Effect of sequence structure on wetting behaviors of fluorinated methacrylate polymers based on perfluorohexylethyl methacrylate and stearyl acrylate

Due to the non-crystalline properties of short chain perfluoroalkyl groups,using short chain perfluoroalkyl to stabilize low surface free energy polymers has been a challenging task.In this study,we prepare a series of random copolymers poly(perfluorohexylethyl methacrylate)-co-poly(stearyl acrylate) (P13FMA-co-PSA) and block copolymers poly(perfluorohexylethyl methacrylate)-b-poly(stearyl acrylate) (P13FMA-b-PSA),and systematically investigate the effects of the sequence structure and the content of 13FMA of the fluorinated copolymers on surface free energy and surface reorganization.Static/dynamic contact angle goniometry and water/oil repellency analyses demonstrate that the random polymer P13FMA-co-PSA could not achieve low surface free energy and low surface reorganization at the same time.In contrast,for the block copolymer P13FMA-b-PSA,both low surface free energy and low surface reorganization are acquired simultaneously.The results of X-ray photoelectron spectroscopy (XPS),dynamic contact angle goniometry and differential scanning calorimetry (DSC) reveal the above-mentioned properties.The consecutive 13FMA segments improve the surface fluorine density,while the consecutive SA chains enhance the crystallinity of the SA segments,and further hinder the surface reorganization of the perfluoroalkyl groups.Therefore,P13FMA-b-PSA exhibits a higher utilization efficiency of fluorine atoms and a better structural stability than P13FMA-co-PSA.     

Characterization of the interaction energies for polystyrene blends with various methacrylate polymers

The binary interaction energies between styrene and various methacrylates were determined from newly examined phase boundaries with lattice–fluid theory. Because the blends of polystyrene (PS) and poly(cyclohexylmethacrylate) (PCHMA) were only miscible at high molecular weights when the blends were prepared by solution casting from tetrahydrofuran, we examined the miscibility of other blends by changing the molecular weights of PS or methacrylate polymers. On the basis of the phase‐separation temperature caused by the lower critical solution temperature, the miscibility of PS with the various methacrylates appeared to be in the order PCHMA > poly(n‐propyl‐methacrylate) (PnPMA) > poly(ethyl methacrylate) (PEMA) > poly(n‐butyl‐methacrylate) (PnBMA) > poly(iso‐butyl‐methacrylate) > poly(methyl methacrylate) (PMMA) > poly(tert‐butyl methacrylate), and the branching of butylmethacrylate appeared to decrease the miscibility with PS. The interaction energies between PS with various methacrylates obtained from phase boundaries with lattice–fluid theory reached minimum value corresponding to the styrene/n‐propylmethacrylate interaction. They were in the order PnPMA < PEMA < PCHMA < PnBMA < PMMA. The difference in the order of miscibility and interaction energies might be attributed to the terms related to the compressibility. The phase‐separation temperatures calculated with the interaction energies obtained here indicated that the PS/PEMA and PS/PnPMA blends at high molecular weights were miscible, whereas the PS/PnBMA blends were immiscible at high molecular weights. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2666–2677, 2000     

Pervaporation performance of novel chitosan‐POSS hybrid membranes: Effects of POSS and operating conditions

Four types of polyhedral oligosilsesquioxane (POSS)–octaanion, octaammonium, octanitrophenyl, and octaaminophenyl–were incorporated into chitosan (CS) to fabricate inorganic–organic hybrid membranes. The hybrid membranes were employed for the pervaporation dehydration of ethanol aqueous solutions. The performance of the hybrid membranes was found to be influenced by the type and loading amount of POSS. In comparison with the neat CS membranes which showed a separation factor of 65.2 for 10 wt % water in the feed at 303 K, the hybrid membranes containing 5 wt % of octaanion and octaaminophenyl POSS showed high separation factors of 305.6 and 373.3, respectively. The effects of the operating conditions such as the feed composition and temperature on the pervaporation performance of the membranes were investigated. Activation energies for permeation in the membranes were estimated from Arrhenius relationship. The activation energies for ethanol permeation in the hybrid membranes were much higher than that in the CS membrane, which may account for the large enhancements in the selectivity of the hybrid membranes. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010     

Group transfer polymerization in the bulk: linear polymers and randomly cross-linked networks

Linear homopolymers and randomly cross-linked homopolymer networks of 2-(dimethylamino)ethyl methacrylate of various molecular weights (MWs) were synthesized by group transfer polymerization in the bulk. 1-methoxy-1-(trimethylsiloxy)-2-methyl propene was used as the initiator, while tetrabutylammonium bibenzoate served as the catalyst. Ethylene glycol dimethacrylate was the cross-linker used for the network synthesis at an 8-fold molar excess with respect to the initiator. Gel permeation chromatography in tetrahydrofuran was used to characterize the linear homopolymers in terms of their MW and molecular weight distribution (MWD). Although the experimental MWs did not match the theoretical MWs, they were reasonably close to them. The MWDs were rather broad with polydispersity indices ranging between 1.5 and 1.9. The monomer conversion was relatively high, ranging from 97% to 74% for theoretical degrees of polymerization (DPs) from 5 to 500. No polymerization was observed for an attempted DP of 1000. Networks with molar ratios of monomer to initiator (nominal DPs) from 5 to 200 were prepared, while an attempted synthesis with a nominal DP of 500 did not yield a network. The networks were characterized in terms of their degree of swelling in water and the effects of DP, pH, salt concentration and temperature were investigated.     

Surface modification of natural rubber film by polymerisation of methyl methacrylate in water-based system

Polymerisation of methyl methacrylate (MMA) on the surface of natural rubber (NR) film was studied in order to increase the surface hardness, roughness and, hence, to decrease the friction coefficient of rubber. We used the two-step process: (i) swelling of MMA and tert-butyl hydroperoxide, emulsified in an aqueous solution of sodium dodecyl sulphate, onto the NR film surface, and (ii) subsequently immersing the swollen rubber strip into an alkaline aqueous solution of ferrous ion/fructose for redox initiation. The presence of PMMA on the NR surface was examined by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). Increasing the concentration of ferrous ion caused an increase in MMA conversion. The surface morphology observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) in tapping mode revealed the aggregation of micronmetre-scale nodules on the modified surface. The surface hardness and roughness increased with increasing PMMA content.     

Phase behavior of tetramethylpolycarbonate blends with styrene‐based methacrylate copolymers and their interaction energies

The miscibility of tetramethylpolycarbonate (TMPC) blends with styrenic copolymers containing various methacrylates was examined, and the interaction energies between TMPC and methacrylate were evaluated from the phase‐separation temperatures of TMPC/copolymer blends with lattice‐fluid theory combined with a binary interaction model. TMPC formed miscible blends with styrenic copolymers containing less than a certain amount of methacrylate, and these miscible blends always exhibited lower critical solution temperature (LCST)‐type phase behavior. The phase‐separation temperatures of TMPC blends with copolymers such as poly(styrene‐co‐methyl methacrylate), poly(styrene‐co‐ethyl methacrylate), poly(styrene‐co‐n‐propyl methacrylate), and poly(styrene‐co‐phenyl methacrylate) increase with methacrylate content, go through a maximum, and decrease, whereas those of TMPC blends with poly(styrene‐co‐n‐butyl methacrylate) and poly(styrene‐co‐cyclohexyl methacrylate) always decrease. The calculated interaction energy for a copolymer–TMPC pair is negative and increases with the methacrylate content in the copolymer. This would seem to contradict the prediction of the binary interaction model, that systems with more favorable energetic interactions have higher LCSTs. A detailed inspection of lattice‐fluid theory was performed to explain such phase behavior. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1288–1297, 2002     

Preparation of composite materials containing iron in a cross-linked resin host based on styrene and divinylbenzene

Iron composite materials based on styrene/divinylbenzene network hosts were produced using aqueous suspension polymerization. The effects of different kinds of porogen agent, toluene, toluene/n-heptane mixture or a toluene solution of polyphenyleneoxide on the bulk density, swelling in toluene and ferromagnetic properties of these materials were evaluated. The specific area and average porous diameter of network resins were characterized by BET and BJH methods, while the iron content was determined by atomic absorption spectrometry. The morphology of the composites was studied by both optical microscopy and scanning electron microscopy with energy dispersive X-ray analysis. All the spherical beads, irrespective of their sizes, have agglomerated iron particles located only on their surface. The particles have exhibited ferromagnetic behavior, with a coercivity of 328.69 Oe. The porogen agents used affect the iron particle distribution on the bead surfaces.     

Surface characterization of macroporous glycidyl methacrylate based copolymers by inverse gas chromatography

Two samples of macroporous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate), PGME, with different porosity parameters were synthesized by suspension copolymerization and modified by ring-opening reaction of the pendant epoxy groups with ethylene diamine, EDA. Inverse gas chromatography at infinite dilution was used for the determination of adsorption properties of PGME, and copolymer modified with ethylene diamine, PGME-en. Thermodynamic parameters of adsorption, dispersive components of the surface free energies, and the acid/base constants for the copolymer samples were calculated. The calculated dispersive surface energy values, , for PGME and PGME-en are comparable with the literature data for nonconductive polymers.     

关于表面张力和表面自由能的讨论

简要地回顾了表面物理化学中表面张力和表面吉布斯自由能(以下简称为表面自由能)两个基本概念的发展历史,讨论了表面张力和表面自由能形成的机制,以及键能与表面张力的关系,最后指出了尽管表面相可以在理论上抽象为几何面,但它是真实存在的独立相,而且由于表面自由能的原因它始终处于亚稳定状态.     

Incorporation of POSS to improve thermal stability of bio-based polymethacrylates by nitroxide-mediated polymerization: Polymerization kinetics and characterization

Nitroxide-mediated polymerization (NMP) was used to polymerize methacrylate-functionalized polyhedral oligomeric silsesquioxane, POSSMA, in a controlled manner with bio-based C13 methacrylate (C13MA) to improve the thermal stability of the latter by copolymerization (using 10 mol% acrylonitrile controlling comonomer). Kinetic experiments (80–110 °C) revealed the relatively low ceiling temperature of POSSMA (135 °C). Synthesis of poly(POSSMA-co-AN) with f _AN,0 = 0.10 at 90 °C resulted in low dispersity (1.16) and relatively high conversion (~50%) after 3 hr in 50 wt% toluene. Assuming binary statistical copolymerizations, POSSMA was slightly less reactive than C13MA toward the propagating species (r _POSSMA = 0.91 ± 0.07 and r _C13MA = 1.94 ± 0.13). Incorporating POSSMA up to 68 mol% improved decomposition temperature of C13MA-based copolymers from 190 to 262 °C. Chain end fidelity of POSSMA-rich compositions was confirmed by subsequent chain extensions to make block and gradient copolymers. Differential scanning calorimetry revealed multiple transition temperatures in block copolymers, suggesting microphase separation. Powder X-ray diffraction confirmed crystalline domains ~30 nm in POSSMA-rich statistical copolymers while transmission electron microscopy revealed weakly ordered lamellar morphology for poly(C13MA-co-AN)-b-(POSSMA-co-AN) block copolymer at a smaller length scale. Oscillatory shear measurements of block copolymers indicated primarily viscous character below 200 s⁻¹ but crossover above this frequency, indicating POSS–POSS interactions were increasing the elasticity of the block copolymers.     

具有低表面自由能有机介电薄膜的制备及表征

通过自主开发的有机镀膜技术在Mg-Mn-Ce镁合金表面制备了具有低表面自由能和较高介电常数的有机纳米薄膜. 利用X射线光电子能谱(XPS)分析了表面有机镀膜过程的反应机理, 借助傅里叶变换红外(FT-IR)光谱进一步确认表面有机膜层的存在, 采用接触角测量仪测定了有机薄膜的蒸馏水接触角和表面自由能变化, 使用椭圆偏振光谱仪研究了薄膜的厚度, 并借助精密阻抗分析仪评价了薄膜的介电性能. 有机镀膜后镁合金表面形成了一层纳米级厚度的有机薄膜, 接触角从基体的70.8°上升至150.5°, 表面自由能从基体的37.96 mJ·m^-2降低到1.57 mJ·m^-2, 镁合金表面从亲水性转变为疏水性; 薄膜的厚度和质量随有机镀膜时间延长先增加后有所减小, 在镀膜20 min时薄膜性能最佳, 此时膜重达到23.5 μg·cm^-2, 膜厚最大为147.48 nm, 其相对介电常数也达到最大, 在1 kHz下可达24.922.     

Synthesis of linear and starlike polymers from poly(propylene glycol) methacrylate using controlled radical polymerization

The copper‐catalyzed atom transfer radical polymerization (ATRP) of poly(propylene glycol) methacrylate (PPGM) in solution to produce linear and starlike polymers is reported, using methylethyl ketone as the solvent and a temperature of 80 °C. The ATRP system used was efficient for polymerization of the functionalized monomer without protecting hydroxyl end groups of monomer. The polymerizations were consistent with “living” or controlled processes, as revealed by the linear evolution of molecular weight with conversion. Increasing the [M]₀:[I]₀ ratio resulted in increasing molecular weights, whereas the polydispersity indices remained low (M_w/M_n < 1.4) even at high conversion. Decreasing the [CuBr]₀:[I]₀ ratio resulted in lower conversions, slightly larger polydispersities, and decreased molecular weights, likely resulting from a lower initiation efficiency. Polymers were characterized by ¹H and ¹³C NMR; molecular weights of polymers with low degrees of polymerization were estimated by end‐group analysis from ¹³C NMR spectra obtained using distortionless enhancement by polarization transfer and the gated decoupling techniques. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 334–343, 2002     

Bound fractions of methacrylate polymers adsorbed on silica using FTIR

The H‐bonding of carbonyl groups on a series of methacrylate polymers with silanols on fumed silica was studied with transmission FTIR. The set included poly(alkyl methacrylates) with alkyl groups, (n‐C_nH_2n+1) of n = 1, 2, 4, and 12 and poly(benzyl methacrylate). Shifts in the vibrational frequencies for bound carbonyl groups (of ～20 cm^?1 lower than those found in the bulk) were observed in the adsorbed polymer samples. A series of samples with different adsorbed amounts (varying from 0.5 to 2.0 mg m^?2) of each polymer was prepared to determine the effect of the side chain on the H‐bonding. The fractions of bound carbonyls, p, for each of the methacrylate polymers studied, were calculated from a model based on the ratios of the absorption coefficients of the bound to free carbonyl resonances, X (= α_b/α_f). The X values were determined from linear regressions of the ratios of the free to bound carbonyl intensities as a function of the amounts of adsorbed polymer, M_t. The bound fractions, p, were observed to decrease with increase in adsorbed amounts and with increase in the lengths of the side chains of the methacrylate polymers, except for poly(lauryl methacrylate) (PLMA). PLMA has a very low glass transition temperature (T_g) and is likely rubbery on the surface, whereas the other polymers are likely glassy at ambient temperature. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1911–1918, 2010     

Development of reactive methacrylates based on glycidyl methacrylate

Six methacrylate monomers have been synthesized for use as reactive diluents in dental composites and evaluated to investigate the relationship between molecular structure and monomer reactivity. Four were synthesized by reactions of glycidyl methacrylate (GMA) with various acids, 2‐(2‐methoxyethoxy)acetic acid ( 1 ), 2‐(2‐(2‐methoxyethoxy)ethoxy)acetic acid ( 2 ), cyanoacetic acid ( 3 ), and benzoic acid ( 4 ); others were synthesized by reactions of GMA with diethyl hydrogen phosphate ( 5 ) or methanol ( 6 ). Monomers 1 and 2 are novel, 3 seems to be novel, 4 and 6 were synthesized via a novel method, and the synthesis of 5 was described in the literature. The monomers showed high crosslinking tendencies during thermal bulk polymerizations. The photo‐, homo‐, and copolymerization behavior of the monomers with 2,2‐bis[4‐(2‐hydroxy‐3‐methacryloyloxy)phenyl]propane (Bis‐GMA) were investigated. The maximum rate of polymerizations of monomers 2 – 6 was found to be greater than triethyleneglycol dimethacrylate, Bis‐GMA, 2‐hydroxyethyl methacrylate, and glycerol dimethacrylate. For the more reactive monomers ( 2 , 3 , and 4 ), the oxygen sensitivity of polymerization was found to be low due to a hydrogen abstraction/chain transfer reaction. The computationally calculated dipole moment and lowest unoccupied molecular orbital energies indicated that there seems to be a correlation between these quantities and reactivity for ester linked monomers ( 1 – 5 ), which was also supported by ¹³C NMR data. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3787–3796, 2010     

Construction of new cross-linked supramolecular polymer with FRET phenomenon based on oligo(p-phenylenevinylene)-linked pillar[5]arene dimer

Cross-linked supramolecular polymers generally show distinct mechanical properties with intriguing functions, which have become one of the hot research topics in recent years. However, the cross-linked supramolecular polymers functionalised with fluorescence resonance energy transfer (FRET) properties have been rarely reported yet. Herein, a new cross-linked supramolecular polymer equipped with efficient FRET property was constructed successfully. The oligo(p-phenylenevinylene)-linked pillar[5]arene dimer (PA-OPV) functioned as a host and energy donor, while four pentanenitrile groups coupled porphyrin (CN-Por) acted as guest with energy acceptor. The supramolecular polymerisation and FRET properties were investigated by using NMR, viscosity, Fluorescence, UV–vis and SEM.     

Structure–property relationship of octa‐substituted POSS in thermal and mechanical reinforcements of conventional polymers

In this article, we describe the structure–property relationships between the polyoctahedral oligomeric silsesquioxane (POSS) fillers and the thermomechanical properties of the polymer composites using polystyrene, poly(methyl methacrylate), and ethylene‐(vinyl acetate) copolymer. We used eight kinds of octa‐substituted aliphatic and aromatic POSS as a filler, and homogeneous polymer composites were prepared with various concentrations of these POSS fillers. From a series of measurements of thermal and mechanical properties of the polymer composites, it was summarized that the longer alkyl chains and unsaturated bonds at the side chains in POSS are favorable to improve the thermal stability and the elasticity of polymer matrices. It was found that phenyl‐POSS can show superior ability to improve the thermomechanical properties of conventional polymers used in this study. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5690–5697, 2009     

Synthesis of triblock and multiblock methacrylate polymers and self‐assembly of stimuli responsive triblock polymers

Multisegmented poly(methacrylate)s were synthesized using one pot reversible addition fragmentation chain transfer polymerization. Initially, a series of triblock copolymers were synthesized with different ratios of trimethylsilyl methacrylate, di(ethylene oxide) methacrylate, and oligo(ethylene oxide) methacrylate, and different total polymer molecular weights. Additionally, a polymer containing seven distinct blocks of methacrylic monomers was synthesized in one pot. For the triblock copolymers, the trimethylsilyl group was subsequently hydrolyzed, and the self‐assembly of the triblock copolymer was studied in water, under different pH and thermal conditions. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2548–2555     

Synthesis and self‐catalyzed phase transfer reaction of novel methacrylate polymers

Ethyl α‐chloromethylacrylate was converted to an ester derivative using 5‐chlorovaleric acid in a single step. The homopolymerization of the new monomer (CEMA) and its copolymerization with methyl methacrylate were performed using photoinitiator Irgacure 651. The polymers were reacted with N,N‐dimethyldodecylamine to obtain polymers with pendant quaternary ammonium (QA) moieties. The polymers with pendant QA groups were used in self‐catalyzed phase transfer reactions with sodium phenoxide and 1‐dodecanethiol. The syntheses of the monomer and polymers were followed by FTIR, ¹H NMR, and ¹³C NMR. The average polymer molecular weights and polydispersities were determined by size exclusion chromatography. Thermal analysis was carried out using thermogravimetric analysis and differential scanning calorimetry. The copolymer composition, degree of quaternization, and degree of conversion in phase transfer reaction were determined by ¹H NMR. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5844–5854, 2005     

Surface characterization of poly(2,2,3,3,3-pentafluoropropyl methacrylate) by inverse gas chromatography and contact angle measurements

A fluorinated methacrylic homopolymer, poly(2,2,3,3,3-pentafluoropropyl methacrylate) (PPFPMA) was synthesized by a free radical polymerization reaction. The dispersive component of the surface energy () of PPFPMA was determined by contact angle measurements and inverse gas chromatography (IGC). An extensive surface characterization was conducted by means of IGC. Surface characterization demonstrated that PPFPMA has low value, even at 35 °C and is a Lewis amphoteric polymer with predominantly basic character, as confirmed by the Lewis acidity and basicity constants K_A and K_B, respectively. The values of obtained by IGC are slightly higher than those obtained by the contact angle method. This trend can be attributed to the fact that IGC evaluates, primarily, high energy sites of a surface.     

Effect of POSS on crystalline transitions and physical properties of polyamide 12

Polyamide 12/Trisilanolphenyl‐POSS (PA 12/POSS) composites were prepared via melt‐compounding. The effect of polyhedral oligomeric silsesquioxane (POSS) on crystalline structure and crystalline transition of PA 12 was investigated by wide‐angle X‐ray diffraction (WAXD) and real time fourier transform infrared spectroscopy (FTIR). WAXD results indicated that PA 12 crystallized into γ‐form as slowly cooling from melt and the presence of POSS did not influence the crystalline structure of PA 12. Both PA 12 and PA 12/POSS composites underwent Brill transitions when they were heated from room temperature to melt point. Real time FTIR patterns showed that an absorption band at 697 cm^?1 ascribed to Amide V (α) mode was emerged along with the disappearance of Amide VI (γ) band at 628 cm^?1 with the increase of the temperature for PA 12 and PA 12/POSS composites, which suggested that the γ‐form crystalline has transformed into α form. The Brill bands were identified and the transformed mechanism was discussed based on the real FTIR results. The addition of POSS enhanced the tensile strength and thermal stability of PA 12. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 121–129, 2009