomposites prepared from primary and secondary ammonium-modified clay is the same as that obtained with the commercial organoclays.     

Miscibility of poly(methoxymethyl methacrylate) and poly(methylthiomethyl methacrylate) with poly(vinylidene fluoride)

Summary The miscibility behaviour of poly(methoxymethyl methacrylate) (PMOMA) and poly(methylthiomethyl methacrylate) (PMTMA) with poly(vinylidene fluoride) (PVDF) was examined by differential scanning calorimetry. PMOMA/PVDF blend system was judged to be miscible on the bases of the presence of a single, composition-dependent glass transition for the blend and a pronounced melting point depression of the PVDF component. Furthermore, lower critical solution temperature (LCST) behaviour was observed for all PMOMA/PVDF blends. PMTMA/PVDF blends were found to be immiscible. Based on the melting point depression of PVDF in PMOMA/PVDF blends, the interaction parameter B was found to be -14.5 J/cm³.     

Effect of tacticity of poly(methyl methacrylate) on the miscibility with poly(vinyl acetate)

The results of the miscibility between the chemically similar polymers poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) published so far show inconsistent statements concerning miscibility. The problems may be due to differences in molecular weights, tacticity, and preparation methods of the polymers. This investigation was carried out by using either chloroform or tetrahydrofuran (THF) as solvent to prepare the blends, because to our knowledge, nobody has reported any tacticity effect of PMMA on the miscibility with PVAc. Therefore, in this article, different tactic PMMAs were used to mix with PVAc and their miscibility was studied calorimetrically. The results showed little effect of solvent and tacticity. PMMA and PVAc were determined to be almost completely immiscible because of the observation of two T_g's. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 35–39, 2004     

Effect of tacticity of poly(methyl methacrylate) on the miscibility with poly(vinyl pyrrolidone)

Isotactic, atactic, and syndiotactic poly(methyl methacrylates) (PMMA) (designated iPMMA, aPMMA, and sPMMA) with approximately the same molecular weight were mixed separately with poly(vinyl pyrrolidone) (PVP) primarily in chloroform to make three polymer blend systems. Differential scanning calorimetry (DSC) was used to study the miscibility of these blends. The results showed that the tacticity of PMMA has a definite impact on its miscibility with PVP. The aPMMA/PVP and sPMMA/PVP blends were found to be miscible because all the prepared films showed composition-dependent glass-transition temperatures (T_g). The glass-transition temperatures of the aPMMA/PVP blends are equal to or lower than weight average and can be qualitatively described by the Gordon–Taylor equation. The glass-transition temperatures of the other miscible blends (i.e., sPMMA/PVP blends) are mostly higher than weight average and can be approximately fitted by the simplified Kwei equation. The iPMMA/PVP blends were found to be immiscible or partially miscible based on the observation of two glass-transition temperatures. The immiscibility is probably attributable to a stronger interaction among isotactic MMA segments because its ordination and molecular packing contribute to form a rigid domain. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3190–3197, 2001     

Well-defined poly(2-hydroxyethyl methacrylate) and its amphiphilic block copolymers via acidolysis of anionically synthesized poly(2-vinyloxyethyl methacrylate)

Summary A novel approach to a well-defined poly(2-hydroxyethyl methacrylate) [poly(HEMA)] and to its amphiphilic block copolymers was developed. The selective living anionic polymerization of the methacryloyl group of the bifunctional monomer 2-vinyloxyethyl methacrylate (VEMA) generated a functional polymer with a controlled molecular weight and a narrow molecular weight distribution (M_w/M_n= 1.05–1.09). This polymer is very stable under normal conditions. Being soluble in the common organic solvents, its characterization could be carried out easily. The unreacted vinyl groups in the side chains of the resulting polymer were further reacted with hydrochloric acid. This acidolysis changed poly(VEMA) to a well-defined poly(HEMA). In addition, the anionic block copolymerization of VEMA with styrene or methyl methacrylate also proceeded smoothly, generating the corresponding block copolymers. After acidolysis, these copolymers were turned into amphiphilic block copolymers containing a hydrophilic poly(HEMA) block. Received: 22 June 2001/Revised version: 15 August 2001/Accepted: 15 August 2001     

Preparation and properties of semifluorinated block copolymers of 2-(dimethylamino)ethyl methacrylate and fluorooctyl methacrylates

Semifluorinated block copolymers of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(fluorooctyl methacrylates) (PFOMA) were prepared using group transfer polymerisation via sequential monomer addition. Wide ranges of copolymers were obtained with good control over both molecular weight and composition by adjusting the monomers/initiator ratio. The micellar characteristics of the copolymers in water and chloroform were investigated by quasi-elastic light scattering and transmission electron microscopy. The size and morphologies of micelles were greatly influenced by copolymer composition, pH, and temperature. In addition, the solubility of copolymers and the formation of water-in-carbon dioxide (W/C) microemulsions were described in terms of the cloud points. The block copolymers exhibited the excellent ability of stabilizing W/C microemulsions.     

Shear induced crystallization of poly(L-lactide) and poly(ethylene glycol) (PLLA-PEG-PLLA) copolymers with different block length

With a constant poly(ethylene glycol) (PEG) block length while adjusting the block length of poly(L-lactide) (PLLA), two types of PLLA-PEG-PLLA copolymers were synthesized, and their crystallization under shear flow using high-temperature shear stage was investigated. Wide angle X-ray diffraction (WAXD) results show that PEG is noncrystalline due to its short chain length and confined crystallization by the presence of the PLLA microstructure. From the results calculated by Scherrer equation, the crystallite size of dynamic sample increased comparing to those of the quiescent sample. It could be concluded that the application of shear has a positive effect on the crystallization of long chain series and crystal size. Differential scanning calorimetry (DSC) measurement shows that shear reduces the double melting peak phenomenon and leads to much more uniform of the crystals.