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.

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.

DESIGN AND SYNTHESIS OF NOVEL CHIRAL IONIC LIQUIDS AND THEIR APPLICATION IN FREE RADICAL POLYMERIZATION OF METHYL METHACRYLATE

Two new chiral ionic liquids, 1 -((-)-menthoxycarbonylmethylene)-3-methylimidazolium hexafluorophosphateand 1-((-)-menthoxycarbonylmethylene)-3-hexadecylimidazolium hexafluorophosphate, were designed an d prepared. Theirchemical structures were characterized by ~1H-NMR. Reverse atom transfer radical polymerization of methyl methacrylate(MMA) in these two ionic liquids was carried out using AIBN/CuCl_2/bipy as the initiating system. The resultant well-definedpolymethyl methacrylate (PMMA) was employed as a macroinitiator to induce the atom transfer radical polymerization ofmenthyl methacrylate (MnMA) in chlorobenzene, which yielded a PMMA-b-PMnMA diblock copolymer with narrow polydispersity.

Novel ionic liquids as reaction medium for atom transfer radical polymerization of methyl methacrylate

Atom transfer radical polymerization （ATRP） of methyl methacrylate （MMA） employing ethyl 2-bromoisobutyrate （EBiB）/ CuBr as the initiating system was investigated at 50 ℃ in the absence of any additional ligand in the three room temperature ionic liquids （RTILs）, 1-methyl-imidazolium acetate （[mim][CH3COO]）, 1-methylimidazolium propionate （[mim][CH3CH2COO]） and 1-methylimidazolium butyrate （[mim][CH3CH2CH2COO]）, respectively. All the polymerization in the three RTILs proceeded in a well-controlled manner. The sequence of the apparent polymerization rate constants was kapp（[mim][CH3COO]） 〉 kapp（[mim] [CH3CH2COO]） 〉 kapp （[mim][CH3CH2CH2COO]）.

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.

THE EFFECTS OF MAGNETIC FIELD ON GRAFT COPOLYMERIZATION OF METHYL METHACRYLATE ONTO POLYVINYL ALCOHOL IN THE PRESENCE OF BENZOPHENONE DURING UV IRRADIATION

The effects of magnetic field on the graft ratio and stereoregularity of grafts of PVA-g-MMA in the presence ofbenzophenone during UV irradiation are discussed. By means of IR, it was found that the graft ratio was increased with the increment of magnetic field strength. Furthermore, application of relative weak magnetic field of 0.4 Tesla had been shown to substantially enhance the stereo-regularity of graft copolymer. The maximum stereo-regularity appeared when the graft ratio approached to 85% with the magnetic field of 1.2 Tesla (T). The resistance to moisture and heat resistance of the grafted copolymer in the presence of magnetic field were also improved.

MEASUREMENTS OF MONOMER REACTIVITY RATIOS FOR COPOLYMERIZATION OF STYRENE AND METHYL METHACRYLATE IN CARBON DIOXIDE AT VAPOR-LIQUID EQUILIBRIUM STATE

The monomer reactivity ratios of free radical copolymerization of styrene and methyl methacrylate in carbon dioxide at vapor-liquid equilibrium state (vlCO(2)) at 65 degrees C and under 7.5-8.5 MPa were measured. The experimental results showed that, in comparison with the data in bulk copolymerization, the monomer reactivity ratio of St in vlCO(2) increased acompanied by a somewhat decrease in that of MMA. Further analysis of the sequence distributions of these copolymers by H-1-NMR spectra indicated that there was a significant bootstrap effect in this system. The local monomer concentrations in the proximity of growing free radicals, rather than the true reactivity of monomers or free radicals, were altered by the presence of vlCO(2), leading to the change in monomer reactivity ratios.

EFFECT OF TEMPERATURE ON COPOLYMERIZATION PARAMETERS OF HYDROXYETHYL ACRYLATE AND METHYL METHACRYLATE

The copolymerization of 2-hydroxyethyl acrylate (HEA, M//1) and methyl methacrylate (MMA, M//2) in cyclohexanone was studied. The multiple experiments of solution copolymerization with low conversion were carried out at two sensitive composition feed points at 60, 80, 100, 120 and 140 degree C, respectively. The composition of the copolymers was analyzed by **1H-NMR. The reactivity ratios which were estimated by the Error-in-Variable Method (EVM) of Mayo-Lewis equation were found to be r//1 equals 0.328, r//2 equals 1.781 for 60 degree C; 0.375, 1.709 for 80 degree C; 0.406, 1.654 for 100 degree C; 0.439, 1.540 for 120 degree C and 0.455, 1.400 for 140 degree C, and the 95% joint confidence intervals of the reactivity ratios were also determined. According to r//1 and r//2, Arrhenius relations and the activity energy difference between the homo- and cross-propagation were calculated. (Author abstract) 12 Refs.

Copolymerization of Dimethylaminoethyl Methacrylate and Methyl Methacrylate Catalyzed by Substituted Indanyl Lanthanide(Ⅱ) Complexes

The substituted indenyl lanthanide(Ⅱ) complexes as single component catalyzed for the copolymerization of dimethylaminoethyl methacrylate and methyl methacrylate were studied. The results indicate that these complexes all show good catalytic activity and the catalytic activity is affected by the temperature and time of polymerization, amount of catalyast and the solvent as well. The yields of the copolymerization are not affected by the ratio of monomers at all. In order of catalytic activity of the substituted indenyl lanthanide(Ⅱ) complexes: (C_5H_9C_9H_6)_2Sm(THF)>(C_2H_5C_9H_6)_2Sm(THF)_2>(C_5H_9C_9H_6)_2Yb(THF)_2>KSm(C_5H_9C_9H_6)_3(THF)_3>(PhCH_2C_9H_6)_2Sm(THF)_2. The reactivity ratio of the copolymerization of dimethylaminoethyl methacrylate and methyl methacrylate catalyzed by the substituted indenyl lanthanide (Ⅱ) complex (C_5H_9C_9H_6)_2Yb(THF)_2 (r_1=0.98, r_2=0.71) were measured.

Kinetics and Mechanism of the Polymerization of Methyl Methacrylate in a Y(acac)_3/n-BuMgCl System

Based on the kinetics equation proposed by T. Kagiya, the kinetic study on the polymerization of methyl methacrylate(MMA) by Y(acac)_3/n-BuMgCl was carried out with a dilatometer. It was found that the rate of propagation is the first order with respect to the concentration of both active center and monomer. Thus, the equation of propagation rate can be described as R_p=K_p[c][M]. In addition, the instantaneous chain initiation and single molecular termination were concluded for the present system. The activation energy is close to 32 kJ/mol. In the polymerization, n-BuMgCl acts not only as the cocatalyst, but also as chain transfer agent with c_I=3. 6 × 10^(-4).

THE EFFECTS OF N-2-HYDROXYETHYL-N-METHYL-p-TOLUIDINE ON METHYL METHACRYLATE RADICAL POLYMERI-ZATION AND ACRYLONITRILE PHOTOINDUCED POLYMERIZATION

The effects of N-2-hydroxyethyl-N-methyl-p-toluidine (HMT) on MMA polymerization using organic peroxide as an initiator and on AN photoinduced polymerization have been investigated respectively. The kinetics of polymerization and the overall activation energy of polymerization were determined. Based on kinetics study and the end group analysis of the polymer obtained by UV spectrum method, the initiation mechanism is proposed.

The Polymerization of Methyl Methacrylate in the Presence of a New Homogeneous Yttrium Catalyst

Methyl methacrylate(MMA) polymerized in the presence of a new homogeneous catalyst of Y(acac)3-(i-Bu)3Al-BuLi. The effects of MMA/Y, Al/Y, Li/Y molar ratios, polymerization temperature and time are reported. The results show that a small amount of butyl lithium could greatly enhance the activity of the catalyst and the polymerization reaction could be carried out at low temperatures (-25℃-10℃) with a high conversion. 200 kg of poly(methyl methacrylate) (PMMA) with 63% syndiotacticity could be prepared by using 1 mole of yttrium.

Atom Transfer Radical Polymerization of Methyl Methacrylate in [Hmim][HCOO]/THF Mixtures

The atom transfer radical polymerization （ATRP） of methyl methacrylate （MMA） employing ethyl 2-bromoisobutyrate （EBiB）/CuBr as the initiating system was analyzed at 30, 40, 50 and 60 ℃ in N-methylimidazolium formate （[Hmim][HCOO]）/THF mixtures. The polymerization was performed in a well-controlled manner as evidenced by kinetic study and the chain extension result. The apparent activation energy and the enthalpy of equilibrium for the preequilibrium were also investigated. Results show that Ea（app）=47.86 kJ/mol, △Heq^0=25.67 kJ/mol.

KINETICS OF POLYMERIZATION OF METHYL METHACRYLATE INITIATED BY COPPER POLYPROPYLENE-BASED POLYAMIDOXIME-SODIUM SULFITE SYSTEM~*

The aqueous polymerization of methyl methacrylate initiated by copper polypropylene-based polyamidoxime (PPAO-Cu) -sodium sulfite system was investigated. The overall rate of polymerization (R_p) isR_p=9.7 x 10^(12) e^(-21.200/RT) [MMA]^(O.88)[Na_2 SO_3]^(0.50) The length of the induction period (τ) is inversely proportional to the concentration of sodium sultite and independent of the amount of polymer supported copper and the concentration of monomer. It could be expressed as follows:1/τ =1.2x10^(12)e^(-15.600/RT)[Na_2SO_3]=K_τR_iThe polymerization is initiated by a primary radical generated from the redox reaction rather than induced by 'coordination-proton transfer' mechanism.

Microemulsion Polymerization of Methyl Methacrylate

The microemulsion polymerization of methyl methacrylate was studied. The effects of feeding modes on the structure and the properties of the obtained polymer microlatex were investigated by measuring the conversion, the transmittance and the refractive index of the latex, and by measuring the particle size, the molecular weight and the glass transition temperature (T_g) of the polymers. The results show that compared to the batch feeding mode, the semi-continuous feeding mode is more favorable to form a PMMA microlatex with a higher transmittance, a smaller particle size, a higher molecular weight and a higher T_g. And the obtained PMMA microlatex has a 30%—40% (mass fraction) polymer content, a 0. 03 emulsifier/water weight ratio, a 0. 05 emulsifier/monomer weight ratio and a 17 nm average particle diameter, which is very important for the industrialization of the microemulsion polymerization technique.

POLYMERIZATION OF METHYL METHACRYLATE CHIRAL LIGANDS

Methyl methacrylate was anionically polymerized in the presence of chiral ligands,e.g.(+)-DDB and(-)-Sp.The polymers thus formed were optically inactive due to the instability of the helical chain for the less bulky ester group.Isotactic poly(methyl methacrylate)was given when(+)-DDB was used,whereas,a syndiotactic polymer was formed in the presence of(-)-Sp.Accordingly,two different propagation mechanisms were postulated.

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.