Graft Polymerization Of Methacrylic Acid Research Articles

Imparting ion-exchange properties to fibrous polycaproamide materials by chemically initiated graft copolymerization

The study of the types and properties of surgical threads, as well as the experience in the production of suture surgical material and its use shows that the most promising for surgical practice are threads with antimicrobial properties. Of the methods for fixing medicinal compounds with chemical bonds for suture materials, the most expedient is their attachment by the reaction of ion-exchange interaction. Since polycaproamide (PCA) practically does not contain functional groups, a preliminary modification stage is required to impart ion-exchange properties to PCA fibrous materials. One of these stages of modification is the process of graft polymerization of methacrylic acid (MAA) in order to create active groups on the fiber, for example, peroxide or hydroperoxide. Modification of chemical fibers by graft copolymerization with inogenic monomers is one of the widespread methods of obtaining fibrous ion exchangers. Principles, new approaches and technologies for imparting ion-exchange properties to fibrous polycaproamide materials by chemically initiated graft copolymerization have been developed. Regularities in the production of fibrous PCA of sorption active materials by chemical initiation by a redox system (Fe2++H2O2) located in a modifying bath, as well as by pre-oxidation of fiber PCA in order to create peroxide and hydroperoxide groups on the fiber, are revealed.

Microfibrillated Cellulose Grafted with Metacrylic Acid as a Modifier in Poly(3-hydroxybutyrate)

This work proposes a new method for obtaining poly(3-hydroxybutyrate) (PHB)/microfibrillated cellulose (MC) composites with more balanced properties intended for the substitution of petroleum-based polymers in packaging and engineering applications. To achieve this, the MC surface was adjusted by a new chemical route to enhance its compatibility with the PHB matrix: (i) creating active sites on the surface of MC with γ-methacryloxypropyltrimethoxysilane (SIMA) or vinyltriethoxysilane (SIV), followed by (ii) the graft polymerization of methacrylic acid (MA). The high efficiency of the SIMA-MA treatment and the lower efficiency in the case of SIV-MA were proven by the changes observed in the Fourier transform infrared FTIR spectra of celluloses. All modified celluloses and the PHB composites containing them showed good thermal stability close to the processing temperature of PHB. SIMA-modified celluloses acted as nucleating agents in PHB, increasing its crystallinity and favoring the formation of smaller spherulites. A uniform dispersion of SIMA-modified celluloses in PHB as a result of the good compatibility between the two phases was observed by scanning electron microscopy and many agglomerations of fibers in the composite with unmodified MC. The dual role of SIMA-MA treatment, as both compatibilizer and plasticizer, was pointed out by mechanical and rheological measurements. This new method to modify MC and obtain PHB/MC composites with more balanced stiffness–toughness properties could be a solution to the high brittleness and poor processability of PHB-based materials.

SENSORS BASED ON TRACK-ETCHED MEMBRANES FOR ELECTROCHEMICAL DETECTION OF CADMIUM IONS

Among electrochemical detection methods, square-wave anodic voltammetry (SW-ASV) is the most popular. However, this method has a number of limitations, for instance, mercury or bismuth electrodes are usually used as a working electrode, which are highly toxic substances. This article is devoted to the study of the use of track-etched membranes based on polyethylene terephthalate as a basis for electrochemical sensors. The modification of the surface of membranes was carried out by the method of photoinitiated graft polymerization of methacrylic acid. Magnetron sputtering with a mask was used to obtain electrodes on both sides of the membrane. The sensor has been tested for sensing toxic cadmium ions in a concentration range of 0.5 to 12.5 mg/L.

Enhancement of electrochemical detection of Pb2+ by sensor based on track-etched membranes modified with interpolyelectrolyte complexes

This article concerns studies of flexible track-etched membrane modification by photograft polymerization of methacrylic acid and subsequent formation of interpolyelectrolyte complexes with poly(allylamine) for enhancement of properties of electrochemical sensor. Optimal conditions leading to functionalization of the surface and maintenance of the pore structure were found. Membranes were characterized by SEM, FTIR, XPS, gas permeability and colorimetric assay. Square wave anodic stripping voltammetry (SW-ASV) was used for detection of Pb2+. Limits of detection (LOD) for sensors based on non-modified PET TeMs, membranes modified by graft polymerization of methacrylic acid (PET TeMs-g-PMAA) and membranes modified with interpolyelectrolyte complexes with poly(allylamine) (PET TeMs-g-PMAA-PAlAm) are 3.03, 2.78 and 1.25 µg/L, respectively. Thus, it was shown that the formation of interpolyelectrolyte complexes on the membranes leads to a more accurate detection of lead ions.

Poly (methacrylic acid) modified spherical and platelet hybrid nanoparticles as reinforcing fillers for dentin bonding systems: Synthesis and properties

In this study the mechanical and adhesion properties of an experimental methacrylate based dentin bonding system containing a combination of spherical and layered platelet nanoparticles were investigated. The nanoparticles were first modified through surface graft polymerization of methacrylic acid in order to make the particles surface compatible with the bonding matrix resin. Graft free radical polymerization in aqueous media was performed to attach Poly (methacrylic acid) (PMA) chains onto the surface of Na-MMT nanoclay (Cloisite® Na+) and silica nanoparticles (Aerosil® 200). The hybrid PMA grafted nanoparticles (PMA-g-NC-Sil) were characterized using GPC, FTIR, TGA, and X-ray diffraction (XRD). Dentin adhesives containing different amounts of the hybrid modified nanoparticles were photopolymerized and their characteristics were studied using FTIR, TEM, SEM, EDXA, and XRD techniques. The adhesives containing different amounts of PMA-g-NC-Sil were applied to the conditioned human premolar dentin to bond a dental composite to the teeth. The bond strength was then measured by microshear bond strength testing method. The results were analyzed and compared statistically. The stability of PMA-g-NC-Sil dispersion in the dentin adhesive was investigated using separation analysis (LUMi Reader) techniques. The grafting of PMA chains onto the surface of nanoclay was confirmed by FTIR and TGA analytical techniques. The intercalated-exfoliated structure for the nanoclay platelets in the photo-cured adhesive was observed using XRD and TEM. The surface modification of the nanoparticles significantly increased the dispersion stability of the fillers in the adhesive solution. The microshear test results indicated that the incorporation of the PMA-g-NC-Sil nanoparticles significantly enhanced the bond strength to dentin with the highest shear bond strength observed at 0.5wt%. The incorporation of the PMA modified hybrid nanofillers into the dentin adhesive resulted in a dentin bonding agent with enhanced shear bond strength through reinforcing the adhesive matrix and potential interactions between their carboxylic acid groups and the tooth structure. The dispersion stability of the nanoparticles was also dramatically improved by the surface modification of the nanoparticles.

Heterogeneous Functionalization of Polyethersulfone: A New Approach for pH-Responsive Microfiltration Membranes with Enhanced Antifouling Properties

In this work, 2,2’-azo-bis-butyronitrile (AIBN) was exploited as an initiator for the successful bulk heterogeneous functionalization of polyethersulfone (PES) using polymethacrylic acid (PMAA), for the first time. To this end, pH-responsive and exceptionally low fouling membranes of extremely low grafting degrees with low adhesion and high rejection of protein were fabricated. An added advantage of this method is the accomplishment of graft polymerization of methacrylic acid (MAA) in water in the absence of toxic solvents, scavengers or catalysts. Changes to surface functional groups of the PES powder were determined using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and thereafter validated with X-ray photoelectron spectroscopy (XPS). The phase inversion technique was used to fabricate microfiltration membranes (MFs), which were found to possess up to 40% improved hydrophilicity relative to pristine PES membranes. Protein adsorption was reduced by more than 80% while its rejection and the pure water permeate flux recovery ratio (FR) were 97%, and 86%, respectively. Furthermore, the membrane maintained 90% FR over 10 cycles. The newly fabricated membranes possess enhanced response to pH stimulus.

Methacrylic acid functionalized CPS microspheres to adsorb shikimic acid

Chloromethylated cross-linked polystyrene (CMCPS) microsphere is hydroxylated, obtaining hydroxylated cross-linked polystyrene microsphere (CPS-OH). Methacrylic acid (MAA) is grafted on the surface of CPS-OH microspheres by cerium salt-hydroxyl group redox initiation system, obtaining graft-polymerization functional microsphere CPS-g-PMAA. The chemical structure and physicochemistry characters of CPS-g-PMAA are characterized with infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The adsorption performance of the grafted microspheres CPS-g-PMAA for shikimic acid was mainly investigated and the adsorption mechanism was explored. The experiment results show that for the graft-polymerization of MAA, the suitable concentration of MAA in solution is 3.2 mol/L, the optimal concentration of initiator cerium salt and catalyzer Sulfuric acid is 1.3 × 10−2 and 0.3 1 mol/L, respectively, the appropriate temperature is 55 °C, and reaction time is 6 h, the grafting degree of PMAA can reach 43.3 g/100 g. The kinetics demonstrating adsorption kinetic of SA by CPS-g-PMAA is fitted PFO model in the first 50 min and is then fitted with the PSO model. The CPS-g-PMAA microsphere adsorbs SA via hydrogen bond interaction, the adsorption capacity reaches 92 mg/g in ethanol. The adsorption amount decreases with the increase of temperature, Freundlich isothermal model is fitted the adsorption experimental data.

Molecularly imprinted composite bacterial cellulose nanofibers for antibiotic release

The aim of this work is to develop drug carrier system with high loading capacity and controlled drug release profile for antibiotic release. For this purpose, composite molecularly imprinted nanofibers were prepared via in-situ graft polymerization of methacrylic acid as a monomer, N,N’-methylene bisacrylamide as a crosslinker and gentamicin sulfate as a template molecule onto surface-modified bacterial cellulose nanofibers. Gentamicin imprinted microparticles were fabricated onto bacterial cellulose nanofibers resulting in the formation of composite BC nanofibers. Thus, the composite nanofibers incorporated with gentamicin imprinted microparticles were achieved to fabricated. The in-vitro drug release tests were performed to evaluate the release performance of the resultant composite nanofibers at 37 °C. Also, kinetic models were applied to the drug release data. It was determined that the drug release from the composite molecularly imprinted nanofibers fit well in the Korsmeyer-Peppas model.

Designing and preparation of novel alkaloid-imprinted membrane with grafting type and its molecular recognition characteristic and permselectivity

A novel polysulfone-based molecularly imprinted membrane (MIM) with graft type (designated as GMIM) was successfully prepared by a combination of film-forming method of immersion–precipitation phase transformation with molecule surface-imprinting technique. The porous asymmetry membrane of chloromethylated polysulfone (CMPSF) was first prepared by a phase inversion method, and then the CMPSF membrane was amination-modified with ethanediamine as reagent, resulting aminated polysulfone membrane AMPSF, on whose surface primary amino groups were contained. Then the graft-polymerization of methacrylic acid (MAA) was realized by initiating of the surface-initiating system of –NH2/S2O8−, obtaining the grafted membrane PSF-g-PMAA. After PSF-g-PMAA membrane adsorbed matrine, the crosslinking reaction of the grafted PMAA was allowed to be carried out with ethylene glycol diglycidyl ether (EGDE) as crosslinker, resulting in the matrine imprinted membrane with graft type, GMIM. The binding characteristics of the imprinted membrane GMIM, the permeability and separation property for matrine were investigated in depth. The experimental results show that the imprinted membrane consists of a thin imprinted layer, a thin skin layer containing channels at nanoscale and a support layer with macroporous structure. The imprinted membrane GMIM has specific recognition selectivity and excellent binding affinity for matrine, and its selectivity coefficient for matrine relative to cytisine is 4.85. More importantly, the imprinted membrane can produce good “gate effect” because of its own structure characteristic, so that it has fine permselectivity for the template, matrine molecule. The separation coefficient of the imprinted membrane GMIM for matrine relative to cytisine as a contrast reaches up to 5.9, displaying the excellent performance of a selectively permeable membrane.

Surface-initiated reversible addition–fragmentation chain transfer polymerization from “clickable” polypropylene surface modified by iodine plasma activation

An iodine modified polypropylene surface was synthesized by iodine plasma activation. The obtained polypropylene surface was found to be a useful platform for secondary reactions. For instance, an azide-functionalized PP was prepared by nucleophilic exchange reaction. The surface was proven to be reactive toward R group of an alkyne modified RAFT agent via the copper-catalyzed azide–alkyne cycloaddition. RAFT mediated graft polymerization of methacrylic acid was carried out and lead to a controlled polymerization from the surface. Characterizations of the modified surface and the grafted polymers were performed through FTIR-GATR, XPS, AFM and colorimetric assays.

Fouling and rejection behavior of carbon nanotube membranes

In recent years, there has been a growing interest in nanostructure membranes made of vertically aligned carbon nanotubes (VA-CNT) due to their potential of high water permeability. Nevertheless, membrane fouling is one of the most critical issues in these VA-CNT membranes. Accordingly, this study mainly focused on understanding of membrane fouling of VA-CNT membranes, which were prepared by thermal chemical vapor deposition (CVD) technique. Surface modification by graft-polymerization of methacrylic acid (MA) was attempted to not only retard membrane fouling but also improve solute rejection. The resistance-in-series model was applied to characterize the properties of fouling layers. BSA (bovine serum albumin) was used as the model foulant. Results indicated that the VA-CNT membranes had higher fouling propensity than polymeric membranes. After surface modification, however, irreversible fouling was significantly reduced in the VA-CNT membranes, which was attributed to an increase in hydrophilicity and surface charge. The rejection of BSA by VA-CNT membrane also increased after surface modification, suggesting that the surface charge played an important role in the rejection of charged molecules.

Multifunctional terpolymeric MRI contrast agent with superior signal enhancement in blood and tumor

A new multifunctional terpolymeric system for simultaneous imaging and drug delivery has been recently developed in our laboratory. Herein we report the investigation of terpolymeric contrast agent for magnetic resonance imaging and doxorubicin (Dox) delivery. The polymer was synthesized by graft polymerization of methacrylic acid (MAA) and polysorbate 80 (PS 80) onto starch with multiple, chemically bound diethylenetriaminepenta acetic acid (DTPA) groups for gadolinium chelating. The terpolymer self-assembled to form nanoparticles upon addition of doxorubicin which binds with the PMAA chain. The physicochemical, biological and pharmacokinetic properties of the polymeric system were characterized and their contrast enhancement capability was evaluated in vitro and in vivo. The polymer was able to load gadolinium with high thermodynamic stability and exhibited low cytotoxicity. The Gd-loaded polymer (PolyGd), and Gd-Dox co-loaded nanoparticles (PolyGd-Dox) significantly enhanced MR signals, with ionic T1 relaxivities 3–5 times higher than those from Omniscan®, a small molecule contrast agent. In vivo studies showed superior and prolonged contrast enhancement compared to Omniscan® at one fourth the equivalent dose, without adverse effects. The PolyGd and PolyGd-Dox accumulated in the tumor and painted the tumor boundaries clearly for at least 48h. The PolyGd also enhanced angiogram contrast with contrast to noise ratio values of up to 55-fold and a blood half-life time of 200min. Seven days after intravenous administration, only relatively small amounts of gadolinium could be detected in the major organs of the mice (supplementary materials). These results suggest that the new terpolymeric system is useful as a theranostic platform for contrast enhanced MR imaging of vasculature and tumor as well as Dox delivery.

THROMBIN IMMOBILIZATION TO METHACRYLIC ACID GRAFTED POLY(3-HYDROXYBUTYRATE) AND ITS IN VITRO APPLICATION

Poly(3-hydroxybutyrate) is nontoxic and biodegradable, with good biocompatibility and potential support for long-term implants. For this reason, it is a good support for enzyme immobilization. Enzyme immobilization could not be done directly because poly(3-hydroxybutyrate) has no functional groups. Therefore, modification should be done for enzyme immobilization. In this study, methacrylic acid was graft polymerized to poly(3-hydroxybutyrate) and thrombin was immobilized to polymethacrylic acid grafted poly(3-hydroxybutyrate). In fact, graft polymerization of methacrylic acid to poly(3-hydroxybutyrate) and thrombin immobilization was a model study. Biomolecule immobilized poly(3-hydroxybutyrate) could be used as an implant. Thrombin was selected as a biomolecule for this model study and it was immobilized to methacrylic acid grafted poly(3-hydroxybutyrate). Then the developed product was used to stop bleeding.

Constituting redox initiation system of mercapto-cerium salt and realizing highly effective graft-polymerization of MAA on surfaces of silica gel particles

In this work, a new and highly efficient method of surface-initiated free radical graft-polymerizations on the surfaces of silica gel particles was put forward, and the graft-polymerization of methacrylic acid (MAA) was conducted. This method was convenient, feasible and highly effective. Coupling agent γ-mercaptopropyltrimethoxysilane(MPTS) was first bonded onto the surfaces of silica gel particles, obtaining the modified particles MPTS-SiO2, onto which mercapto groups were chemically attached, so a redox initiation system of graft-polymerization was constituted by the mercapto group on the surfaces of MPTS-SiO2 particles and the cerium (IV) salt in the solution. And then the surface-initiated free radical graft-polymerization of MAA on the surfaces of silica gel particles was carried out, resulting in the grafted particles PMAA/SiO2 with a very high grafting density (35 g/100 g) of PMAA. The grafted particles PMAA/SiO2 were characterized by infrared spectrum (FTIR), scanning electron microscope (SEM) and thermogravimetric analysis (TGA). The effects of the main factors on the new surface-initiated graft polymerization were emphatically examined, and the corresponding mechanism of the graft-polymerization was investigated in depth. The experimental results show that the mercapto group-cerium salt system analogous to the hydroxyl group-cerium salt system, can also effectively initiate vinyl monomers to be graft-polymerized on the surfaces of solid particles, and furthermore, it is a highly effective surface-initiated graft-polymerization method. In this graft-polymerization system, several factors such as sulfuric acid concentration, the used amount of cerium salt and the reaction temperature affect the grafting density greatly. For the graft-polymerization of MAA, the appropriate reaction conditions are as follows: reaction time of 3 h, reaction temperature of 50 °C, cerium concentration of 5.0 × 10−3 M, acid (H+ ion) concentration of 0.15 M and MAA concentration of 0.5 M.

Evaluation of new bi-functional terpolymeric nanoparticles for simultaneous in vivo optical imaging and chemotherapy of breast cancer.

Successful development of a nanoparticulate system for cancer chemotherapy requires detailed knowledge of its biodistribution, clearance and anti-tumour efficacy in vivo. Herein we developed new bi-functional nanoparticles for simultaneous in vivo optical imaging and delivery of the anticancer drug doxorubicin (Dox) for enhanced chemotherapy. Two types of nanoparticles were synthesized, namely preformed nanoparticles (PF-NPs) and self-assembled nanoparticles (SA-NPs). The PF-NPs were prepared by cross-linking graft polymerization of methacrylic acid and polysorbate 80 with starch (PMAA-PS 80-g-St) and then loading the particles with Dox. The SA-NPs were formed upon addition of Dox to non-cross-linked PMAA-PS 80-g-St. A near infrared fluorescent probe was conjugated with the PMAA unit of the nanoparticles. The biodistribution, tumour targeting and pharmacokinetics of the Dox-loaded nanoparticles in mice were determined by in vivo/ex vivo fluorescence imaging and ex vivo fluorescence microscopy. The anti-tumour efficacy of the nanoparticles was investigated using a murine orthotopic breast cancer model. PF-NPs had an average hydrodynamic diameter and zeta potential of 137 ± 3nm and -38 ± 1mV, respectively. These values were measured at 62 ± 5nm and -35 ± 5mV for SA-NPs. PF-NPs exhibited a porous morphology while the SA-NPs appeared to have a denser structure. SA-NPs outperformed the PF-NPs in terms of blood circulation, tumour uptake and penetration. PF-NPs and SA-NPs exhibited no systemic toxicity and inhibited tumour growth significantly better than the free Dox solution with SA-NPs being the best, attributable to their excellent tumour uptake and penetration. This work demonstrates the usefulness of these bi-functional nanoparticles as nanotheranostics.

Preparation of Grafted SiO2-g-PMAA Particles with High Grafting Degree via a Surface-initiated Graft Polymerization Method

Coupling agent γ-aminopropyltrimethoxysilane (AMPS) was firstly bond onto the surface of silica gel particles forming modified AMPS-SiO2 particles. With the presence of ammonium persulphate in the solution, a redox initiating system was then achieved and allowed the surface-initiated graft polymerization of methacrylic acid (MAA) on the silica gel particles with a high grafting degree (0.30 g/g). The effects of different factors on the whole process were investigated in depth. The experimental results show that an optimal temperature for the surface-initiated graft polymerization system is 40℃. At higher temperature, the graft degree will decline due to the heat decomposition of ammonium persulphate. In addition, the grafted polymer layer hinders further polymerization. The appropriate reaction conditions are: 1.1% of the initiator and nearly 5% of the monomer concentration.

Colon-specific drug delivery behavior of pH-responsive PMAA/perlite composite.

The preparation, characterization, and in vitro release of 5-aminosalicylic acid (5-ASA) from methacrylic acid (MAA)/perlite composites (APC) prepared via a sol–gel route are reported. The free-radical graft polymerization of methacrylic acid (MAA) onto perlite particles was studied experimentally. The grafting procedure consisted of surface activation with 3-(trimethoxysilyl) propyl methacrylate (TSPA), followed by free-radical graft polymerization of methacrylic acid (MAA) in ethyl acetate with 2,2′-azobisisobutyronitrile (AIBN) initiator. The composition of the composites hybrid materials was determined by FTIR spectroscopy. Equilibrium swelling studies were carried out in enzyme-free simulated gastric and intestinal fluids (SGF and SIF, respectively). The dried composites were immersed in a saturated solution of 5-ASA in water overnight and dried over a period of three days at room temperature and the in vitro release profiles were established separately in both (SGF, pH 1) and (SIF, pH 7.4). The 5-ASA concentration of the solution was measured using a UV-Vis spectrophotometer (205 nm) at different time intervals. The in vitro drug release test revealed that the release rate of 5-ASA in buffer solutions increased with the silica content in the composites; on the contrary, the increase of the content of 3-(trimethoxysilyl)propyl methacrylate (TSPA), a coupling agent, decreased the drug release rate.

Adsorption Behavior and Mechanism of Grafted PMAA-HEMA/NVP Microspheres toward Lysozyme

采用反相悬浮聚合法制备了甲基丙烯酸羟乙酯（HEMA）与N-乙烯基吡咯烷酮（NVP）的交联共聚微球HEMA/NVP,然后采用＂接出＂法,实施了甲基丙烯酸（MAA）在交联微球表面的接枝聚合,制得了接枝微球PMAA-HEMA/NVP.以溶菌酶（LYZ）为模型碱性蛋白,深入研究了接枝微球PMAA-HEMA/NVP对碱性蛋白的吸附性能与吸附机理.测定了微球PMAA-HEMA/NVP的zeta电位,考察了PMAA接枝度、介质pH值及离子强度等因素对体系吸附性能的影响.结果表明,在较大的pH范围内,接枝微球PMAA-HEMA/NVP的zeta电位为绝对值较大的负值,即其表面携带有高密度的负电荷.在强静电相互作用的驱动下,接枝微球PMAA-HEMA/NVP对溶菌酶表现出很强的吸附能力.随介质pH值的增高,接枝微球对溶菌酶的吸附容量呈现先增大后减小的变化趋势,在与溶菌酶等电点接近的pH值处（pH=9）,具有最大的吸附容量（90mg.g^-1） 离子强度对接枝微球的吸附能力也有较大的影响,当pH〈9时,溶菌酶吸附容量随NaCl浓度的增高而减小 当pH〉9时,吸附容量随NaCl浓度的增高而增大.

Graft polymerization of methacrylic acid onto polyethersulfone for potential pH-responsive membrane materials

Facile graft polymerization of methacrylic acid (MAA) onto polyethersulfone (PES) using benzoyl peroxide (BPO) as chemical initiator had been developed. The polymerization was carried out in a heterogeneous polymer–monomer reaction system using water as reaction medium. The crucial parameters affecting the graft yield, such as monomer concentration, reaction time and temperature, were studied. The amount of grafted PMAA on PES was increased with increasing monomer concentration and reaction time. The optimum temperature for the grafting was around 75 °C. The graft polymers produced herein were cast into ultrafiltration membranes via phase inversion process. The cross-sectional morphology and surface composition of the membranes were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. Remarkable surface enrichment of the hydrophilic MAA segment in the membrane was revealed by XPS analysis. Due to the pH-induced conformational transition of the PMAA chains, the permeability of the membranes cast from the grafted polymers displayed pronounced pH dependence, which was large under low pH values and small under high pH values.

Photografting of methacrylic acid onto hydroxyapatite particles surfaces

The unsaturated functional groups (CC) were introduced onto hydroxypatite (HAP) particles surfaces by esterification reaction between hydroxyl groups on the HAP surface and methacrylic acid (MAA). Then, graft polymerization of MAA onto the esterified HAP particles surfaces was carried out by ultraviolet light (UV) initiation. The structure of the surface-esterified and grafted HAP was studied by ESCA, FTIR, Scanning Electron microscopy, laser particle sizes analyze, esterification, and graft degrees tests. The results show that poly(methyl acrylic acid) (PMAA) is successfully inserted onto HAP particles surfaces by covalent bond linkage. The esterification degree between MAA and HAP particles increases with reaction temperature and time, and tends to level off at about 6 h under 90°C. The graft degree of MAA onto HAP particles with 1.14% esterification degree and its average particle sizes increase with UV initiation polymerization time, and to reach a maximum at 25 min under 40°C, then decrease as irradiation time further increases. The surfaces of the grafted HAP particles become rough and loose. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010