Polybutylacrylate/poly(methyl methacrylate) Core-Shell Elastic Particles as Epoxy Resin Toughener: Part I Design and Preparation

Polybutylacrylate (PBA)/poly(methyl methacrylate) (PMMA) core-shell elastic particles (CSEP), whose rubbery core diameter ranged from 0.08 μm to 1.38μm, were synthesized by using conventional emulsion polymerization, multi-step emulsion polymerization, and soapless polymerization. Allyl methacylate (ALMA) and ethylene glycol dimethacrylate (EGDMA) were selected as crosslinking reagents for core polymerization. Methacrylic acid (MAA) was used as functional co-monomer with methyl methacrylate as shell component. The content of vinyl groups in PBA rubbery core increased with the amount of crosslinking reagents. The core-shell ratio affected great on the morphology of the complex particles. Furthermore, the amounts of carboxyl on the surface of core-shell particles, copolymerized with acrylic acid, were determined by potentiometric titration. Results showed that methylacrylic acid was distributed mostly on the surface of particles.

AN ATOMIC FORCE MICROSCOPY STUDY ON THE AGGREGATION OF ISOTACTIC POLY(METHYL METHACRYLATE)

Aggregation process of isotactic poly（methyl methacrylate） （i-PMMA） has been studied extensively for many years, and considerable progress has been made in both experimental and theoretical studies. They are, however, seldom sustained by real-space observations of the underlying morphology. In this paper, the aggregation process of i-PMMA in concentrated acetone solutions and the fractal structure of the resulting three-dimensional clusters were characterized on the basis of real-space AFM observations of their two-dimensional projection. It was found that spherical multiple-chain particles formed upon collapse and aggregation of the involving chains as a whole during quenching the solution to room temperature. By keeping the solution at room temperature, the initially formed particles stick together upon contact to form larger particles through reassembling very slowly. The succeeding collision of the enlarged spherical particles leads to the formation of small clusters. These newly formed small clusters grow when they meet with other clusters or single Brownian particles. This leads to the formation of large clusters with fractal dimension of 1.95 ± 0.05, which suggest a reaction-limited cluster aggregation of i-PMMA in a concentrated acetone solution. This is in accordance with the conclusion obtained by light scattering measurements.

Synthesis of Comblike Poly(methyl methacrylate) by Atom Transfer Radical Polymerization with Poly(ethyl 2-bromoacrylate) as Macroinitiator

Comblike poly(methyl methacrylate) was synthesized by atom transfer radical polymerization of methyl methacrylate with poly(ethyl 2-bromoacrylate) as a macroinitiator, which was prepared by conventional free radical polymerization of ethyl 2-bromoacrylate. The obtained comblike polymers were characterized by GPC and 1H NMR.

Effect of Low-Pressure Nitrogen DC Plasma Treatment on the Surface Properties of Biaxially Oriented Polypropylene, Poly (Methyl Methacrylate) and Polyvinyl Chloride Films

In this study, commercial biaxially oriented polypropylene （BOPP）, polyvinyl chlo- ride （PVC） and poly （methyl methacrylate） （PMMA） films were treated with nitrogen plasma over different exposure times in a Pyrex tube surrounded by a DC variable magnetic field. The chemi- cal changes that appeared on the surface of the samples were investigated using Fourier transform infrared （FT4R） spectroscopy and attenuated total reflectance Fourier transform infrared （ATR- FTIR） spectroscopy after treatment for 2 min, 4 min and 6 rain in a nitrogen plasma chamber. Effects of the plasma treatment on the surface topographies and contact angles of the untreated and plasma treated films were also analyzed by atomic force microscopy （AFM） and a contact angle measuring system. The results show that the plasma treated films become more hydrophilic with an enhanced wettability due to the formation of some new polar groups on the surface of the treated films. Moreover, at higher exposure times, the total surface energy in all treated films increased while a reduction in contact angle occurred. The behavior of surface roughness in each sample was completely different at higher exposure times.

PREPARATION OF POLY(METHYL METHACRYLATE)/LAYERED DOUBLE HYDROXIDES NANOCOMPOSITES via in situ SOLUTION POLYMERIZATION

An exfoliated layered double hydroxides/poly（methyl methacrylate） （LDHs/PMMA） nanocomposite was prepared by in situ solution polymerization of methyl methacrylate （MMA） in the presence of 4-vinylbenzenesulfonate intercalated LDHs（MgAl-VBS LDHs）. MgAl-VBS LDHs was prepared by the ion exchange method, and the structure and composition of the MgAl-VBS LDHs were determined by X-ray diffraction （XRD）, infrared spectroscopy and elemental analysis. XRD and transmission electron microscopy （TEM） were employed to examine the structure of LDHs/PMMA nanocomposite. It was indicated that the LDHs layers were well exfoliated and dispersed in the PMMA matrix. The grafting of PMMA onto LDHs was confirmed by the extraction result and the weight fraction of grafted PMMA increased as the weight fraction of LDHs in the nanocomposites increased.

Antibiotic-free antimicrobial poly (methyl methacrylate) bone cements:A state-of-the-art review

Prosthetic joint infection(PJI)is the most serious complication following total joint arthroplasty,this being because it is associated with,among other things,high morbidity and low quality of life,is difficult to prevent,and is very challenging to treat/manage.The many shortcomings of antibiotic-loaded poly(methyl methacrylate)(PMMA)bone cement(ALBC)as an agent for preventing and treating/managing PJI are well-known.One is that microorganisms responsible for most PJI cases,such as methicillin-resistant S.aureus,have developed or are developing resistance to gentamicin sulfate,which is the antibiotic in the vast majority of approved ALBC brands.This has led to many research efforts to develop cements that do not contain gentamicin(or,for that matter,any antibiotic)but demonstrate excellent antimicrobial efficacy.There is a sizeable body of literature on these socalled“antibiotic-free antimicrobial”PMMA bone cements(AFAMBCs).The present work is a comprehensive and critical review of this body.In addition to summaries of key trends in results of characterization studies of AFAMBCs,the attractive features and shortcomings of the literature are highlighted.Shortcomings provide motivation for future work,with some ideas being formulation of a new generation of AFAMBCs by,example,adding a nanostructured material and/or an extract from a natural product to the powder and/or liquid of the basis cement,respectively.

Effect of catalyst on formation of poly(methyl methacrylate) brushes by surface initiated atom transfer radical polymerization

Poly （methyl methacrylate） （PMMA） brushes were synthesized from silicon wafers via surface initiated atom transfer radical polymerization （SI-ATRP）. Energy disperse spectroscopy （EDS） and atomic force microscopy （AFM） confirmed that PMMA brushes were successfully prepared on the silicon wafers, and the surface became more hydrophobic according to the contact angle of 69~. It is found that CuCI/1, 1, 4, 7, 10, 10-hexamethyl triethylenetetramine （HMTETA） system is more suitable than CuBr/N, N, N′, N″, N′″-pentamethyl diethylenetriamine （PMDETA） system to control the free radical polymerization of MMA in solution. Nevertheless, better control on the thickness of PMMA brushes was achieved in CuBr/PMDETA than in CuC1/HMTETA due to higher activity and better reversibility of the former system.

MECHANICAL PROPERTIES OF CARBON/GLASS FIBER REINFORCED POLY(METHYL METHACRYLATE)COMPOSITES

Artificial bone, carbon/glass fiber reinforced PM-MA composites have been prepared by hot press moulding of pre-preg -which monofilments of CF and GF impregnated by MMA prepolymer. When the PMMA volume fraction in com-posites is 50% > theoretical and experimental results show that strength and modules of these hybrid composites are in accord with 'rule of mixture'. The tensile and flexure strength are the lowest when the raletive volume fraction of carbon fiber in rein-forcements is 50%,SEM examinations further explained re-sults.

Synthesis and characterization of poly(methyl methacrylate-co-polyhedral oligomeric silsesquioxane)hybrid nanocomposites

A novel poly（methyl methacrylate-co-polyhedral oligomeric silsesquioxane） hybrid nanocomposite was synthesized by free radical polymerization and characterized by 1H NMR, 29Si NMR, and TGA technologies. Compared with PMMA homopolymer, the nanocomposite has better thermal stability.

Photochemical kinetics for holographic grating formation in phenanthrenequinone doped poly (methyl methacrylate) photopolymer

The photochemical kinetics of phenanthrenequinone （PQ） doped poly （methyl methacrylate） photopolymer in holographic recording was studied theoretically and experimentally. The diffusion of PQ molecules during holographic recording was negligible because of its small diffusion coefficient at room temperature. A photochemical reaction kinetics model of PQ/PMMA was established. The analytical expressions for the temporal variations of transmittance and diffraction efficiency were derived. By fitting the experimental curves, some parameters related with the polymer components were obtained by the proposed model, which can be used to analyze the photochemical process and will be helpful to the optimization of material preparation.

COMPATIBILITY IN POLYMER BLENDS OF POLY (VINYL ACETATE) AND POLY (METHYL METHACRYLATE)STUDIED BY NMR

Compatibility of poly (vinyl acetate) (PVAc) with poly (methyl methacrylate) (PMMA) mixtures has been studied by using nuclear magnetic relaxation, differential scanning calorimeter and small-angle X-ray scattering techniques. The nuclear magnetic relaxation time T_1's were measured as a function of composition in blends of PMMA and PVAc prepared from chloroform solution. The results show that the system is miscible for casting from chloroform solution.

Grafted Deproteinized Natural Rubber as an Impact Modifier in Styrene-Methyl Methacrylate Copolymer Sheet

This research was studied to prepare styrene-methyl methacrylate copolymer sheet （S-co-MMA sheet） by using DPNR （deproteinized natural rubber） as an impact modifier. The DPNR was prepared by adding SDS （sodium dodecyl sulfate） into the HANR （high-ammoniated natural rubber latex） and followed by centrifugation. It was found that DPNR was successfully prepared with the lowest nitrogeneous content about 0.034±0.01% w/w by adding SDS for 1.00 phr and centrifugation at 12,000 rpm. Then DPNR was grafted with styrene and methyl methacrylate （DPNR-g-S/MMA） obtained by emulsion polymerization. The effects of DPNR-g-S/MMA were studied by varied the amount of SDS and redox initiator. From this result the grafting efficiency DPNR-g-S/MMA was higher than that of NR-g-S/MMA. The DPNR-g-S/MMA was used as an impact modifier in S-co-MMA sheet. Furthermore, the appropriate quantities of styrene monomer and DPNR-g-S/MMA were also investigated. While DPNR-g-S/MMA was used as impact modifier in S-co-MMA sheet, the result was shown DPNR-g-S/MMA improve impact strength of S-co-MMA sheet. Scanning electron micrographs of S-co-MMA sheet with DPNR-g-S/MMA was found the smooth fracture surface. Thus impact strength of S-co-MMA/gDPNR sheet was high and physical properties of S-co-MMA/gDPNR sheet could be able to be accepted in industry. Concisely, DPNR-g-S/MMA can be used as an impact modifier in S-co-MMA sheet.

Stereocomplex Formation of Atactic Poly(methyl mcthacrylate)

Stereocomplexes formed in atactic poly(methyl methacrylatc) (α-PMMA) films cast form different solvents were studied by means of Fourier transform infrared spectroscopy (FTIR). and differential scanning calorimetry (DSC). The growth of stereocomplex was a function of annealing temperature and annealing time. respectively.

A novel method for fabricating polydimethylsiloxane microfluidic chip master molds

We proposed a novel method of fabricating polydimethylsiloxane (PDMS) microfluidic chip polymer master molds in this paper. The method mainly includes two steps. First, a stainless steel slice was laser etched to form a metal model. Then, the organic solution of poly(methyl methacrylate) (PMMA) was casted onto the metal model to fabricate the PMMA master which subsequently would be used to fabricate PDMS chips. We systematically researched different laser parameters influencing the surface status of microchannels and obtained optimized etching parameters. We investigated and optimized the organic solution composition of PMMA while casting chip masters, and developed a method to form fine polymer masters using two different viscosity solutions to cast the model in turn, and studied the repeatable replication. Then, we investigated physical performance of this chip and evaluated the practicability by analyzing Rhodamine B. Compared with present methods, the proposed method does not need photolithography on photoresistant and chemical etching. The entire fabricating progress is simple, fast, low-cost and can be controlled easily. Only several minutes are required to make a metal model, 3 hours for a PMMA master, and one day for PDMS chips.

Structure Characterization and Thermal Properties of PMMA/Montmorillonite Nanocomposites via Emulsion Polymerization

Montmorillonite(MMT) modified with sodium silicate can change the arrangement of its layers from edge-face and edge-edge to face-face. With the fine dispersion of the modified MMT in water,the cation-exchange reaction was carried out with cetyltrimethyl ammonium bromide(CTAB) to obtain organo-montmorillonite(OMMT). As OMMT was uniformly dispersed in methyl methacrylate(MMA) monomer,PMMA/OMMT nanocomposites were formed via a common emulsion polymerization. The products were extracted with hot acetone and characterized by FTIR,molecular weight,X-ray diffraction(XRD),transmission electron microscopy(TEM),DSC and TGA. These results show that most of the OMMT layers have been exfoliated,while the thermal stability is increased obviously. By means of FTIR spectral analysis,the ratios of the macromolecular radicals′ termination of disproportionation patterns to combination are increased with the addition of OMMT. This result further confirms the increase of the thermal degradation temperatures and glass transition temperatures of the PMMA/OMMT nanocomposites.

PHOTOCHROMISM AND LUMINESCENCE OF DOPANT CHROMOPHORES THROUGH TWO-PHOTON IONIZATION IN POLYMER FILMS

Two-photon ionization and recombination processes of an aromatic chromophore doped in polymer films werestudied and the features of these processes were discussed in relation to photofunctional polymers, An aromatic moleculehaving low ionization potential, e.g., N,N,N',N'-tetramethyl-p-phenylene diamine doped in poly(methyl methacrylate)(PMMA) film was easily photoionized by intense laser ligh excitation, giving a colored radical cation (photochromism) anda trapped electron in PMMA matrix. As a reversed process, the radical cation recombined with the trapped electron, showingdiscoloration and emitting luminescence, either isothermal luminescence (ITL), or thermoluminescence (TL). In this report,ITL and TL through the charge recombination process were studied and the luminescence was suggested as a mean of the read-out of photorecording.

Preparation of Smart Fluid from Polymer Coated Pumice Particles

This study reports, electrorheological (ER) responses of pumice and poly(methyl methacrylate)/ pumice, PMMA/pumice, conducting composite dispersions in silicone oil (SO). Primarily three different compounds (K1, K2, K3, 73%, 48%, 22% contain pumice particles) PMMA/pumice composites were prepared and used as ER active materials. Anti-sedimentation stabilities of pumice and composite systems in silicone oil (SO) medium were determined. The application of a suspension of composite particles as an electrorheological ER fluid (20% particle concentration) was assessed using a rotational electro-rheometer, and the effects of the electric field strength, shear rate, frequency and temperature were examined. ER activity of all the composite suspensions was observed to increase with increasing concentration, electric field strength and decreasing shear rate. The PMMA/pumice composites suspensions show a typical shear thinning non-Newtonian viscoelastic behavior, in which viscosity of the suspension decremented sharply with incrementing shear rate. The ER measurement results showed that the performance of the composite suspensions was enhanced by increasing the electric field strength.

Preparation and Characterization of High Content Paraffin Wax Microcapsules and Micro/Nanocapsules with Poly Methyl Methacrylate Shell by Suspension-Like Polymerization

The suspension-like polymerization method is used to obtain poly methyl methacrylate （PMMA）/paraffin wax microcapsules and micro/nanocapsules with high core content. Particle size distribution （PSD） analysis indicates that the average particle size of microcapsules is 94 μm, and the size of micro/nanocapsules ranges in 0.1-19 μm. Differential scanning calorimetry （DSC） and thermalgravimetric analysis （TGA） results show that the fabricated paraffin contents in microcapsules and micro/nanocapsules are as high as 89.5 wt% and 80~2 wt%, respectively with good thermal stability. Thermal cycling tests justify that both the microcapsules and micro/nanocapsules have good thermal reliability with respect to the changes in their thermal properties after 1000 thermal cycling. This work pro- vides a novel method to prepare microcapsules and micro/nanocapsules with high core content which may benefit further study on thermal energy storage.

Modification on crystallization of poly（vinylidene fluoride） （PVDF） by solvent extraction of poly（methyl methacrylate） （PMMA） in PVDF/PMMA blends

The crystallization modification of poly（vinylidene fluoride） （PVDF） was investigated for the blend films of PVDF and poiy（methyl methacrylate） （PMMA）. The mass crystallinity （Xc） and further, the β-phase content （F（β）） of PVDF, were studied for the asprepared blend films with different mass ratios. In addition, the variations of Xc and F（β） were systematically probed once the PMMA component was removed from the related blend systems. DSC, FTIR and XRD measurements all indicated that 1）Xc, F（β） and even the content of a-phase （F（a）） decreased with the addition of PMMA; 2） with the extraction of PMMA, both Xc and F（β） increased while F（a） decreased. It is worth noting that the increase of Xc and F（β） depended on the relative amount of extracted PMMA （EpMMA）, i.e., the more PMMA was removed, the more Xc and F（β） increased. These results reveal the hindrance effect from the PMMA constituent to the crystallization of PVDF, and consequently, this restriction would be released when the PMMA was extracted.

Surface Characterization and Tribology Behavior of PMMA Processed by Excimer Laser

Polyoxymethylene methacrylate (PMMA) is widely used in ophthalmic biomaterials. Misuse of PMMA in extreme environments is likely to damage the ocular surface and intraocular structures. The surface characterization and tribological behavior of PMMA processed using an excimer laser were investigated in this study by contrasting diferent lubrication conditions and friction cycles. The results show that the roughness of the material surface increases with laser processing, which changes its physical structure. Under lubrication, the laser-treated PMMA exhibits better hydrophilicity, especially during the use of eye drops. No obvious relationship exists between the laser-processing time and friction behavior. However, the laser treatment may contribute to the formation of friction and wear mechanisms of PMMA materials. Laser-treated PMMA in saline solution exhibits better abrasive resistance by showing a lower wear rate than that in eye drops, although it has a higher friction coefcient. In this study, the diferent friction stages in laser-treated PMMA were clarifed under two lubrication conditions. The wear rates of the laser-treated PMMA were found to decrease with the number of cycles, and the friction coefcient has a similar variation tendency. The wear behavior of the laser-treated PMMA is dominated by the main abrasive wear and secondary transferred flm formation. This study provides a theoretical basis for the development and application of ophthalmic biomaterials in complex environments by examining the material surface interface behavior and wear mechanism after laser processing using PMMA as the research matrix.