Thermal properties, specific interactions, and surface energies of PMMA terpolymers having high glass transition temperatures and low moisture absorptions

We have prepared a series of poly(methyl methacrylate) (PMMA)-based terpolymers that have high glass transition temperatures and low moisture absorptions by the free radical copolymerization of methyl methacrylate, methacrylamide, and styrene in dioxane. We have investigated the effects of the styrene content on the glass transition temperatures, hydrogen bonding interactions, surface energies, moisture absorption, and molecular weights of these poly(methyl methacrylate-co-methacrylamide-co-styrene) (Poly(MMA-co-MAAM-co-S)) terpolymers by differential scanning calorimetry, Fourier transform infrared and X-ray photoelectron spectroscopies, contact angle measurements, and gel permeation chromatography. The results indicate that the glass transition temperatures, hydrogen bonding strengths, surface energies, molecular weights, and the moisture absorption decreased upon increasing the PS content in most of the terpolymer systems. In addition, the moisture absorptions of some selected terpolymers decreased even through they possess higher values of T_g than pure PMMA. These selected terpolymers have the potential to replace pure PMMA in optical device applications.     

Thermal behavior and specific interaction in high glass transition temperature PMMA copolymer

A series of high glass transition temperature copolymers based on poly(methyl methacrylate) (PMMA) were prepared by free radical copolymerization of methacrylamide and methyl methacrylate monomers in dioxane solvent. The thermal properties and hydrogen-bonding interactions of these poly(methacrylamide-co-methyl methacrylate) (PMAAM-co-PMMA) copolymers with various compositions were investigated by differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, and solid-state nuclear magnetic resonance (NMR) spectroscopy. A large positive deviation in the behavior of T_g, based on the Kwei equation from DSC analyses, indicates that strong hydrogen bonding exists between these two monomer segments. The FTIR and solid-state NMR spectroscopic analyses give positive evidence for the hydrogen-bonding interaction between the carbonyl group of PMMA and the amide group of PMAAM (e.g. by displaying significant changes in chemical shifts). Furthermore, the proton spin-lattice relaxation time in the rotating frame (T_1ρ(H)) has one single value over the entire range of compositions of copolymers, and gives a value shorter than the average predicted. The proton relaxation behavior indicates the rigid nature of the copolymer.     

Design of responsive double-hydrophilic A-b-(B-co-C) diblock terpolymers with tunable thermosensitivity

Double-hydrophilic poly[(oligo(ethylene glycol) methacrylate)-co-methyl methacrylate]-b-poly(2-(diethylamino)ethyl methacrylate), P(EGMA-co-MMA)-b-PDEA, diblock terpolymers were designed and explored in aqueous media. Thanks to the thermosensitivity of the P(EGMA-co-MMA) statistical block and the pH sensitivity of the PDEA block, these terpolymers form two distinct micellar self-assemblies at different conditions of pH and temperature. The thermosensitivity of these terpolymers can be tuned by controlling the LCST of the statistical block through its monomer unit composition.     

Synthesis and characterization of suspension terpolymer of N‐cyclohexylmaleimide,methyl methacrylate,and styrene

N‐cyclohexylmaleimide (ChMI) and styrene (St) were polymerized with methyl methacrylate (MMA) at different St feed content by suspension polymerization method. The glass transition temperatures (T_g) of the terpolymers were detected by torsional braid analysis (TBA). Two transition peaks in TBA curves of the terpolymers with a high St content illustrated that these terpolymers have a heterogeneous chain structure and the phase separation occurred. The lower transition temperature, T_g1, was assigned to the random St‐MMA components, and the higher transition temperature, T_g2, was assigned to the St‐ChMI units‐rich segments. Thermogravimetric analyses (TGA) revealed that all the terpolymers showed a two‐step degradation process. The tensile strength of the terpolymers decrease with increasing St content while the impact strength tended to increase slightly. The rheological behavior of the terpolymers was also detected. The result illustrated that the terpolymers showed rheological behavior similar to that of pseudoplastic liquid. The apparent shear viscosity decreased with the increasing of St content. All terpolymers have a higher value of flow n than the poly(MMA‐co‐ChMI). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 918–922, 2006     

Comparison of hydrogen bonding interaction between PMMA/PMAA blends and PMMA-co-PMAA copolymers

A series of miscible PMMA/PMAA blends and PMMA-co-PMAA copolymers with different compositions were prepared in this study. T_gs of PMMA-co-PMAA copolymers are significantly higher than average values or from the Fox equation. The proton spin-lattice relaxation time in the rotating frame (T_1ρ^H) determined by high resolution solid state ¹³C nuclear magnetic resonance indicates single composition-dependent from all blends and copolymers, implying a good miscibility with chain dynamics on a scale of 1-2 nm. However, T_1ρ^Hs of copolymers are still smaller than those of blends, implying that degrees of homogeneity of copolymers are higher than those of blends. On the basis of Kovacs' free volume theory, the free volume of the copolymer obtained is decreased which is another indication of greater homogeneity of the copolymer than that of the corresponding blend. According to Fourier transform infrared spectroscopy analyses, the above results can be rationalized that the hydrogen bonding interaction of the copolymer is stronger than the blend.     

Interpolymer interactions and miscibility in poly(n‐butyl methacrylate‐co‐methacrylic acid)/poly(styrene‐co‐N,N‐dimethyl acrylamide) blends

The miscibility of poly(n‐butyl methacrylate‐co‐methacrylic acid) containing 18 mol % methacrylic acid (BMAM‐18) and poly(styrene‐co‐N,N‐dimethyl acrylamide) containing 17 mol % N,N‐dimethyl acrylamide (SAD‐17) was investigated with viscometry, differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. The DSC analysis showed a single glass‐transition temperature for all the blends, indicating that these copolymers were miscible over the entire composition range. The glass‐transition temperatures of these blends were higher than those calculated with the additivity rule. This was characteristic of the presence of specific interactions. The interactions between BMAM‐18 and the tertiary amide of SAD‐17 were studied with FTIR spectroscopy, which revealed that hydrogen‐bonding interactions occurred between the hydroxyl groups of BMAM‐18 and the carbonyl amide of SAD‐17. A new band characterizing these interactions appeared around 1613 cm^?1. The quantitative results showed that the fraction of the associated amide increased with an increase in the amount of the acidic BMAM‐18 copolymer. Although BMAM‐18 and SAD‐17 led to homogeneous solutions in butan‐2‐one, as the concentration of N,N‐dimethyl acrylamide increased to 32 mol % [as within the poly(styrene‐co‐N,N‐dimethyl acrylamide) containing 32 mol % N,N‐dimethyl acrylamide], complexation occurred when this latter compound was mixed with BMAM‐18 in butan‐2‐one. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2717–2724, 2006     

Blends of poly(ethylene oxide) and poly(4-vinylphenol-co-2-hydroxyethyl methacrylate): thermal analysis, morphological behaviour and specific interactions

DSC and optical microscopy were used to determine the miscibility and crystallinity of blends of poly(ethylene oxide) (PEO) with poly(4-vinylphenol-co-2-hydroxyethyl methacrylate) (PVPh-HEM). A single glass transition temperature was observed for all blends, indicating miscibility. A progressive decrease in the degree of crystallinity and in the size of the PEO spherullites is observed, as PVPh-HEM is added. FTIR was used to probe the intermolecular specific interactions of the blends and the miscibility of the blend is mainly attributed to PVPh-HEM/PEO intermolecular interactions via hydrogen bonding.     

In situ monitoring of thermal transitions in thin polymeric films via optical interferometry

A novel, low-cost, rapid, accurate, non-invasive and high throughput method based on the principles of Optical Interferometry (OPTI method) has been developed and applied for the in situ monitoring in one simple run of first (melting) and second (glass transition) order transitions as well as of the thermally induced decomposition of various thin polymeric films spin coated on flat reflective substrates (untreated silicon wafers). The new method has been applied successfully for measuring the glass transition, melting and decomposition temperatures of six commercially available polymers [poly(methyl methacrylate) (PMMA), poly(2-hydroxyethyl methacrylate), (PHEMA), poly(vinyl acetate-co-crotonic acid), (PVACA), poly(vinyl pyrrolidone) (PVP), poly(vinyl chloride-co-vinyl acetate) (PVCVA) and crystalline poly(vinylidene fluoride-co-hexafluoropropylene) (PVFHP)] of known T_gs or T_ms. The recorded interferometric signals were identified and characteristic signal patterns were qualitatively correlated to specific transitions. The monitoring of first and second order transitions in thin polymeric films is based on detectable differentiations of the total energy of a fixed wavelength laser beam incident almost vertically (angle of incidence <5°) onto a thin polymeric film spin coated on a flat reflective substrate. These differentiations are caused by film thickness and/or refractive index changes of the polymeric film both resulted from the significant change of the polymer's free volume taking place on the transitions. For film thicknesses over approx. 200-250 nm, the T_g or T_m of the polymeric films measured with the OPTI method were in excellent agreement with the corresponding values of the polymer, measured by DSC. An investigation on the trends of the T_g of PHEMA and PMMA films in a wide thickness range (30-1735 nm) was also carried out. Ultra-thin (∼30 nm) films of PMMA and PHEMA showed significant increase in their T_g values by approx. 30 °C upon comparing to their corresponding bulk T_gs. This behavior was attributed to an enhanced polymer-surface interaction through hydrogen bonding and/or to changes in the tacticity of the polymer.     

The effect of benzenesulfonamide plasticizers on the glass transition temperature of an amorphous aliphatic polyamide

The plasticizing effect of benzenesulfonamides (BSAs) on an amorphous aliphatic polyamide (AAPA) has been studied using dynamic mechanical analysis of copper‐supported spin‐coated mixtures. It follows that N‐(n‐butyl)BSA (BBSA), an amorphous liquid hydrogen bonding BSA, is fully miscible with AAPA because their mixtures are characterized by a single glass transition (T_g) throughout the compositional range. The T_g–composition dependence, however, is not linear because experimental results suggest a 20 K fall in T_g occurring around 0.65 BBSA units per amide unit, which coincides with the system shifting from a polymer‐like to a liquid‐like glass‐forming material. When considering a crystallizable hydrogen‐bonding plasticizer such as ethylBSA (EBSA), AAPA/EBSA mixtures become fully crystalline at a 1.3 EBSA unit per amide group. Nevertheless, melting point depression together with the single T_g observed throughout the compositional range on quenched (and therefore amorphous) samples confirms the miscibility of AAPA chains with the plasticizer. N,N‐DialkylBSAs, which lack the sulfonamide proton and therefore the possibility of hydrogen bonding with amide groups, quickly phase separate from AAPA, the glass transition of the latter staying mainly unaffected apart from a small (9 K) decrease at 10–15 mol% plasticizer. © 2001 Society of Chemical Industry     

Synthesis, characterization and corrosion protection property of terpolymers derived from poly(MAn-co-MMA) containing benzimidazole derivative as pendant group

In this study the potential of the terpolymer synthesized from poly(maleic anhydride-co-methyl methacrylate) and hydroxymethylbenzimidazole as corrosion protective coating for 60-40 brass was evaluated using dip coating technique. The copolymer, poly(maleic anhydride-co-methyl methacrylate) synthesized using free radical solution polymerization was reacted with different feed ratios of hydroxymethylbenzimidazole (HMBD) to obtain terpolymers containing maleic anhydride, MMA and mono benzimidazolylmethyl ester of maleic acid (MBMEMA) units. Both the copolymer and the terpolymers were characterized using FT-IR, ¹H NMR and ¹³C NMR spectroscopy. The thermal stability of the polymers was studied using thermogravimetric analysis (TGA) and the molecular weight of the polymer was analyzed using gel permeation chromatography (GPC). The effect of different concentrations of MBMEMA in the polymer for corrosion protection of brass in 3.5% NaCl solution was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy. Effective corrosion protection was obtained when the mole fraction of MBMEMA was 0.24 in the terpolymer. The surface morphology of the polymer coated specimens was studied by scanning electron microscopy (SEM). Solution analysis was used to calculate the dezincification factor.     

THERMOANALYSIS AND MECHANICAL PROPERTIES OF EMULSION COPOLYMER POLY(MMA-PMI-ST)

Terpolymers of methyl methacrylate (MMA), N-phenylmaleimide (PMI) and styrene (St) were synthesized by emulsion copolymerization. The glass transition temperatures (T_g) and the thermostability of copolymers were determined by differential scanning calorimetry (DSC) and programmed thermogravimetric analysis (TGA), respectively. The terpolymers show a considerable increase in decomposition temperature, activation energy of decomposition and T_g with increasing content of PMI. Furthermore, the Vicat softening points of the terpolymers rise with PMI content. The mechanical properties (tensile strength and impact strength) of the terpolymers decrease with increasing PMI content and increase insignificantly with increasing St content.     

Effects of thermal imidization on mechanical properties of poly(amide‐co‐imide)/multiwalled carbon nanotube composite films

In this study, experimental and numerical studies were performed to investigate the relationship among the functionalization method, weight fraction of MWCNTs, thermal imidization cycle, and mechanical properties of various PAI/MWCNT composite films. Poly(amide‐co‐imide)/multiwalled carbon nanotube composite films were prepared by solution mixing and film casting. The effects of chemical functionalization and weight fraction of multiwalled carbon nanotubes on thermal imidization and mechanical properties were investigated through experimental and numerical studies. The time needed to achieve sufficient thermal imidization was reduced with increasing multiwalled carbon nanotube content when compared with that of a pure poly(amide‐co‐imide) film because multiwalled carbon nanotubes have a higher thermal conductivity than pure poly(amide‐co‐imide) resin. Mechanical properties of pure poly(amide‐co‐imide) and poly(amide‐co‐imide)/multiwalled carbon nanotube composite films were increased with increasing imidization time and were improved significantly in the case of the composite film filled with hydrogen peroxide treated multiwalled carbon nanotubes. Both the tensile strength and strain to failure of the multiwalled carbon nanotube filled poly(amide‐co‐imide) film were increased substantially because multiwalled carbon nanotube dispersion was improved and covalent bonding was formed between multiwalled carbon nanotubes and poly(amide‐co‐imide) molecules. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of graft copolymers of methyl methacrylate and poly(n-hexyl isocyanate) macromonomers

Living poly(n-hexyl isocyanate) (PHIC) was deactivated with methacryloyl chloride to produce methacryl-terminated poly(n-hexyl isocyanate) (PHIC-MA) rodlike macromonomers. Radical copolymerization of methyl methacrylate (MMA) with PHIC-MA was performed using 2,2′-azobis(isobutyronitrile) as an initiator in benzene at 60 °C to prepare poly(methyl methacrylate)-graft-poly(n-hexyl isocyanate) (PMMA-graft-PHIC) graft copolymers. The monomer reactivity ratios of MMA (M₁) and PHIC-MA (M₂) were evaluated as r₁=11.5 and r₂=∼0, exhibiting remarkably lower reactivity of PHIC-MA macromonomer than that of common macromonomers. The resultant graft copolymers were characterized using gel permeation chromatography equipped with low-angle laser light-scattering to determine the molecular weights, and equipped with a refractive index detector and an ultraviolet light detector to estimate a PHIC weight fraction of PMMA-graft-PHIC at the ith elution volume of the GPC chromatogram. There are 2-3 PHIC grafts per PMMA molecule, and the PHIC rodlike chains might be difficult to introduce into the PMMA main chains having higher molecular weights. A specific dimension of PMMA-graft-PHIC in solution was discussed in detail.     

Monodispersed thermoresponsive hydrogel microspheres with a volume phase transition driven by hydrogen bonding

We report the synthesis and characterization of monodispersed thermoresponsive hydrogel microspheres with a volume phase transition driven by hydrogen bonding. The prepared microspheres, composed of poly(acrylamide-co-styrene) (poly(AAM-co-St)) cores and poly(acrylamide)/poly(acrylic acid) (PAAM/PAAC) based interpenetrating polymer network (IPN) shells, were featured with high monodispersity and positively thermoresponsive volume phase transition characteristics with tunable swelling kinetics, i.e. the particle swelling was induced by an increase rather than a decrease in temperature. The monodisperse poly(AAM-co-St) seeds were prepared by emulsifier-free emulsion polymerization, the PAAM or poly(acrylamide-co-butyl methacrylate) (poly(AAM-co-BMA)) shells were fabricated on the seeds by free radical polymerization, and the core-shell microspheres with PAAM/PAAC based IPN shells were finished by a method of sequential IPN synthesis. The microsphere size increased with increasing both AAM and BMA dosages. The increase of hydrophilic monomer AAM dosage resulted in a better monodispersity, but the increase of hydrophobic monomer BMA dosage led to a worse monodispersity. With increasing the crosslinker methylenebisacrylamide (MBA) dosage, the mean diameter of the microspheres decreased and the monodispersity became better. An equimolar composition of AAC and AAM in the IPN shells of the microspheres resulted in a more complete shrinkage for the microspheres at temperatures lower than the upper critical solution temperature. Both BMA and MBA additions depressed the swelling ratio of the hydrodynamic diameter of the microspheres.     

Amphiphilic ethyl cellulose brush polymers with mono and dual side chains: Facile synthesis,self-assembly,and tunable temperature-pH responsivities

Novel amphiphilic ethyl cellulose (EC) brush polymers with mono and dual side chains of poly(2-(2-methoxyethoxy)ethyl methacrylate)-co-oligo(ethylene glycol) methacrylate) (P(MEO₂MA-co-OEGMA)) and poly(2-(N,N-dimethylamino)ethyl methacrylate) (PDMAEMA) were synthesized by the combination of atom transfer radical polymerization (ATRP) and click chemistry. The molar ratio of P(MEO₂MA-co-OEGMA) and PDMAEMA was varied through changing the feed ratio of these polymers and the coupling efficiency of click chemistry is relatively high. The brush polymers can self-assemble into spherical micelles/aggregates. The micelles/aggregates show the tunable temperature-pH responsive properties. The cloud points and the pH-triggered phase transition were influenced by EC chains and the ratio of P(MEO₂MA-co-OEGMA) and PDMAEMA side chains. The brush polymers have the great potential applications as biomedical or intelligent materials.     

Composite latex production with high solid content

Poly(methyl methacrylate-co-butyl acrylate) (PMMA-co-PBA) and poly(sytrene-co-butyl acrylate) (PSt-co-PBA) latexes in which solid content (SC) varied from 20% up to 40 wt % armored with laponite clay have been successfully synthesized using a simple method, which does not require modification of the clay particles prior to polymerization. Incorporation of quite high amounts of laponite nanoparticles into PMMA-co-PBA and PSt-co-PBA latexes with a certain amount of solids content was achieved. The nanocomposite latexes and polymer samples were characterized using Fourier transform infrared (FTIR) spectroscopy in attenuated total reflectance (ATR) mode, dynamic light scattering (DLS), X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), contact angle, zeta potential, viscosimetry and analytical ultracentrifuge (AUC). Zeta potential values showed that stable latex was obtained and precipitation problem of the nanoparticles in the latex was not seen during the storage. Obtained nanocomposite latex showed fine particle size between 88 and 160 nm. TEM images and XRD results pointed out that the exfoliated nanocomposite structure for latexes was obtained. DSC analyzes showed that the glass-transition temperature (T _g) values of nanocomposite films decreased slightly compared with those of pure (PMMA-co-PBA) films. Mechanical properties of laponite clay armored PMMA-co-PBA were tested and compared with those of pure PMMA-co-PBA, indicating that incorporated the Young's modulus and tensile strength are also improved to a noticeable extent after the incorporation of laponite. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47423.     

乙烯基单体改性水性聚氨酯的研究

采用种子聚合的方法，用甲基丙烯酸甲酯和苯乙烯对水性聚氨酯进行共混接枝改性．研究了改性后的水性聚氨酯的力学性能、吸水率、红外光谱特征、结果表明：乙烯基单体改性水性聚氨酯能提高力学性能、降低吸水率．其中甲基丙烯酸甲酯的氢键作用强，有较好的相容性．苯乙烯的氢键作用小．相分离程度最大。     

Miscible chitosan/tertiary amide polymer blends

The miscibility of five chitosan/tertiary amide polymer blend systems was studied. Based on the optical transparency of the blend and the existence of a single glass transition temperature, chitosan was found to be miscible with poly(N‐vinyl‐2‐pyrrolidone), poly(N‐methyl‐N‐vinylacetamide), poly(N,N‐dimethylacrylamide), poly(2‐methyl‐2‐oxazoline), and poly(2‐ethyl‐2‐oxazoline). Fourier transform infrared spectroscopy showed the existence of hydrogen‐bonding interactions between chitosan and the tertiary amide polymers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1785–1790, 2000     

Surface hardness and transparency of poly(methyl methacrylate)‐silica coat film derived from perhydropolysilazane

To prepare hard and transparent poly (methyl methacrylate)‐silica coat film on glass or polycarbonate substrates, poly(methyl methacrylate‐co‐2‐hydroxyethyl methacrylate) random copolymers and perhydropolysilazane (PHPS) were blended in solution. Then the solution was cast on the substrates. The grafting of PHPS onto 2‐hydroxyethyl methacrylate unit was analyzed by ¹H NMR spectroscopy. Surface hardness and transparency of the coat film were measured by nano‐indentation method and UV‐Vis spectroscopy, respectively. Surface hardness of coat film depended on the volume fraction of silica in the coat film, and reached 2.7 GPa when the volume fraction of silica was 76.4%. Transparency of the coat films prepared with PHPS was almost 100%, indicating that the coat film prepared with PHPS was highly transparent not only on glass substrate but also on the polycarbonate substrate. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Studies on inherently radiopaque acrylate copolymers for biomedical applications

Poly(glycidyl methacrylate-co-ethyl methacrylate) and poly(glycidyl methacrylate-co-butyl methacrylate) random copolymers (with 50–50 mol % of monomers) were made radiopaque by grafting iodine moieties through the ring opening reaction of the epoxy groups. The percentage weight of grafted iodine in the copolymers was found to be as high as 19%. The iodinated copolymers showed higher glass transition temperature and thermal stability in comparison with the parent copolymers. Iodinated copolymer of poly(glycidyl methacrylate-co-ethyl methacrylate) has improved glass transistion temperature than iodinated poly(glycidyl methacrylate-co-butyl methacrylate). Radiographic analysis of these iodinated copolymers showed excellent radiopacity. The in vitro cytotoxicity tests revealed cytocompatibility with cells. These radiopaque copolymers are expected to find application as dental and orthopedic cements. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012