α‐Amino acids as initiators of ε‐caprolactone and L,L‐lactide polymerization

Biodegradable polymers/oligomers were successfully synthesized through a ring‐opening polymerization of ε‐caprolactone and L ,L ‐lactide, initiated by L ‐arginine and L ‐citrulline. The α‐amino acid initiators are natural, operationally simple, inexpensive, environmentally friendly and safe for human health. The polymerizations were performed with no solvents and without introducing any metal impurities. The chemical structures of the polymers obtained were elucidated using ¹H NMR, ¹³C NMR and Fourier transform infrared spectroscopies. In addition, incorporation of α‐amino acid molecules into the polymer chain was confirmed using matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry. Due to the significant biological activity of L ‐arginine and L ‐citrulline, these α‐amino acid initiators may open a new route for the synthesis of functional polymers especially for pharmaceutical applications. Copyright © 2011 Society of Chemical Industry     

Synthesis,characterization, and degradation of a novel L‐tyrosine‐derived polycarbonate for potential biomaterial applications

A novel class of pseudo‐poly(amino acid)s was synthesized with a cyclic dipeptide as new diphenole. Nonpeptide bonds alternating with a peptide bond structure were introduced into the backbone of the pseudo‐poly(amino acid)s. The cyclic dipeptide in this study was obtained from natural L ‐tyrosine. L ‐Tyrosine is a major nutrient amino acid with a phenolic hydroxyl group, so a polycarbonate derived from the cyclic dipeptide should possess more optimum mechanical properties, bioactivity, and biocompatibility. The hydrolytic specimen of the resulting polycarbonate was prepared by a modified solvent evaporation process. Under strongly alkaline conditions, degradation testing was performed. The tyrosine‐derived polycarbonate possessed a low glass‐transition temperature value and a high thermal decomposition temperature value, which formed a broad mean thermal processing range. The most important results of our study were the effects of the polycarbonate degradation on the local pH values, which were smaller than those of other biodegradable polymers [e.g., poly(lactic acid), poly(glycolic acid), and poly(lactic glycolic acid)]. The synthesized polymer and cyclic dipeptide were characterized with Fourier transform infrared, ¹³C‐NMR, and ¹H‐NMR spectroscopy to determine their chemical structures; by differential scanning calorimetry and thermogravimetric analysis to determine the thermal properties of the polymer; by gel permeation chromatography to determine the polymer's molecular weight; and by X‐ray diffraction to determine the polymer's morphology. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of ABA type tri‐block copolymers derived from p‐dioxanone,L‐lactide and poly(ethylene glycol)

A series of triblock co‐polymers, consisting of a poly(ethylene glycol) (PEG) central block joined to two blocks of random p‐dioxanone‐co‐L ‐lactide copolymers were synthesized by ring‐opening polymerization of p‐dioxanone (PDO) and L ‐lactide (LLA) initiated by PEG in the presence of stannous 2‐ethylhexanoate catalyst. The resulting copolymers were characterized by various techniques including ¹H and ¹³C NMR and FTIR spectroscopies, gel permeation chromatography, inherent viscosity, wide‐angle X‐ray diffractometry (WAXD) and differential scanning calorimetry (DSC). The conversion of PDO and L ‐lactide into the polymer was studied various mole ratios and at different polymerization temperature from ¹H NMR spectra. Results of WAXD and DSC showed that the crystallinity of PEG macroinitiator was greatly influenced by the composition of PDO and L ‐lactide in the copolymer. The triblock copolymers with low molecular weight were soluble in water at below room temperature. © 2003 Society of Chemical Industry     

Solvent‐ and thermal‐induced crystallization of poly‐L‐lactic acid in supercritical CO2 medium

The effect of different annealing treatments with supercritical carbon dioxide (SCCO₂) on the structural and mechanical properties of semicrystalline poly‐L ‐lactic acid (L ‐PLA) was investigated. 2000, 27,000, 100,000, and 350,000 g mol^?1 molecular weight L ‐PLA polymers were used in the study. The solid‐state processing of L ‐PLA at temperatures lower than the effective melting point led to solvent‐ and thermal‐induced crystallization. Solvent‐induced and isothermal crystallization mechanisms could be considered similar regarding the increase of polymer chain mobility and mass‐transfer in the amorphous region; however, quite different microstructures were obtained. SCCO₂ solvent‐induced crystallization led to polymers with high crystallinity and melting point. On the contrary, SCCO₂ thermal‐induced crystallization led to polymers with high crystallinity and low melting point. For these polymers, the hardness increased and the elasticity decreased. Finally, the effect of dissolving SCCO₂ in the molten polymer (cooling from the melt) was analyzed. Cooling from the melt led to polymers with high crystallinity, low melting point, low hardness, and low elasticity. Distinctive crystal growth and nucleation episodes were identified. This work also addressed the interaction of SCCO₂‐drug (triflusal) solution with semicrystalline L ‐PLA. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of polypeptide containing liver‐targeting group

Glycyrrhetinic acid, glycyrrhizic acid and bile acid were reported to be accumulated in liver. A series of novel liver‐specific targeting polypeptides, poly(γ‐benzyl‐L ‐glutamate), were synthesized by ring‐opening polymerization (ROP) of N‐carboxyanhydride of γ‐benzyl‐L ‐glutamate (BLG‐NCA) with amine‐terminated compounds containing the above‐mentioned liver‐targeting group as an initiator. The molecular weights of the polypeptides were measured by gel permeation chromatography. The structures of these polypeptides and their initiators were confirmed by FTIR and ¹H‐NMR spectroscopy. The results demonstrate that it is an efficient strategy to introduce a liver‐targeting group into polymers via amine‐terminated compounds containing glycyrrhetinic acid, glycyrrhizic acid and bile acid. The novel polymers have potential medical applications in targeted drug delivery. Copyright © 2006 Society of Chemical Industry     

Chiral separation of D,L‐tyrosine through nitrocellulose membrane

Enantioselective membrane was prepared using nitrocellulose as membrane material. The flux and permselective properties of membrane using water solution of D ,L ‐tyrosine as feed solution were studied. The top surface and cross‐section morphology of the resulting membrane were examined by scanning electron microscopy. The optical resolution of over 85% enantiomeric excess was achieved when the enantioselective membrane was prepared with 25 wt % nitrocellulose and 15 wt % N,N‐dimethylformamide in the casting solution of methanol, 10°C temperature of water bath for the gelation of the membrane, and the operating pressure and the feed concentration of the D ,L ‐tyrosine were 6 kgf/cm² and 0.25 mg/mL, respectively. Since the nitrocellulose contains a large amount of chirality active carbons on the backbone structure and is possible to form helical structure, it is considered to be the reason for the enantioselectivity of the membrane. This is the first report that nitrocellulose can be used as a membrane material. This work indicates that the large‐scale purification of chiral molecules from racemic mixtures will be realized by the enantioselective membrane technique in the near future and that the enantioselective nitrocellulose membrane could soon become very attractive for industrial uses. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Compositional analysis of biodegradable polyphosphoester copolymers using nmr spectroscopic methods

The chemical composition and quantitative molar ratios among all components of biodegradable polyphosphoester copolymers of DL ‐lactide and ethylphosphate were determined by a comprehensive set of NMR spectroscopic methods. The polyphosphoester copolymers studied were synthesized using condensation polymerization of oligomeric DL ‐lactide prepolymers and ethyl dichlorophosphate. Conclusive identification of the chemical shift patterns of all functional groups in the copolymers required additional NMR methods such as ³¹P‐NMR and two‐dimensional ¹H–¹H COSY NMR, in addition to the synthesis and comparative NMR analysis of model compounds possessing identical phosphoester linkages in the polyphosphoester copolymers. For the polymers synthesized using the bulk polycondensation process, ¹H–¹H COSY NMR analysis revealed the presence of a small amount of side products that were undetected by ¹H‐NMR alone. These side reactions most likely occurred between the pendant ethoxy group of the phosphoesters and the hydrogen chloride gas generated in the bulk polycondensation process. ³¹P‐NMR spectra of the copolymers revealed a consistent triple‐peak pattern characteristic of phosphoesters linked to a racemic mixture of D,L ‐lactides. These results offered new insight into the side reactions occurring in bulk polymerization of polyphosphoesters and provided a powerful tool of characterizing complex biodegradable polymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4021–4031, 2003     

Characterization and mechanical properties of water‐soluble poly(vinyl alcohol) grafted with lactic acid and glycolic acid

Poly(vinyl alcohol) (PVA), fully or partially hydrolyzed, was reacted with D,L ‐lactic acid and glycolic acid in different conditions to synthesize polymers with pendant lactate and glycolate groups. Various degrees of grafting were obtained. ¹H‐ and ¹³C‐NMR analysis as well as thermal and mechanical methods were used to characterize the polymers. Such grafts lead to polymers with lower glass transition temperature, therefor enhancing the polymers solubility in cold water (10°C) and improving flexibility and elasticity as well as tear resistance. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 142–147, 2001     

Hydrolytic degradation and crystallization behavior of linear 2‐armed and star‐shaped 4‐armed poly(l‐lactide)s: Effects of branching architecture and crystallinity

“Linear” aliphatic polyesters composed of two poly(l ‐lactide) arms attached to 1,3‐propanediol and “star‐shaped” ones composed of four poly(l ‐lactide) arms attached to pentaerythritol (2‐L and 4‐L polymers, respectively) with number‐average molecular weight (M_n) = 1.4–8.4 × 10⁴g/mol were hydrolytically degraded at 37°C and pH = 7.4. The effects of the branching architecture and crystallinity on the hydrolytic degradation and crystalline morphology change were investigated. The degradation mechanism of initially amorphous and crystallized 2‐L polymers changed from bulk degradation to surface degradation with decreasing initial M_n; in contrast, initially crystallized higher molecular weight 4‐L polymer degraded via bulk degradation, while the degradation mechanism of other 4‐L polymers could not be determined. The hydrolytic‐degradation rates monitored by molecular‐weight decreases decreased significantly with increasing branch architecture and/or higher number of hydroxyl groups per unit mass. The hydrolytic degradation rate determined from the molecular weight decrease was higher for initially crystallized samples than for initially amorphous samples; however, that of 2‐L polymers monitored by weight loss was larger for initially amorphous samples than for initially crystallized samples. Initially amorphous 2‐L polymers with an M_n below 3.5 × 10⁴g/mol crystallized during hydrolytic degradation. In contrast, the branching architecture disturbed crystallization of initially amorphous 4‐L polymers during hydrolytic degradation. All initially crystallized 2‐L and 4‐L polymers had δ‐form crystallites before hydrolytic degradation, which did not change during hydrolytic degradation. During hydrolytic degradation, the glass transition temperatures of initially amorphous and crystallized 2‐L and 4‐L polymers and the cold crystallization temperatures of initially amorphous 2‐L and 4‐L polymers showed similar changes to those reported for 1‐armed poly(l ‐lactide). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41983.     

Chemical composition and structural feature of Populus gansuensis hemicellulosic polymers

Hemicellulosic polymers A and B were isolated from Populus gansuensis by extracting the chlorite‐delignified residue with 10% KOH. Fractional precipitation of hemicellulose B by graded ethanol resulted in six subfractions varying in yield, molecular size distribution, and sugar composition. Macromolecular and more linear hemicellulosic polymers with higher yields were preferentially precipitated in relatively lower ethanol concentrations, while more branched and complex hemicellulosic polymers with lower molecular weights were obtained in relatively higher ethanol concentrations. Chemical and spectral evidence suggested that H30 subfraction obtained by 30% ethanol precipitation was assumed to be 4‐O‐methyl‐D ‐glucurono‐D ‐xylans, with 4‐O‐methyl‐D ‐glucuronic acid linked to C‐2 of (1→4)‐β‐D ‐xylan. On average for every six D ‐xylopyranosyl residues, there is one 4‐O‐methyl‐D ‐glucuronic acid group. Hemicellulosic subfraction H75 precipitated at the ethanol concentration of 75% was more branched, and presumed to be heterogeneous mixture of arabinoglucurnoxylan and galactoglucomannan. In addition, the thermal stability of the linear large molecular hemicellulosic subfraction H30 appeared higher than the branched subfraction H75. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of novel polyarylates bearing NLO moieties

A series of thermally stable second‐order nonlinear optical polyarylates containing azo side‐chain groups have been obtained by interfacial polycondensation. Theoretical calculations of the static hyperpolarizabilities, first‐ and second‐order hyperpolarizability, were carried out. The structures of the obtained monomers and polymers were confirmed by infrared, ¹H NMR and ultraviolet spectroscopies. Thermal and optical properties of the obtained polymers were evaluated. The investigations show that some of the new polymers obtained in this study may find use in optical applications. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2195–2201, 2006     

Strong resistance of poly (ethylene glycol) based L‐tyrosine polyurethanes to protein adsorption and cell adhesion

Biofouling that involves protein adsorption, cell and bacteria adhesion, and biofilm formation between a surface and biological entities is a great challenge for biomedical and industry applications. In this work, L ‐tyrosine‐derived polyurethanes (L ‐polyurethane) with different molecular weights of poly(ethylene glycol) (PEG) were synthesized, characterized and coated on gold surfaces using spin‐coating. The non‐fouling activity of different L ‐polyurethane films was evaluated by protein adsorption and cell adhesion. Surface plasmon resonance and cell assay results demonstrate that the PEG content in these L ‐polyurethanes contributes excellent resistance to protein adsorption and cell attachments. This work provides alternative and effective biomaterials for potential applications in blood‐contacting devices. Copyright © 2011 Society of Chemical Industry     

Synthesis and studies of blue light emitting polymers containing triphenylamine‐substituted fluorene and diphenylanthracene moiety

Photoluminescent (PL) polymers containing triphenylamine‐substituted fluorene and diphenylanthracene (DPA) units were synthesized by aromatic nucleophilic substitution reaction. The light emitting polymers (LEPs) contains hole‐transporting triphenylamine (TPA) groups at the C‐9 position of fluorene and DPA‐emitting segments in the main chain. The obtained polymers were soluble in various organic solvents and thermally stable. The synthesized polymers were successfully characterized by elemental analyses, FTIR and, ¹H NMR spectroscopy. The electrochemical measurements and optical properties of the polymers were also studied. The obtained polymers showed significant blue emission. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterization of readily soluble polyarylates derived from either 1,1‐bis(4‐hydroxyphenyl)‐1‐phenylethane or tetramethylbisphenol A and aromatic diacid chlorides

A series easily soluble polyarylates were synthesized from either 1,1‐bis(4‐hydroxyphenyl)‐1‐phenylethane or tetramethylbisphenol A with various aromatic diacid chlorides by the two‐phase interfacial polycondensation. These polyarylates have the inherent viscositiesin the range of 0.36–0.97 dL/g, and their number‐average and weight‐average molecular weights determined by gel permeation chromatography are 14,200–43,200 and 31,900–102,500, respectively. All these polyarylates are readily soluble in a wide range of organic solvents, thus these polymers can be convenient to process into heat resistance films by cast, spin‐ or dip‐coating. The polyarylates have the glass transition temperatures in the range of 165.0–201.6°C. The pendent phenyl‐containing polyarylates reveal excellent thermal stability, and their initial degradation temperatures are all above 480°C and char yields at 700°C are 37.97–40.53% in nitrogen atmosphere. However, the polymers prepared from tetramethylbisphenol A have a large decrease in thermal stability, and their initial degradation temperatures in nitrogen are only about 440°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

High molecular weight poly (L‐lactic acid) clay nanocomposites via solid‐state polymerization

We propose here, a novel technique to synthesize high molecular weight (MW) poly (L ‐lactic acid)‐clay nanocomposite (PLACN), via solid state polymerization (SSP). We synthesize prepolymer of PLACN (pre‐PLACN) from both, L ‐lactic acid and L ‐lactide, as starting materials. Synthesis of pre‐PLACN from L ‐lactic acid is carried out via in situ melt polycondensation (MP) of L ‐lactic acid oligomer, followed by SSP, to achieve high MW PLACN (M_w ∼ 138,000 Da). In case of L ‐lactide as the starting material, we prepare L ‐lactide–clay intercalated mixture which yields moderate MW pre‐PLACN during subsequent ring opening polymerization (ROP). Interestingly, ROP is performed by using hydroxyl functionalized ternary catalyst system (L ‐lactide–Sn(II) octoate–oligo (L‐lactic acid) complex), which provides the terminal hydroxyl end‐groups, required for step‐growth SSP. Pre‐PLACN MW is now increased to M_w ∼ 127,000 Da, by the subsequent SSP process. ¹H NMR analyses confirm that these end‐groups, are indeed consumed during SSP. During SSP, the PLACN also achieves up to 90% crystallinity, which may be due to the synchronization of the slow step‐growth SSP of poly(L ‐lactic acid) (PLA) with the crystallization kinetics. Optical purity of PLACNs is similar to that of neat PLA, whereas the thermal stability of PLACNs is significantly superior. As evidenced by wide‐angle X‐ray scattering/small‐angle X‐ray scattering analyses and in line with the literature, both, intercalated and exfoliated PLACN morphologies, have been synthesized, by suitable selection of clays. We also verify the correlation between the PLA semicrystalline morphology and the PLACN morphology, which is consistent with those of PLACN synthesized by other techniques. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Influence of racemization on stereocomplex‐induced gelation of water‐soluble polylactide–poly(ethylene glycol) block copolymers

Ring‐opening polymerization of L ‐ or D ‐lactide was realized at 140 °C for a period of 7 days in the presence of dihydroxyl poly(ethylene glycol) (PEG), with M?_n = 4000 g mol^?1, using zinc lactate as initiator. The resulting poly(L ‐lactide)–PEG–poly(L ‐lactide) and poly(D ‐lactide)–PEG–poly(D ‐lactide) triblock copolymers are water soluble with polylactide (PLA) block length ranging from 11 to 17 units. Both the tube inverting method and rheological measurements were used to evaluate the gelation properties of aqueous solutions containing single copolymers or L /D copolymer pairs. Stereocomplexation between poly(L ‐lactide) and poly(D ‐lactide) blocks is observed for mixed solutions. Hydrogel formation is detected in the case of relatively long PLA blocks (DP _PLA = 17), but not for copolymers with shorter PLA blocks (DP _PLA = 11–13) due to partial racemization of L ‐lactyl units. Racemization is largely reduced when the reaction time is shortened to 1 day. Under these conditions, DP _PLA of 8 is sufficient for the stereocomplexation of PLA–PEG block copolymers, and DP _PLA above 10 leads to the formation of hydrogels of PLA–PEG block copolymers. On the other hand, racemization appears as a general phenomenon in the (co)polymerization of L ‐lactide with Zn(Lac)₂ as initiator, although it is negligible or undetectable in the case of high molar mass polymers. Therefore, racemization is the limiting factor for the stereocomplexation‐induced gelation of water‐soluble PLA–PEG block copolymers where the PLA block length generally ranges from 10 to 30. Reaction conditions including initiator, time and temperature should be strictly controlled to minimize racemization. Copyright © 2010 Society of Chemical Industry     

Synthesis and characterization of the biomaterial poly(lactic acid‐co‐Nε‐carbobenzoyloxy‐L‐lysine) via direct melt copolymerization

With D,L ‐lactic acid and N^ϵ‐carbobenzoyloxy‐L ‐lysine [Lys(Z)] as the starting monomer material and tin dichloride as the catalyst, the drug carrier material poly(lactic acid‐co‐N^ϵ‐carbobenzoyloxy‐L ‐lysine) was synthesized via direct melt polycondensation. The copolymer was systematically characterized with intrinsic viscosity testing, Fourier transform infrared spectroscopy, ¹H‐NMR, gel permeation chromatography, differential scanning calorimetry, and X‐ray diffraction. The influences of different feed molar ratios were examined. With increasing molar feed content of Lys(Z), the intrinsic viscosity, weight‐average molecular weight, and polydispersity index (weight‐average molecular weight/number‐average molecular weight) gradually decreased. Because of the introduction of Lys(Z) with a big aromatic ring into the copolymer, the glass‐transition temperature gradually increased with increasing feed charge of Lys(Z), and all of the copolymers were amorphous. The copolymers, with weight‐average molecular weights from 10,500 to 6900 Da, were obtained and could reach the molecular weight level of poly(lactic acid) modified by Lys(Z) via the ring‐opening polymerization of the cyclic intermediates, such as lactide and morpholine‐2,5‐dione. However, a few terminal carboxyl groups might have been deprotected during the polymerization reaction under high temperatures. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and structural characterization of novel chiral nanostructured poly(esterimide)s containing different natural amino acids and 4,4′‐thiobis(2‐tert‐butyl‐5‐methylphenol) linkages

Pyromellitic dianhydride (benzene‐1,2,4,5‐tetracarboxylic dianhydride) (1) was reacted with several amino acids in acetic acid and the resulting imide‐acid [N,N′‐(pyromellitoyl)‐bis‐L ‐amino acid diacid] (4a–4d) was obtained in high yield. The direct polycondensation reaction of these diacids with 4,4′‐thiobis(2‐tert‐butyl‐5‐methylphenol) (5) was carried out in a system of tosyl chloride(TsCl), pyridine, and N,N‐dimethyl formamide (DMF) to give a series of novel optically active poly(esterimide)s. Step‐growth polymerization was carried out by varying the time of heating and the molar ratio of TsCl/diacid, and the optimum conditions were achieved. These new chiral polymers were characterized with respect to chemical structure and purity by means of specific rotation experiments, FTIR, ¹H‐NMR, X‐ray diffraction, elemental, and thermogravimetric analysis (TGA) field emission scanning electron microscopy (FE‐SEM) techniques. These polymers are readily soluble in many polar organic solvents like DMF, N,N‐dimethyl acetamide, dimethyl sulfoxide, N‐methyl‐2‐pyrrolidone, and protic solvents such as sulfuric acid. TGA showed that the 10% weight loss temperature in a nitrogen atmosphere was more than 390°C; therefore, these new chiral polymers have useful levels of thermal stability associated with good solubility. Furthermore, study of the surface morphology of the obtained polymers by FE‐SEM showed that each polymers exhibit nanostructure morphology. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterization of star‐shaped poly(ethylene glycol)‐block‐poly(L‐lactic acid) copolymers by melt polycondensation

Compared with linear diblock or triblock poly(ethylene glycol)‐block‐poly(L ‐lactic acid) copolymer (PEG‐b‐PLLA), star‐shaped PEG‐b‐PLLA (sPEG‐b‐PLLA) copolymers exhibit smaller hydrodynamic radius and lower viscosity and are expected to display peculiar morphologies, thermal properties, and degradation profiles. Compared with the synthesis routine of PEG‐b‐PLLA form lactide and PEG, the traditional synthesis routine from LA and PEG were suffered by the low reaction efficiency, low purity, lower molecular weight, and wide molecular weight distribution. In this article, multiarm sPEG‐b‐PLLA copolymer was prepared from multiarm sPEG and L ‐lactic acid (LLA using an improved method of melt polycondensation, in which two types of sPEG, that is, sPEG₁ (four arm, Mn = 4300) and sPEG₂ (three arm, Mn = 3200) were chosen as the core. It was found the molecular weight of sPEG‐b‐PLLA could be strongly affected by the purity of LLA and sPEGs, and the purification technology of vacuum dewater and vacuum distillation could help to remove most of the impurities in commercial available LLA. The polymers, including sPEG and sPEG‐b‐PLLA with varied core (sPEG₁ and sPEG₂) and LLA/sPEG feeding ratios, were characterized and confirmed by ¹H‐NMR and ¹³C‐NMR spectroscopy, Fourier transform infrared spectroscopy (FT‐IR) and gel permeation chromatography, which showed that the terminal hydroxyl group in each arm of sPEGs had reacted with LLA to form sPEG‐b‐PLLA copolymers with fairly narrow molecular weight distribution. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Side chain functionality dominated the chromatography of N‐protected amino acid on molecularly imprinted polymer

Molecularly imprinted polymer (MIP) with N^α‐protected amino acid as the print molecule was prepared and used as the stationary phase for the chromatographic study of molecular recognition. Particles of MIP were prepared by photopolymerization of 4‐vinylpyridine in the presence of tert‐butyloxycarbonyl‐L ‐tyrosine (Boc‐L ‐Tyr) and packed into a column for the chromatographic resolution of Boc‐L ‐Tyr and tert‐butyloxycarbonyl‐L ‐phenylalanine (Boc‐L ‐Phe). These two N^α‐protected amino acids that differ from each other in the side chain with one hydroxyl group on the benzene ring could be well separated on the MIP. A separation factor of about two was achieved by using a mixture of acetonitrile (99.5 v/v %) and acetic acid (0.5 v/v %) as the mobile phase. Results suggest that the interaction between hydroxyl group in the side chain of amino acid and pyridine in the polymer dominated the selective adsorption of print molecule on the MIP. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007