聚甲基丙烯酸甲酯/聚甲基丙烯酸-2-羟乙酯复合微球的合成及药物吸放性能

采用在甲基丙烯酸甲酯（MMA）悬浮聚合过程中滴加甲基丙烯酸-2-羟乙酯（HEMA）乳液聚合组分的悬浮-乳液耦合聚合方法,制备了大粒径聚甲基丙烯酸甲酯／聚甲基丙烯酸-2-羟乙酯（PMMA／PHEMA）复合微球。PMMA／PHEMA复合微球表面以HEMA乳液聚合物为主,且具有微孔结构。PMMA／PHEMA复合微球在水和苄醇中的平衡溶胀率大于PMMA微球。PMMA／PHEMA复合微球48h异丁苯丙酸负载百分比为35．6％,PMMA为27．6％。在磷酸盐缓冲液中释放时间达到360h,释放量占负载总量的82％;而PMMA微球的释放时间为216h,释放量仅占负载总量的60％。     

Evaluation of a polymer-steel laminated sheet composite structure produced by friction stir additive manufacturing (FSAM) technology

Laminated polymer-steel composites are promising layered materials for practical applications in the automotive industry considering their superior crush resistance capacity in terms of enhanced damping potential. In this research, the sheet lamination (SL) route of friction stir additive manufacturing (FTAM) technology was implemented for the production of a poly-methyl-methacrylate (PMMA) polymer matrix composite structure as reinforced by textile stainless steel layers, and feeding of PMMA granulates inside the stirred region. Layers bonding and the soundness of composite formation during fabrication of the laminated structure were studied. Possible chemical interactions between the steel and PMMA during friction stir mixing followed by solid-state consolidation of composite layers were characterized by X-ray photoelectron spectroscopy (XPS) analysis. The results revealed some evidence for dipole bonding between iron with oxygen and carbon elements. Orientation dependency of polymer-steel sheet laminated composite structures was demonstrated by universal tensile testing and flexural bending from different sections and fractographic analyses. Superior flexural bending (around 90% of PMMA) was shown for the produced layered structure.     

Synthesis of nano-ZnO/poly(methyl methacrylate) composite microsphere through emulsion polymerization and its UV-shielding property

Nano-ZnO/poly(methyl methacrylate)(PMMA) composite latex microspheres were synthesized by in-site emulsion polymerization. The interfacial compatibility between nano-ZnO particles and PMMA were improved by treating the surface of nano-ZnO particles hydrophobically using methacryloxypropyltrimethoxysilane (MPTMS). TEM indicated that nano-ZnO particles present in nanosphere and have been encapsulated in the PMMA phase. FT-IR confirmed that MPTMS reacted with the nano-ZnO particle and copolymerized with MMA. It was clearly found from SEM that ZnO nanoparticles can be homogeneously dispersed in the PVC matrix. The absorbance spectrum of the nanocomposite polymer suggested that increasing the amount of nano-ZnO in composite particles could enhance the UV-shielding properties of the polymers. The nano-ZnO/PMMA composite particle could eliminate aggregation of ZnO nanoparticle and improve its compatibility with organic polymer. This means that the composite particles can be widely applied in lots of fields.     

P(VDF-HFP)-PMMA/CaCO3(SiO2)复合聚合物电解质的电化学性质

采用激光扫描共焦显微镜、X射线衍射、循环伏安和交流阻抗等方法对由聚(偏二氟乙烯-六氟丙烯)(P(VDF-HFP))、聚甲基丙烯酸甲酯(PMMA)以及纳米碳酸钙(二氧化硅)制备的几种复合聚合物电解质(CPE)膜P(VDF-HFP)-PMMA/CaCO3(SiO2)的性能进行了研究. 结果表明, PMMA的加入能提高CPE的吸液率, 从而增大其离子导电率. 在P(VDF-HFP)与PMMA质量比为1:1条件下制得的CPE性能最佳. 用P(VDF-HFP)-PMMA为聚合物基体与纳米级SiO2、CaCO3进行复合制成的聚合物膜, 无机粒子的加入没有破坏原来聚合物非晶结构; 室温下CPE的电导率达到3.42 mS·cm-1; 电化学稳定窗口为4.8 V. 电池Li/CPE/GMS(石墨基材料)的测试证明, CPE与石墨负极有很好的相容性. 聚合物电池Li/CPE(CaCO3)/LiCoO2比Li/CPE)(SiO2)/LiCoO2具有更优越的倍率放电性能.     

Electrical and Structural Properties of Poly (Methyl Methacrylate) Doped Potassium Iodide (KI) Solid Polymer Electrolyte

A high-conducting salt-doped polymer electrolyte layer has been created here for use in photocell technologies. The solution casting method is used to produce ion conducting film where poly (methyl methacrylate) (PMMA) is used as the host polymer and potassium iodide (KI) as the dopant. The conductivity and amorphic increases of the polymer electrolytes with the addition of salt concentrations helps in the enhancement of the charge transfer properties. Using electrochemical impedance spectroscopy (EIS), ionic conductivity is evaluated where maximum conductivity is 3.99 × 10⁻⁶ S cm^-1 at 20 wt% KI concentration. Polarized optical microscopy (POM) shows the reduction in crystallinity by salt doping, while Fourier transforms infrared spectroscopy (FTIR) shows the complexation as well as composite nature of the film. Ionic transference number (t_ion) measurement shows the predominantly ionic nature of this polymer electrolyte.     

Thermogravimetric characterisation of poly(methyl methacrylate) photopolymerised by colloidal cadmium sulphide

The thermal stability of poly(methyl methacrylate) (PMMA) photopolymerised using colloidal cadmium sulphide as the photoinitiator was studied by thermogravimetry (TG) and differential TG (DTG).The thermal stability of the CdS initiated PMMA was greater than that of conventional radically polymerised PMMA and approached that of anionically prepared PMMA. The DTG curve of the CdS initiated PMMA was a composite of four peaks, three of which correspond to the three peaks observed in the DTG curve of standard radically prepared PMMA. It is suggested that the additional peak arises from a new mode of depolymerisation initiation, that is, from chain end unsaturation introduced into the polymer chain during polymerisation initiation with the colloidal CdS.     

Preparation of hemispherical particles by cleavage of micrometer-sized,spherical poly(methyl methacrylate)/polystyrene composite particle with Janus structure: effect of molecular weight

Micrometer-sized, hemispherical polymer particles were prepared as a result of cleavage of spherical Janus poly(methyl methacrylate) (PMMA)/polystyrene (PS) composite particle by treating particles with acetone/water solutions. The original PMMA/PS composite particles were prepared by the slow evaporation of toluene from homogeneous PMMA/PS/toluene droplets dispersed in aqueous solution of sodium dodecyl sulfate in advance. Appropriate molecular weights of PMMA and PS were necessary for occurrence of the cleavage of the Janus composite particle, resulting in PMMA and PS hemispherical particles. The cleavage depended on the composition of the acetone/water solution, which was explained by selective solvent absorption into the polymer phases. The results strongly support the cleavage mechanism of Janus composite polymer particles that had been proposed earlier.     

The effect of boron-containing layered hydroxy salt (LHS) on the thermal stability and degradation kinetics of poly (methyl methacrylate)

A boron-containing layered hydroxy salt (LHS), ZHTMDBB, was prepared and compounded with a highly flammable synthetic polymer, poly (methyl methacrylate) {PMMA}, via melt blending: the composite structure was intercalated with poor dispersion. The effect of this LHS on the flammability, thermal stability and degradation kinetics of PMMA was investigated via cone calorimetry and thermogravimetric analysis. The addition of 3-10% by mass of ZHTMDBB to PMMA resulted in significant reduction of peak heat release rate (22-48%) of the polymer and improvements in thermal stability were observed in both air and nitrogen. Effective activation energies for the degradation process were evaluated using Flynn-Wall-Ozawa, Friedman, and Kissinger methods. All three methods indicated that the additive increased the activation energies of the first step of the degradation process in both air and nitrogen. Activation energies of the second step were lowered in nitrogen but were not significantly affected in air.     

Conductivity of Poly(methyl methacrylate)/Polystyrene/Carbon Black and Poly(ethyl methacrylate)/Polystyrene/Carbon Black Ternary Composite Films

Poly(methyl methacrylate)(PMMA)/polystyrene(PS)/carbon black(CB)and poly(ethyl methacrylate)(PEMA)/PS/CB ternary composite films were obtained using solution casting technique to investigate double percolation effect.In both PMMA/PS/CB and PEMA/PS/CB ternary composite films,the CB particles prefer to locate into PS phase based on the results of calculating wetting coefficient,which is also confirmed by SEM images.The conductivity of the films was investigated,and the percolation threshold(￠c)of both ternary composite films with different polymer blend ratios was determined by fitting the McLachlan GEM equation.Conductivity of PMMA/PS/CB ternary composite films showed a typical double percolation effect.However,due to the double emulsion structure of PEMA/PS polymer blends,the PEMA/PS/CB ternary composite films(PEMA/PS=50/50)showed a higher￠c,even CB only located in PS phase,which conflicts with the double percolation effect.A schematic diagram combined with SEM images was proposed to explain this phenomenon.     

悬浮-乳液复合聚合聚苯乙烯-聚甲基丙烯酸甲酯复合粒子的颗粒特性和成粒机理

采用在苯乙烯 (St)悬浮聚合过程中滴加甲基丙烯酸甲酯 (MMA)乳液聚合组分的悬浮 乳液复合聚合方法 ,制备大粒径聚苯乙烯 聚甲基丙烯酸甲酯 (PS PMMA)复合粒子 .研究聚合物粒径分布和颗粒形态的变化发现 ,在St悬浮反应中期滴加MMA乳液聚合组分后 ,聚合体系逐渐由悬浮粒子与乳胶粒子并存向形成单峰分布复合粒子转变 ,最终形成核 壳结构完整的大粒径PS PMMA复合粒子 ;在St悬浮反应初期滴加MMA乳液聚合组分 ,St与MMA一起分散成更小液滴 ,反应后期凝并成非核 壳结构复合粒子 ;在St悬浮反应后期滴加MMA乳液聚合组分 ,PMMA乳胶粒子与PS悬浮粒子基本独立存在 .根据以上结果 ,提出了St MMA悬浮 乳液复合聚合的成粒机理 .     

Preparation of Hemispherical Polymer Particles by Cleavage of a Janus Poly(methyl Methacrylate) /Polystyrene Composite Particle

Micrometer-sized, hemispherical particles were successfully prepared as a result of the cleavage of Janus PMMA/PS composite particles by dispersion into acetone/water (9/1-10/0 v/v) media or a THF/water (8/2 v/v) medium. The spherical composite particles having a Janus structure were prepared by the slow evaporation of toluene from homogeneous PMMA/PS/toluene droplets dispersed in an aqueous medium in advance. It was clarified that the difference in affinity between PMMA and PS phases with respect to the media caused the cleavage of the composite particles. This method is expected to be a novel approach to the preparation of nonspherical polymer particles.     

Differential thermal studies of polymethyl methacrylate-impregnated cement pastes

Differential thermal curves have been obtained for two polymethyl methacrylate-impregnated cement pastes prepared at a water/cement ratio of 0.37 and 0.70. Complex thermal effects, including a substantial decrease in the endothermal peak for Ca(OH)₂ decomposition, were observed in samples heated in air. These effects originate in the portland cement paste, in the polymer, and from interactions between the polymer and the hydrated cement during heating. Less complex effects resulted when DTA was carried out in N₂. There was no evidence of a reaction between the hydrated cement and PMMA during impregnation.     

Effects of organoclays on morphology and thermal and rheological properties of polystyrene and poly(methyl methacrylate) blends

Morphology, thermal and rheological properties of polymer‐organoclay composites prepared by melt‐blending of polystyrene (PS), poly(methyl methacrylate) (PMMA), and PS/PMMA blends with Cloisite® organoclays were examined by transmission electron microscopy, small‐angle X‐ray scattering, secondary ion mass spectroscopy, differential scanning calorimetry, and rheological techniques. Organoclay particles were finely dispersed and predominantly delaminated in PMMA‐clay composites, whereas organoclays formed micrometer‐sized aggregates in PS‐clay composites. In PS/PMMA blends, the majority of clay particles was concentrated in the PMMA phase and in the interfacial region between PS and PMMA. Although incompatible PS/PMMA blends remained phase‐separated after being melt‐blended with organoclays, the addition of organoclays resulted in a drastic reduction in the average microdomain sizes (from 1–1.5 μm to ca. 300–500 nm), indicating that organoclays partially compatibilized the immiscible PS/PMMA blends. The effect of surfactant (di‐methyl di‐octadecyl‐ammonia chloride), used in the preparation of organoclays, on the PS/PMMA miscibility was also investigated. The free surfactant was more compatible with PMMA than with PS; the surfactant was concentrated in PMMA and in the interfacial region of the blends. The microdomain size reduction resulting from the addition of organoclays was definitely more significant than that caused by adding the same amount of free surfactant without clay. The effect of organoclays on the rheological properties was insignificant in all tested systems, suggesting weak interactions between the clay particles and the polymer matrix. In the PS system, PMMA, and organoclay the extent of clay exfoliation and the resultant properties are controlled by the compatibility between the polymer matrix and the surfactant rather than by interactions between the polymer and the clay surface. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 44–54, 2003     

Ba0.6Sr0.4TiO3/聚偏氟乙烯-聚甲基丙烯酸甲酯复合材料的制备及其介电性能

采用流延热压工艺制备Ba_0.6Sr_0.4TiO₃(BST)/聚偏氟乙烯(PVDF)?聚甲基丙烯酸甲酯(PMMA)复合薄膜,研究了PMMA含量对复合材料微观组织结构和介电性能的影响规律。结果表明,BST相能够均匀分散在聚合物基体中,归因于PMMA与PVDF良好的相容性,2种聚合物之间的界面不分明;随着PMMA含量的增加,复合材料的介电常数先降低后升高,耐击穿强度和介电可调性先增加后减少。PMMA含量(体积分数)为15%的BST/PVDF?PMMA₁₅复合材料的综合性能最佳:介电常数为23.2,介电损耗为0.07,耐击穿强度为1412 kV·cm^-1,在550 kV·cm^-1偏压场下,介电可调性为26.2%。     

Surface modification of poly(methyl methacrylate) microfluidic devices for high-resolution separations of single-stranded DNA

While polymer-based microfluidic devices offer some unique opportunities in developing low-cost systems for a variety of application areas, the ability to sort electrophoretically with high efficiency a number of different targets has remained somewhat elusive with an example consisting of achieving single base resolution as required for DNA sequencing. While the reasons for this are many-fold, it is clear that some type of coating is required on the polymer substrate to suppress the EOF and/or minimize potential solute/wall interactions. To this end, we report on a simple grafting procedure to allow the formation of polymer coats, which in this example used linear polyarcylamides (LPAs), onto a poly(methyl methacrylate) (PMMA) microfluidic device. The procedure involved creating an amine-terminated PMMA surface by appropriately functionalizing the PMMA through either a chemical or photochemical process. The aminated surface could then be used to covalently anchor methacrylic acid, which was used as a scaffold to produce LPAs on the surface through radical polymerization of acrylamide. The resulting surfaces demonstrated EOFs that were nearly an order of magnitude smaller than native PMMA. In addition, these LPA-coated devices could produce highly reproducible migration times of over approximately 20 runs with plate numbers exceeding 10(5) m(-1). Using gel electrophoretic analysis of a single base track generated from an M13mp18 template using Sanger cycle sequencing and dye-primer chemistry, the resolution value obtained for bases 199 and 200 was 0.18 while for bases 208 and 209 it was 0.21. For the native PMMA, these bands were found to comigrate.     

Cellulose acetate/poly(methyl methacrylate) interpenetrating networks: synthesis and estimation of thermal and mechanical properties

IPN-type composites consisting of cellulose acetate (CA) and poly(methyl methacrylate; PMMA) were successfully synthesized in film form. In this synthesis, a mercapto group (SH)-containing CA, CA-MA, was prepared in advance by esterification of CA with mercaptoacetic acid, and then intercomponent cross-linking between CA-MA and PMMA was attained by thiol–ene polymerization of methyl methacrylate (MMA) onto the CA-MA substrate. For comparison, polymer synthesis was also attempted to produce a semi-IPN type of composites comprising CA and cross-linked PMMA, via copolymerization of MMA and ethylene glycol dimethacrylate as cross-linker in a homogeneous system containing CA solute. Thermal and mechanical properties of thus obtained polymer composites were investigated by differential scanning calorimetry, dynamic mechanical analysis, and a tensile test, in correlation with the mixing state of the essentially immiscible cellulosic and methacrylate polymer components. It was shown that the specific IPN technique using thiol–ene reactions usually resulted in a much better compatibility-enhanced polymer composite, which exhibited a higher tensile strength and even an outstanding ductility without parallel in any film sample of CA, PMMA, and their physical blends.     

Biological Activity of an Injectable Biphasic Calcium Phosphate/PMMA Bone Cement for Induced Osteogensis in Rabbit Model

Polymethylmethacrylate (PMMA) bone cement is widely used in repair of vertebral fracture because of its good biomechanical properties and fast curing. However, the bioinertness of PMMA cement may cause interfacial loosening, fatigue, fracture, and ultimate failure. In this study, biphasic calcium phosphate (BCP) is introduced into PMMA cement to prepare an injectable composite bone cement (BCP_x/PMMA) and the content of BCP is optimized to achieve appropriate rate of absorption that matches the bone regeneration. The compressive strength of BCP_x/PMMA bone cement is found to comply with the International Standardization Organization standard 5833, and can promote biomineralization as well as adhesion, proliferation, and osteogenic differentiation of Sprague‐Dawley rat bone marrow mesenchymal stem cells in vitro. Furthermore, in vivo test performed on a rabbit radius defect model demonstrates that the presence of BCP can significantly improve the osteogenic efficacy of PMMA cement. Therefore, it is anticipated that BCP_x/PMMA bone cement, as a promising injectable biomaterial, is of great potential in bone tissue regeneration.     

Depth-profiling of polymer laminates using fourier transform infrared (ATR) spectroscopy: The barrier film technique

We report FTIR-ATR spectra of a polymer laminate (PMMA/PVOH) at different base layer thicknesses and different angles of incidence on a ZnSe substrate. By varying this ‘barrier’ layer (of PMMA) we have demonstrated that different effective penetration depths into the PVOH are achieved, in very good agreement with the calculated electric fields as a function of distance away from the substrate surface. Such work forms the basis for depth profiling measurements in order to detect interfacial interactions between the polymer molecules. © 1994 John Wiley & Sons, Inc.     

Chemical force titrations of antigen- and antibody-modified poly(methylmethacrylate)

Poly(methylmethacrylate) (PMMA) is a versatile polymer that displays desirable properties for development of cheap and disposable microfluidic devices for sensing biomolecular interactions. Atomic force microscopy (AFM) and chemical force titrations were used to determine the efficacy of surface modifications made to accommodate protein-substrate linkage. AFM images show the effects on surface morphology of carboxylated-, amine-, hCG antigen- and anti-hCG antibody-modified PMMA substrates. Confocal microscopy was used to determine the fluorescent intensity of labeled antibody species on the PMMA substrate, confirming the success of surface antigen/antibody immobilization. Surface pK(1/2) value for carboxylic acid and amine species grafted on PMMA were determined. When carboxylic acid or amine-terminated tips were titrated against PMMA samples terminated with the hCG antigen and anti-hCG antibody, peaks appeared in the force titration curve consistent with the pI range of the antigen or antibody species. Strong adhesive forces were present at pH values above 7.0 when the antigen was present on the PMMA substrate, and these were attributed to hydrophobic interactions between the antigen and the alkane "linker" chain attaching the amine or carboxylate group to the AFM tip. Such hydrophobic interactions were not observed with the carboxylic acid or amine/antibody combinations suggesting that the surface-linked antibody was more resistant to denaturation under higher pH. The results demonstrated the feasibility of using AFM approaches for interrogating protein grafting strategies in the fabrication of PMMA-based microsystems.     

Facile control of surface wettability in TiO2/poly(methyl methacrylate) composite films

A facile method to produce very hydrophobic surface was developed simply using the mixture of TiO(2) nanoparticles and poly(methyl methacrylate) (PMMA). When the volume ratio of TiO(2) to PMMA is between 35 vol.% and 50 vol.%, the mixture of two hydrophilic materials became very hydrophobic. Analysis of the molecular structure by infrared spectroscopy shows that the preferential orientation and attachment of a carbonyl group of a polymer molecule to the surface of TiO(2) nanoparticles play a critical role in the appearance of the strong hydrophobicity. When this composite was exposed to UV light, PMMA on the surface of the mixture film was decomposed through a photocatalytic reaction and the very hydrophobic surface turned to the superhydrophilic one. The superhydrophilic property of UV-irradiated composite lasts as long as several months. This long lasting superhydrophilicity is ascribed to the porous structure, which provides high roughness and strong capillary interaction. Easy transition from strong hydrophobicity to superhydrophilicity in TiO(2)/PMMA composites could be applied to designing high contrast hydrophilic/hydrophobic patterns.