Amine-functionalized Surface Research Articles

Fluorescent silica nanoparticles with chemically reactive surface: Controlling spatial distribution in one-step synthesis

The encapsulation of fluorescent dyes inside silica nanoparticles is advantageous to improve their quality as probes. Inside the particle, the fluorophore is protected from the external conditions and its main emission parameters remains unchanged even in the presence of quenchers. On the other hand, the amine-functionalized nanoparticle surface enables a wide range of applications, as amino groups could be easily linked with different biomolecules for targeting purposes. This kind of nanoparticle is regularly synthesized by methods that employ templates, additional nanoparticle formation or multiple pathway process. However, a one-step synthesis will be an efficient approach in this sort of bifunctional hybrid nanoparticles.A co-condensation sol-gel synthesis of hybrid fluorescent silica nanoparticle where developed. The chemical and morphological characterization of the particles where investigated by DRIFTS, XPS, SEM and SAXS. The nanoparticle fluorescent properties were also assessed by excitation-emission matrices and time resolved experiments.We have developed a one-pot synthesis method that enables the simultaneous incorporation of functionalities, the fluorescent molecule and the amino group, by controlling co-condensation process. An exhaustive characterization allows the definition of the spatial distribution of the fluorescent probe, fluorescein isothiocyanate, inside the particle and reactive amino groups on the surface of the nanoparticle with diameter about 100nm.

Haptotatic Plasma Polymerized Surfaces for Rapid Tissue Regeneration and Wound Healing.

Skin has a remarkable capacity for regeneration; however, with an ever aging population, there is a growing burden to the healthcare system from chronic wounds. Novel therapies are required to address the problems associated with nonhealing chronic wounds. Novel wound dressings that can encourage increased reepithelialization could help to reduce the burden of chronic wounds. A suite of chemically defined surfaces have been produced using plasma polymerization, and the ability of these surfaces to support the growth of primary human skin cells has been assessed. Additionally, the ability of these surfaces to modulate cell migration and morphology has also been investigated. Keratinocytes and endothelial cells were extremely sensitive to surface chemistry showing increased viability and migration with an increased number of carboxylic acid functional groups. Fibroblasts proved to be more tolerant to changes in surface chemistry; however, these cells migrated fastest over amine-functionalized surfaces. The novel combination of comprehensive chemical characterization coupled with the focus on cell migration provides a unique insight into how a material's physicochemical properties affect cell migration.

Molecular Scale Description of Anion Competition on Amine-Functionalized Surfaces

Many industrial and biological processes involve the competitive adsorption of ions with different valencies and sizes at charged surfaces; heavy and precious metal ions are separated on the basis of their propensity to adsorb onto interfaces, often as anionic ion clusters (e.g., [MClx]n-). However, very little is known, both theoretically and experimentally, about the competition of factors that drive preferential adsorption, such as charge density or valence, at interfaces in technologically relevant systems. There are even contradictory pictures described by interfacial studies and real life applications, such as chlorometalate extractions, in which charge diffuse chlorometalate ions are extracted efficiently even though charge dense chloride ions present in the background are expected to occupy the interface. We studied the competition between divalent chlorometalate anions (PtCl62- and PdCl42-) and monovalent chloride anions on positively charged amine-functionalized surfaces using in situ specular X-ray reflectivity. Chloride anions were present in vast excess to simulate the conditions used in the commercial separation of heavy and precious metal ions. Our results suggest that divalent chlorometalate adsorption is a two-step process and that the divalent anions preferentially adsorb at the interface despite having a charge/volume ratio lower than that of chloride. These results provide fundamental insight into the structural mechanisms that underpin transport in phases that are relevant to heavy and precious metal ion separations, explaining the high efficiency of low charge density ion transport processes in the presence of charge dense anions.

One-step synthesis of amine-functionalized TiO2 surface for photocatalytic decolorization under visible light irradiation

Abstract One-step 3-aminopropyltriethoxysilane (APTES) modification surface of TiO 2 was successfully prepared for photocatalyts. The modified TiO 2 was characterized by means of techniques. As results, the monolayer and/or multilayer amino-silane coverage on TiO 2 surface substantially decreased the indirect band gap, leading to the formation of Si–N intermediate level within band gap and suppressing the electron–hole recombination. It subsequently enhanced the photoactivity. With increasing APTES contents, the c -value decreased whereas the formation of NH 2 and the oxygen chemisorption were apparently increased. However, the difference in APTES concentration significantly affected the hydrophobicity. The reduction in NH 3 + played an essential role in the retarding of photoactivity.

Amine-functionalized magnetic nanoparticles as robust support for immobilization of Lipase

Preparation of magnetic nanoparticles with controlled size and shape along with modulation of their surface properties via introduction of functional groups holds great prospect in the field of nanotechnology. Superparamagnetic, aqueous dispersible iron oxide nanoparticles (Fe3O4) with amine-functionalized surface were prepared through solvothermal method, using poly(ethylene imine) (PEI), ethanolamine (EA), and 2,2 ′-(ethylenedioxy)bis(ethylamine) (EDBE) as amine precursors. These aminated nanoparticles were used as support for the immobilization of lipase, an important industrial enzyme. Lipase was immobilized via glutaraldehyde coupling agent. These functionalized nanoparticles were characterized by XRD, FTIR, TEM, FESEM and VSM analysis. The maximum activity was obtained for the lipase immobilized on EDBE modified Fe3O4 nanoparticles. The lipase immobilized on EDBE-Fe3O4 depicted 83.9% relative activity with respect to the same amount of free lipase. Moreover, lipase immobilized on EDBE-Fe3O4 nanoparticles demonstrated good thermal and storage stability, and easy reusability. The kinetic parameters of lipase immobilized on EDBE-Fe3O4 were compared with those of free lipase and the apparent Michaelis-Menten constant of immobilized lipase was found to be nearly same as that of free lipase.

Controllable synthesis of amine-functionalized Fe3O4polyhedra for lipase immobilization

We developed an efficient strategy to synthesize Fe3O4 truncated cubes, rhombic dodecahedra and octahedra with exposed {100}/{110}, {110} and {111} facets, respectively. Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) spectra indicated that the Fe3O4 polyhedra were functionalized with a –NH2 group. Magnetic measurements revealed that the prepared products have a high saturation magnetization and low coercive force. Because of the magnetic nature and amine-functionalized surfaces, the as-synthesized Fe3O4 polyhedra were employed as ideal magnetic carriers for lipase immobilization. Bradford protein assays indicated that the lipase loading amounts on Fe3O4 truncated cubes, rhombic dodecahedra and octahedra were 174.7, 175.6 and 175.8 mg of protein per g, respectively. Thermal stability tests revealed that the lipase immobilized on Fe3O4 octahedra was bound with great efficiency preserving the high catalytic activity and amplifying the stability. Reusability assays indicated that the lipase immobilized on Fe3O4 octahedra can be reused 4 times without a marked loss of catalytic activity (<8%). This work demonstrated that the prepared Fe3O4 octahedra were more stable and had promising applications in biological fields.

Silanol-Assisted Carbinolamine Formation in an Amine-Functionalized Mesoporous Silica Surface: Theoretical Investigation by Fragmentation Methods.

The aldol reaction catalyzed by an amine-substituted mesoporous silica nanoparticle (amine-MSN) surface was investigated using a large molecular cluster model (Si392O958C6NH361) combined with the surface integrated molecular orbital/molecular mechanics (SIMOMM) and fragment molecular orbital (FMO) methods. Three distinct pathways for the carbinolamine formation, the first step of the amine-catalyzed aldol reaction, are proposed and investigated in order to elucidate the role of the silanol environment on the catalytic capability of the amine-MSN material. The computational study reveals that the most likely mechanism involves the silanol groups actively participating in the reaction, forming and breaking covalent bonds in the carbinolamine step. Therefore, the active participation of MSN silanol groups in the reaction mechanism leads to a significant reduction in the overall energy barrier for the carbinolamine formation. In addition, a comparison between the findings using a minimal cluster model and the Si392O958C6NH361 cluster suggests that the use of larger models is important when heterogeneous catalysis problems are the target.

Influence of Protein Surface Coverage on Anomalously Strong Adsorption Sites.

Serum albumin is commonly used as a blocking agent to reduce nonspecific protein adsorption in bioassays and biodevices; however, the details of this process remain poorly understood. Using single molecule techniques, we investigated the dynamics of human serum albumin (HSA) on four model surfaces as a function of protein concentration. By constructing super-resolution maps, identifying anomalously strong adsorption sites, and quantifying surface heterogeneity, we found that the concentration required for site blocking varied dramatically with surface chemistry. When expressed in terms of protein surface coverage, however, a more consistent picture emerged, where a significant fraction of strong sites were passivated at a fractional coverage of 10(-4). On fused silica (FS), "non-fouling" oligo (ethylene glycol) functionalized FS, and hydrophobically modified FS, a modest additional site blocking effect continued at higher coverage. However, on amine-functionalized surfaces, the surface heterogeneity exhibited a minimum at a coverage of ∼10(-4). Using intermolecular Förster resonance energy transfer (FRET), we determined that new anomalous strong sites were created at higher coverage on amine surfaces and that adsorption to these sites was associated with protein-protein interactions, i.e., surface-induced aggregation.

Evaluation of surface properties and pore structure of carbon on the activity of supported Ru catalysts in the aqueous-phase aerobic oxidation of HMF to FDCA

Different oxygen- and nitrogen-containing carbons were studied as supports of ruthenium catalysts for the alkaline aqueous-phase oxidation of 5-hydroxymethylfurfural (HMF) to the corresponding diacid 2,5-furandicarboxylic acid FDCA. The surface properties of catalyst support (active carbon or mesoporous carbon replicated from mesostructured silica) were suggested to be a key factor deeply influencing the oxidation rates of the different steps of this reaction of ruthenium nanoparticles. The results highlight that the HMF oxidation reaction in water does not well tolerate O-functional groups, which strongly adsorb water and then block access of the substrate to the active metal sites and decrease the reaction rates. N-containing carbons were anticipated to be beneficial for the acceleration of the first step of ruthenium-alcoholate species formation. The result was the opposite, with a detrimental effect on the reaction rate when the Ru precursor was reacted with the amine-functionalized surface.

Non-silicon substrate bonding mediated by poly(dimethylsiloxane) interfacial coating

In this paper, we introduce a simple and robust strategy for bonding poly(dimethylsiloxane) (PDMS) with various thermoplastic substrates to fabricate a thermoplastic-based closed microfluidic device and examine the feasibility of using the proposed method for realizing plastic–plastic bonding. The proposed bonding strategy was realized by first coating amine functionality on an oxidized thermoplastic surface. Next, the amine-functionalized surface was reacted with a monolayer of low-molecular-weight PDMS, terminated with epoxy functionality, by forming a robust amine-epoxy bond. Both the PDMS-coated thermoplastic and PDMS were then oxidized and permanently assembled at 25°C under a pressure of 0.1MPa for 15min, resulting in PDMS-like surfaces on all four inner walls of the microchannel. Surface characterizations were conducted, including water contact angle measurement, X-ray photoelectron spectroscopy (XPS), and fluorescence measurement, to confirm the successful coating of the thin PDMS layer on the plastic surface, and the bond strength was analyzed by conducting a peel test, burst test, and leakage test. Using the proposed method, we could successfully bond various thermoplastics such as poly(methylmethacrylate) (PMMA), polycarbonate (PC), polystyrene (PS), and poly(ethylene terephthalate) (PET) with PDMS without the collapse or deformation of the microchannel, and the proposed method was successfully extended to the bonding of two thermoplastics, PMMA, and PC.

Effect of octa(aminophenyl) polyhedral oligomeric silsesquioxane functionalized graphene oxide on the mechanical and dielectric properties of polyimide composites.

An effective method is proposed to prepare octa(aminophenyl) silsesquioxane (OAPS) functionalized graphene oxide (GO) reinforced polyimide (PI) composites with a low dielectric constant and ultrastrong mechanical properties. The amine-functionalized surface of OAPS-GO is a versatile starting platform for in situ polymerization, which promotes the uniform dispersion of OAPS-GO in the PI matrix. Compared with GO/PI composites, the strong interfacial interaction between OAPS-GO and the PI matrix through covalent bonds facilitates a load transfer from the PI matrix to the OAPS-GO. The OAPS-GO/PI composite film with 3.0 wt % OAPS-GO exhibited an 11.2-fold increase in tensile strength, and a 10.4-fold enhancement in tensile modulus compared with neat PI. The dielectric constant (D(k)) decreased with the increasing content of 2D porous OAPS-GO, and a D(k) value of 1.9 was achieved.

Chemical Modification of Semiconductor Interfaces for Mechanically Robust Solar Fuel Generating Devices

Introduction The increasing demand for lightweight, low cost, and mechanically robust solar-to-fuel electrochemical energy conversion devices motivates development of integrated semiconductor-polymer systems. [1, 2] One promising design for flexible photovoltaic [3, 4] or solar fuel generating [5, 6] devices employs arrays of Si microwires embedded in a polymer matrix that serves as a mechanical support, an electronic contact, and/or an ion conducting and fuel-separating membrane. Chemical and mechanical stability of the Si-polymer interface is critical for maintaining high junction quality and electronic/mechanical contact during sustained device operation. However, quantitative performance metrics and design methodologies for tailoring robust interfaces are needed. Previously, we demonstrated that single-wire in-situ mechanical pull-out tests can be used to measure interfacial shear strength between Si microwires with systematically varied surface functionalities and a polydimethylsiloxane (PDMS) matrix. The interfacial shear stress was found to correlate with the chemical bond strength resulting from covalent (-H, mixed –CH3/butenyl) or van der Waals (-CH3, octadecyl) bonds with PDMS. This revealed that macroscopic mechanical properties of the Si/polymer composite can be tailored by tuning Si surface chemistry. Results and Discussion Si microwire arrays (Fig. 1a) were functionalized with electrostatically charged end groups (-COO- and NH3 +) to target directed bonding with ionic sites in conducting polymers such as Nafion, which have relevance as membranes in solar water-splitting devices. Negatively-charged surfaces were introduced via functionalization with decanoic acid (CH3(CH2)8COOH, Fig. 1b) by a UV-initiated hydrosilylation reaction on a Si-H terminated surface in 10% decanoic / 90% toluene. FTIR spectroscopy on a planar Si(111) wafer indicated the disappearance of Si-H stretches after hydrosilyation and the appearance of characteristic C-H, C=O and C-O-H vibrational modes (Fig. 2a) indicative of successful attachment of surface groups in the desired orientation with –COOH ends exposed, as further confirmed by XPS in the C 1s region (Fig. 2b). Amine-functionalized Si microwire surfaces were also developed to introduce positive charges onto Si surfaces when protonated in acid. Functionalized microwire arrays were embedded into a Nafion membrane by spin casting of a Nafion-DMF solution. Wire-polymer arrays were then removed from the substrate and mounted on an SEM stub for nanomechanical testing. Specimens for single-wire pull-out tests were prepared using a focused ion beam (FIB) to carve a “dog-bone” shape into the tops of wires (Fig. 1a inset), and were then manipulated by a diamond grip attached to a nanomechanical testing arm within an in-situ SEM setup (Fig. 1c-d). Wire pull-out (tensile) tests were used to measure the maximum interfacial shear strength at the Si microwire-polymer interface prior to debonding of the wire and release from the matrix, and the strength of electrostatic (attractive and repulsive) interactions assembled under a range of pH conditions was measured. Si-H and Si-CH3 surface interaction strengths with Nafion were also studied and compared with prior results in PDMS. We also discuss the role of these molecular surfaces as junctions in electrochemical devices, including their surface chemical and electrochemical stability during operation.

Nanostructure synthesis at the solid-water interface: spontaneous assembly and chemical transformations of tellurium nanorods.

Bottom-up synthesis offers novel routes to obtain nanostructures for nanotechnology applications. Most self-assembly processes are carried out in three dimensions (i.e. solutions); however, the large majority of nanostructure-based devices function in two dimensions (i.e. on surfaces). Accordingly, an essential and often cumbersome step in bottom-up applications involves harvesting and transferring the synthesized nanostructures from the solution onto target surfaces. We demonstrate a simple strategy for the synthesis and chemical transformation of tellurium nanorods, which is carried out directly at the solid-solution interface. The technique involves binding the nanorod precursors onto amine-functionalized surfaces, followed by in situ crystallization/oxidation. We show that the surface-anchored tellurium nanorods can be further transformed in situ into Ag2Te, Cu2Te, and SERS-active Au-Te nanorods. This new approach offers a way to construct functional nanostructures directly on surfaces.

Amine-functionalized nanosilica-supported Dawson heteropolyacid: an eco-friendly and reusable photocatalyst for photodegradation of malachite green

Dawson heteropolyacid, H6[P2W18O62], was chemically anchored to the amine-functionalized nanosilica surface in different loadings. The synthesized nanocomposite was characterized by FT-IR spectroscopy and N2 adsorption experiments. The preservation of the structure of the Dawson and dispersion of the cluster on the support were verified on the basis of the spectroscopic data. The photocatalytic degradation efficiency of the synthesized nanocomposites was studied using an aqueous solution of malachite green dye as a model water pollutant. The mineralization of dye contents was investigated in different loadings from 10 to 30 % at room temperature. Decolorization was observed in shorter time using 30 % loading. The photocatalyst was reusable after the filtration and remained active even after being washed with hot water, which confirm its attachment firmly to the surface of amine-functionalized nanosilica.

Nano islet formation of formyl- and carboxyferrocene, -ruthenocene, -osmocene and cobaltocenium on amine-functionalized silicon wafers highlighted by crystallographic, AFM and XPS studies

Surface-hydroxylated silicon wafers, 8, were reacted with 3-aminopropyltrimethoxysilane, 9, to create wafers with amine-functionalized surfaces, 10. The metallocenylaldehydes FcCHO, 1 (Fc = ferrocenyl = FeII(C5H5)(C5H4)), RcCHO, 2 (Rc = ruthenocenyl = RuII(C5H5)(C5H4)), and OcCHO, 3 (Oc = osmocenyl = OsII(C5H5)(C5H4)) as well as the carboxylic acids FcCOOH, 4, RcCOOH, 5, OcCOOH, 6, and Cc+COOH·PF6−, 7 (Cc+ = cationic cobaltocenium = [CoIII(C5H5)(C5H4)]+), were reacted with 10 to covalently anchor the metallocenes on the wafers either via an imine (–CHN–) or amide (–NHCO–) bond. The aldehydes were anchored more effectively than the carboxylic acids. Binding energies of all important atoms in all seven systems were determined by XPS measurements. Metal binding energies of the amide-bonded metallocenes were consistently larger (up to 0.6 eV) than those of the imine-anchored systems. AFM and SEM measurements showed that the covalently anchored metallocenes aggregate into nano-islets of diameter between 40 and 100 nm depending on the metallocene and type of anchoring bond. Up to seven additional layers of unreacted metallocenylaldehyde or -acid further stacked on top of the main layer of metallocene to form each islet. These additional layers of metallocene of each islet are stabilized by a large network of secondary and/or tertiary bonding forces. The main film surfaces have average thicknesses ranging between 2 and 6 nm, while film roughness, which is mostly associated with the islets, was with one exception (that of the Oc–CONH– surface 14) between 17% and 68% of the film thickness. The crystal structures for OcCHO, 3, and Cc+COOH·PF6−, 7, was determined and the observed tertiary and secondary intermolecular interactions between independent molecules explains the formation of the nano-islets of each metallocene when anchored onto the aminated silicon wafers.

Silver–PEGylated dendrimer nanocomposite coating for anti-fouling thin film composite membranes for water treatment

This study proposes a facile method to fabricate thin film composite (TFC) membranes with silver–polyethylene glycol PEGylated dendrimer nanocomposite coatings on the surface to reduce both bacteria and protein fouling in the sustainable water treatment processes. Interestingly, the surfaces of TFC membranes have been imparted with different functionalities such as carboxylic acid, amine, PEG or silver nanoparticles in the modification process, which provide useful platforms to compare the anti-fouling properties of the four kinds of functional groups. Significant improvements on hydrophilicity have been found after modifications. All modified membranes show reduced attachment of E. coli and bovin serum albumin (BSA). Among them, the silver–PEGylated dendrimer nanocomposite membrane is subjected to the least fouling by the maximum fouling reduction of 99.8%. In particular, as a unique strength of this study, AFM force measurements were performed on membrane surfaces to study the interactions between protein and different surfaces. The adhesion force between the amine-functionalized surface and the tip suggests that the electrostatic interactions between the amine-modified membrane is very strong, resulting in a fast initial deposition of proteins on the membrane surface. The adhesion forces for PEG and silver nanoparticle modified membranes are small, which well explain the lower protein fouling of the membranes.

Modification of Surfaces by Chemical Transfer Printing Using Chemically Patterned Stamps

The preparation of well-defined molecular monolayers and their patterning on the microscale and nanoscale are key aspects of surface science and chemical nanotechnology. In this article, we describe the modification of amine-functionalized surfaces using a new type of contact printing based on chemically patterned, flat PDMS stamps. The stamps have discrete areas with surface-bond tetrafluorophenol (TFP) groups, which allow the attachment of carboxylic acids in the presence of coupling agents such as diisopropylcarbodiimide (DIC). The generated active esters can be reacted by placing the stamps in contact with amine-functionalized surfaces. The process leads to the transfer of acyl residues from the stamp to the substrate and therefore to a covalent attachment. Patterning occurs because of the fact that reaction and transfer take place only in areas with TFP groups present on the stamp surface. Different types of amine-decorated surfaces were successfully modified, and the transfer was visualized by fluorescence microscopy. To the best of our knowledge, the covalent transfer printing (CTP) of an immobilized molecular monolayer from one surface to another surface is unprecedented.

Immobilized silver nanoparticles enhance contact killing and show highest efficacy: elucidation of the mechanism of bactericidal action of silver

Antimicrobial materials with immobilized/entrapped silver nanoparticles (AgNPs) are of considerable interest. There is significant debate on the mode of bactericidal action of AgNPs, and both contact killing and/or ion mediated killing have been proposed. In this study, AgNPs were immobilized on an amine-functionalized silica surface and their bactericidal activity was studied concurrently with the silver release profile over time. This was compared with similar studies performed using colloidal AgNPs and AgCl surfaces that released Ag ions. We conclude that contact killing is the predominant bactericidal mechanism and surface immobilized nanoparticles show greater efficacy than colloidal AgNPs, as well as a higher concentration of silver ions in solution. In addition, the AgNP immobilized substrate was used multiple times with good efficacy, indicating this immobilization protocol is effective for retaining AgNPs while maintaining their disinfection potential. The antibacterial surface was found to be extremely stable in aqueous medium and no significant leaching (∼1.15% of total silver deposited) of the AgNPs was observed. Thus, immobilization of AgNPs on a surface may promote reuse, reduce environmental risks associated with leaching of AgNPs and enhance cost effectiveness.

Uniform epitaxial growth of Pt on Fe3O4 nanoparticles; synergetic enhancement to Pt activity for the oxygen reduction reaction

A synthetic strategy for achieving uniform shell-like epitaxial growth of Pt on Fe3O4 nanoparticles is introduced. The method involves the controlled high-density loading of Pt2+ by the linear growth of repeatedly stacked units of [Pt(NH2OH)4]2+ and [PtCl4]2−, followed by a subsequent reduction step. In comparison to commercial Pt-based fuel cell catalysts, the resulting Pt–Fe3O4 hybrid nanostructures were found to exhibit improved Pt specific activity for the electroreduction of oxygen in alkaline media, which is attributed to charge transfer from Fe3O4 to Pt. The Pt shell-type structure of the Pt–Fe3O4 hybrids was found to protect the Fe3O4 cores from corrosion, thus ensuring catalyst stability. A uniform Pt coating was also deposited evenly over SiO2 microspheres using this method, thus demonstrating its potential as a general strategy for platinum deposition on essentially any amine-functionalized surface.

표면 기능화된 실리카에 담지된 Al 유기금속화합물을 이용한 L-lactide 벌크중합 특성 연구

본 연구에서는 높은 분자량의 polylactide(PLA)를 중합하기 위하여 aluminum isopropyl oxide(<TEX>$Al(O-i-Pr)_3$</TEX>)를 아민기로 표면 기능화된 실리카에 담지하고 이를 촉매로 이용하여 생성된 PLA의 중합특성을 확인하였다. 담지촉매는 먼저 실리카 표면을 아민기를 갖는 실란화합물로 기능화한 후 <TEX>$Al(O-i-Pr)_3$</TEX>을 in-situ 합성하였다. 기능기에 담지된 <TEX>$Al(O-i-Pr)_3$</TEX>는 MAO(methyl aluminoxane) 존재하에 중합활성을 보였다. <TEX>$115^{\circ}C$</TEX>에서는 표면 기능화된 아민기양이 증가할수록 전환율과 분자량이 증가하였고, <TEX>$130^{\circ}C$</TEX>에서는 표면 기능화된 아민기양이 증가할수록 전환율은 감소하였으나 분자량은 크게 증가하여 표면 기능화된 아민기양이 3.0 mmol일 경우 44000 g/mol로 가장 높은 분자량을 얻었다. GPC curve를 통해 <TEX>$115^{\circ}C$</TEX> 중합온도에서는 분자량 분포곡선이 bimodal 형태에서 저분자량 부분이 크게 증가하여 shoulder 형태로 변화하였으며 <TEX>$130^{\circ}C$</TEX>에서는 GPC 단일피크를 보였다. 균일계 <TEX>$Al(O-i-Pr)_3$</TEX> 촉매보다 아민기로 표면 기능화된 실리카에 담지된 <TEX>$Al(O-i-Pr)_3$</TEX> 촉매가 더 높은 활성과 고분자량의 PLA를 합성할 수 있었다. In this study aluminum isopropyl oxide (<TEX>$Al(O-i-Pr)_3$</TEX>) was supported on the amine-functionalized surface of silica to synthesize high molecular weight (MW) polylactide (PLA), and it was tested for PLA polymerization behaviors. A silica was funtionalized with silane compound having amine groups, then in-situ treated with <TEX>$Al(O-i-Pr)_3$</TEX>. <TEX>$Al(O-i-Pr)_3$</TEX> attached to amine group on silica showed activity only in the presence of MAO (methyl aluminoxane). At the polymerization temperature of <TEX>$115^{\circ}C$</TEX>, the conversion and the MW of PLA were increased as the amount of silane was increased. At the polymerization temperature of <TEX>$130^{\circ}C$</TEX>, the conversion was decreased while the MW was increased drastically and reached to MW 44000 g/mol when the amine concentration was 3.0 mmol/g. A bimodal type GPC curve was shown at the polymerization temperature of <TEX>$115^{\circ}C$</TEX>. As the amount of amine group increased, the peaks of GPC curve were merged. At the polymerization of <TEX>$130^{\circ}C$</TEX>, a unimodal GPC curve was shown. <TEX>$Al(O-i-Pr)_3$</TEX> supported on amine-functionalized silica was able to produce higher MW PLA with enhanced activity compared to homogeneous <TEX>$Al(O-i-Pr)_3$</TEX>.