Baroplastic behavior of miscible block copolymer blends

Pressure dependence of various phase transitions for the miscible block copolymer (BCP) blends was evaluated by depolarized light scattering (DPLS) and small-angle neutron scattering (SANS) measurements, in which the blends consist of a polystyrene-b-poly(n-butyl methacrylate) (PS-b-PnBMA) and a deuterated polystyrene-b-poly(n-hexyl methacrylate) (dPS-b-PnHMA). Excellent baroplasticity was observed in nearly symmetric blends of PS-b-PnBMA/dPS-b-PnHMA, leading to the most outstanding pressure coefficients, |dT/dP|, in a closed-loop type phase behavior between a lower disorder-to-order transition (LDOT) and an order-to-disorder transition (ODT) type phase behavior. Together with the estimated pressure coefficients based on the values of enthalpic and volumetric changes at phase transitions, we demonstrate that the entropic compressibility for the miscible BCP blends is a baroplastic indicator, which was characterized by the negative volume change on mixing (ΔV_mix) at transitions.     

Synthesis and characterization of fluorene end-labeled polymers prepared by nitroxide-mediated polymerization

The fluorene-based alkoxyamine 9-(2,2,6,6-tetramethyl-4-hydroxypiperidinyloxy)fluorene was prepared and investigated as a unimolecular initiator in the nitroxide-mediated polymerization (NMP) of styrene. Reactions performed in either bulk or ethereal solvents at 125 °C generated polymers possessing low polydispersity indices (PDIs) and number average molecular weight (M_n) values close to those anticipated based on monomer-to-initiator ratios. A linear relationship between monomer conversion and M_n values was observed by analysis of reaction aliquots with ¹H NMR and gel permeation chromatography (GPC), while PDI values remained low throughout. Analysis of the polymers by UV–vis spectroscopy indicated that approximately 80% of the polymer chains were labeled with the fluorene chromophore, while fluorescence spectroscopy was used to verify that the fluorene was polymer-bound.     

One pot,two step sequence converting atom transfer radical polymerization directly to radical trap-assisted atom transfer radical coupling

Monobrominated polystyrene (PStBr) chains were prepared using standard atom transfer radical polymerization (ATRP) procedures at 80 °C in THF, with monomer conversions allowed to proceed to approximately 40%. At this time, additional copper catalyst, reducing agent, and ligand were added to the unpurified reaction mixture, and the reaction was allowed to proceed at 50 °C in an atom transfer radical coupling (ATRC) phase. During this phase, polymerization continued to occur as well as coupling; expected due to the substantial amount of residual monomer remaining. This was confirmed using gel permeation chromatography (GPC), which showed increases in molecular weight not matching a simple doubling of the PStBr formed during ATRP, and an increase in monomer conversion after the second phase. When the radical trap 2-methyl-2-nitrosopropane (MNP) was added to the ATRC phase, no further monomer conversion occurred and the resulting product showed a doubling of peak molecular weight (M_p), consistent with a radical trap-assisted ATRC (RTA-ATRC) reaction.     

The effect of polystyrene-block-poly(4-vinylpyridine) prepared by a RAFT method in the dispersion polymerization of MMA

The dispersion polymerization of methyl methacrylate (MMA) has been carried out using polystyrene-block-poly(4-vinylpyridine) copolymer [P(S-b-4VP)], which was prepared by a reversible addition-fragmentation chain transfer (RAFT) method, as a steric stabilizer in an alcohol media. The stable polymer particles were obtained when the block copolymer concentrations increased from 1 to 10 wt% relative to the monomer and the average particle sizes decreased from 5.3 to 3.4 μm with the increasing concentration of the block copolymer. In particular, the incorporation of 2 wt% polystyrene-block-poly(4-vinylpyridine) produced 4.3 μm of monodisperse PMMA particles with 2.14% of C_v. Thus, the P(S-b-4VP) block copolymer prepared by the RAFT method is working not only as a steric stabilizer, but also in providing monodisperse micron-sized PMMA particles.     

Synthesis of novel block copolymers containing polyhedral oligomeric silsesquioxane (POSS) pendent groups via ring-opening metathesis polymerization (ROMP)

Ring-opening metathesis copolymerization of norbornene ethyl polyhedral oligomeric silsesquioxane monomer (NBEPOSS) and 2-endo-3-exo-5-norbornene-2,3-dicaboxylic acid trimethyl ester (NBETMS) was performed using a Ru-based catalyst, RuCl₂(CHPh)(PCy₃)₂. The block copolymers poly(NBETMS-b-NBEPOSS) were then converted to poly(NBECOOH-b-NBEPOSS) by hydrolysis and precipitation. The polymers were characterized by NMR and GPC and the actual NBEPOSS contents were found in good correspondence with the theoretical values. A linear dependence of M_n on conversion and a linear dependence of ln([M₀]/[M]) on reaction time observed in the polymerization of NBETMS suggest that chain breaking reactions such as termination and chain transfer are minimal. Low PDI values and smooth GPC peak shifts during polymerization after addition of a second batch of the same monomer or a NBEPOSS monomer also reflect a living process.     

Allyl functionalized telechelic linear polymer and star polymer via RAFT polymerization

Reversible addition-fragmentation chain transfer (RAFT) polymerization of styrene using bisallyl trithiocarbonate as a chain transfer agent (CTA) was studied. The polymerization exhibited first-order kinetics and the molecular weight increased linearly with increase of monomer conversion. Well defined allyl-functionalized telechelic polystyrene (PS), poly(tert-butyl acrylate) (PtBA) and corresponding triblock copolymers, polystyrene-b-poly(n-butyl acrylate)-b-polystyrene (PS-b-PnBA-b-PS) and poly(tert-butyl acrylate)-b-polystyrene-b-poly(tert-butyl acrylate) (PtBA-b-PS-b-PtBA) were prepared as characterized with GPC and NMR analysis. The allyl-end groups of the telechelic PS have been switched to 1,2-dibromopropyl groups quantitatively by bromine addition reaction, further substitution of the bromide with azide was also made. Furthermore, star PS with allyl-end-functionalized arms was synthesized by RAFT polymerization of divinyl benzene using allyl-functionalized PS as a macro-CTA via arm-first approach. Star polymer with a thiol-functionalized core was generated by aminolysis reaction of the star polymer and ethylenediamine. As a result, difunctionalized star polymer with allyl and thiol groups was obtained and was used as a stabilizer for the formation of gold nanoparticles.     

Synthesis of linear tetrablock quaterpolymers via atom transfer radical polymerization and a click coupling approach

We report the synthesis of a well-defined linear tetrablock quaterpolymer of poly(butyl acrylate)-b-polystyrene-b-poly(methyl acrylate)-b-poly(methyl methacrylate) by combining atom transfer radical polymerization (ATRP) and a click coupling approach. For this purpose, polystyrene-b-poly(butyl acrylate) (AB) was prepared by ATRP using macroinitiator as α-trimethylsilyl(TMS)-alkyne ω-bromo polystyrene. The α-(TMS) end of the AB diblock copolymer was deprotected using tetrabutylammonium fluoride (TBAF) in THF. The ω-azide end of the CD diblock copolymer was made from poly(methyl methacrylate)-b-poly(methyl acrylate) (CD) via transformation of the bromine chain end by a simple nucleophilic substitution reaction with NaN₃ in DMF. Click coupling between the ω-azide end in CD diblock copolymer with the α-alkyne end in the AB diblock copolymer was then performed by Cu¹-catalyzed (3+2) cycloaddition. Gel permeation chromatography (GPC), FT-IR and ¹H NMR spectroscopy confirmed the successful formation of a linear ABCD tetrablock copolymer via ATRP and click coupling.     

SG1-based alkoxyamine bearing a N-succinimidyl ester: A versatile tool for advanced polymer synthesis

This paper reports the preparation of a MAMA-SG1 (BlocBuilder™) derived alkoxyamine bearing a N-succinimidyl (NHS) ester group 1, valuable for functional and advanced polymer synthesis. This alkoxyamine was exploited following two strategies: (i) a post-functionalization approach based on the transformation of α-NHS chain ends of polymers previously obtained by nitroxide mediated polymerization (NMP) from 1 (path A) and (ii) a pre-functionalization approach based on the functionalization of alkoxyamine 1 prior to NMP (path B). Path A was demonstrated by derivatization of α-NHS functionalized polystyrenes with ethanolamine, yielding hydroxyl-functionalized polystyrenes. Path B was illustrated by two examples: first, a OH functional alkoxyamine initiator, prepared by reaction of 1 with ethanolamine, was used for the synthesis of polystyrene-b-poly(d,l-lactide) by combining NMP and ring-opening polymerization. Secondly, a poly(propylene oxide)-SG1 macroalkoxyamine, obtained from reaction of 1 with NH₂-functionalized poly(propylene oxide), was used as a macroinitiator for NMP of styrene to obtain a PS-b-PPO block copolymer.     

Synthesis and self-assembly behaviors of three-armed amphiphilic block copolymers via RAFT polymerization

The novel trifunctional reversible addition-fragmentation chain transfer (RAFT) agent, tris(1-phenylethyl) 1,3,5-triazine-2,4,6-triyl trithiocarbonate (TTA), was synthesized and used to prepare the three-armed polystyrene (PS₃) via RAFT polymerization of styrene (St) in bulk with thermal initiation. The polymerization kinetic plot was first order and the molecular weights of polymers increased with the monomer conversions with narrow molecular weight distributions (M_w/M_n ≤ 1.23). The number of arms of the star PS was analyzed by gel permeation chromatography (GPC), ultraviolet visible (UV-vis) and fluorescence spectra. Furthermore, poly(styrene-b-N-isopropylacrylamide)₃ (PS-b-PNIPAAM)₃, the three-armed amphiphilic thermosensitive block copolymer, with controlled molecular weight and well-defined structure was also successfully prepared via RAFT chain extension method using the three-armed PS obtained as the macro-RAFT agent and N-isopropylacrylamide as the second monomer. The copolymers obtained were characterized by GPC and ¹H nuclear magnetic resonance (NMR) spectra. The self-assembly behaviors of the three-armed amphiphilic block copolymers (PS-b-PNIPAAM)₃ in mixed solution (DMF/CH₃OH) were also investigated by high performance particle sizer (HPPS) and transmission electron microscopy (TEM). Interestingly, the lower critical solution temperature (LCST) of aqueous solutions of the three-armed amphiphilic block copolymers (PS-b-PNIPAAM)₃ decreased with the increase of relative length of PS in the block copolymers.     

Vesicle formation of polystyrene-block-poly (ethylene oxide) block copolymers induced by supercritical CO2 treatment

A novel route for a preparation of polystyrene-block-poly(ethylene oxide) (PS-b-PEO) block copolymer vesicles induced by supercritical carbon dioxide (scCO₂) is demonstrated. When PS-b-PEO block copolymer solutions in tetrahydrofuran (THF) are treated with scCO₂ at 70 °C for different times, PS-b-PEO copolymers first assemble into aggregated spheres; then aggregated spheres change into large compound micelles and finally evolve into vesicles. The possible formation mechanism of the vesicles is discussed.     

Preparation and characterization of graft copolymers of methyl methacrylate and poly(n-hexyl isocyanate) macromonomers

Living poly(n-hexyl isocyanate) (PHIC) was deactivated with methacryloyl chloride to produce methacryl-terminated poly(n-hexyl isocyanate) (PHIC-MA) rodlike macromonomers. Radical copolymerization of methyl methacrylate (MMA) with PHIC-MA was performed using 2,2′-azobis(isobutyronitrile) as an initiator in benzene at 60 °C to prepare poly(methyl methacrylate)-graft-poly(n-hexyl isocyanate) (PMMA-graft-PHIC) graft copolymers. The monomer reactivity ratios of MMA (M₁) and PHIC-MA (M₂) were evaluated as r₁=11.5 and r₂=∼0, exhibiting remarkably lower reactivity of PHIC-MA macromonomer than that of common macromonomers. The resultant graft copolymers were characterized using gel permeation chromatography equipped with low-angle laser light-scattering to determine the molecular weights, and equipped with a refractive index detector and an ultraviolet light detector to estimate a PHIC weight fraction of PMMA-graft-PHIC at the ith elution volume of the GPC chromatogram. There are 2-3 PHIC grafts per PMMA molecule, and the PHIC rodlike chains might be difficult to introduce into the PMMA main chains having higher molecular weights. A specific dimension of PMMA-graft-PHIC in solution was discussed in detail.     

Synthesis of amphiphilic triblock copolymers and application for morphology control of calcium carbonate crystals

A series of amphiphilic triblock copolymers poly(ethylene glycol)-block-poly(acrylic acid)-block-poly(n-butyl acrylate) (PEG-b-PAA-b-PnBA) differing only in the relative block lengths were synthesized by the acid-catalyzed elimination of the tert-butyl groups from poly(ethylene glycol)-block-poly(tert-butyl acrylate)-block-poly(n-butyl acrylate) (PEG-b-PtBA-b-PnBA), which was synthesized by atom-transfer radical polymerization (ATRP). The degree of polymerization, molecular weight and percentage of hydrolysis of the product PEG-b-PAA-b-PnBA were studied by gel permeation chromatography (GPC), NMR and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF-MS). Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to study the aggregation states of copolymers in water solution. The radii of the copolymer micelles shrink as Ca²⁺ is introduced into the solutions. The crystallization behaviors of calcium carbonate controlled by copolymer 1 (PEG₁₁₂-b-PAA₈₆-b-PnBA₆₀) and copolymer 2 (PEG₁₁₂-b-PAA₄₀-b-PnBA₇₂) differing mainly in the length of PAA block were systematically studied. It was found that the crystallization products are composed of calcite and vaterite, and the ratio of vaterite to calcite increases with increasing the concentration of copolymer 1. For copolymer 2, however, only calcite is obtained at all the concentration range investigated in this work.     

Synthesis and characterization of poly(ethylene glycol)-b-poly (l-lactide)-b-poly(l-glutamic acid) triblock copolymer

A biodegradable amphiphilic triblock copolymer of poly(ethylene glycol)-b-poly(l-lactide)-b-poly(l-glutamic acid) (PEG-b-PLLA-b-PLGA) was obtained by catalytic hydrogenation of poly(ethylene glycol)-b-poly(l-lactide)-b-poly(γ-benzyl-l-glutamic acid) (PEG-b-PLLA-b-PBLGA) synthesized by the ring-opening polymerization (ROP) of N-carboxyanhydride of γ-benzyl-l-glutamate (BLG-NCA) with amino-terminated MPEG-b-PLLA-NH₂ as a macroinitiator. MPEG-b-PLLA-NH₂ converted from MPEG-b-PLLA-OH first reacted with tert-Butoxycarbonyl-l-phenylalanine (Phe-^NBOC) and dicyclohexylcarbodiimide (DCC) and then deprotected the tert-butoxycarbonyl group. MPEG-b-PLLA-OH was prepared by ROP of l-lactide with monomethoxy poly(ethylene glycol) in the presence of stannous octoate. The triblock copolymer and its diblock precursors were characterized by ¹H NMR, FTIR, GPC and DSA (drop shape analysis) measurements. The lengths of each block polymers could be tailored by molecular design and the ratios of feeding monomers. The triblock polymer PEG-b-PLLA-b-PLGA containing carboxyl groups showed obviously improved hydrophilic properties and could be a good potential candidate as a drug delivery carrier.     

Branched poly(arylene ether ketone)s with tailored thermal properties: Effects of AB/AB2 ratio, core (B3) percentage, and reaction temperature

A series of poly(ether ketone) copolymers were prepared by nucleophilic aromatic polymerization reactions of the AB monomer 4-fluoro-4′-hydroxybenzophenone, 1, and the AB₂ monomer bis(4-fluorophenyl)-(4-hydroxyphenyl)phosphine oxide, 2, in the presence of 3 or 5 mol% of a highly reactive core molecule, tris(3,4,5-trifluorophenyl)phosphine oxide (B₃), 4. All of the copolymers prepared in the presence of a core molecule were sufficiently soluble in N-methylpyrrolidinone, NMP, to allow the determination of their molecular weights and polydispersity indices, PDIs. Number-average molecular weights, M_ns, of 3200-6800 Da were determined and the PDI values ranged from 1.41 to 4.07. The M_n was controlled by the mol% of 4 present in the reaction mixture with higher molar percentages leading to lower M_n values. Lower reaction temperatures and lower ratios of AB/AB₂ monomers afforded copolymers with lower PDI values. As expected, the crystallinity of the samples decreased with an increasing AB₂ content or an increase in PDI. The copolymers also exhibited excellent thermo-oxidative stability with a number of samples suffering 5% weight losses at temperatures, in air, well in excess of 450 °C.     

Dilute solutions and phase behavior of polydisperse A-b-(A-co-B) diblock copolymers

The effect of polydispersity on dilute solution properties and microphase separation of polydisperse high-molecular-weight (M_w > 10⁵ g mol⁻¹) polystyrene-block-poly(styrene-co-acrylonitrile) diblock copolymers, PS-block-P(S-co-AN), was studied in this work. For experiments, a series of diblock copolymers with variable weight fractions of acrylonitrile units (w_AN = 0.08-0.29) and length of block P(S-co-AN) was synthesized using nitroxide-mediated radical polymerization (NMP) technique, namely, by chain extension of nitroxide-terminated polystyrene (PS-TEMPO). According to light scattering and viscometry measurements in dilute tetrahydrofuran (THF) solutions the studied diblock copolymers assumed random coil conformation with the values of characteristic structure factor R_g/R_h = 1.50-1.76. It was found that polydisperse diblock copolymers being in strong segregation limit (SSL) self-assembled into microphase-separated ordered morphologies at ordinary temperature. The long periods of lamellar microdomains were larger compared to theoretical predictions for hypothetical monodisperse diblock copolymers. It was demonstrated by means of SAXS and TEM that a transition from a lamellar (LAM) to irregular face-centered-cubic (FCC) morphology occurred with increasing volume fraction of P(S-co-AN) block.     

Synthesis of polymeric prodrugs of chlorphenesin with saccharide branches by chemo-enzymatic regioselective strategy

A facile and regioselective enzymatic synthesis approach to prepare polymerizable lipophilic chlorphenesin vinyl esters was developed in this research. The influence of different organic solvents, enzyme sources, reaction time and the acylation reagent on the synthesis of chlorphenesin vinyl esters was investigated. Then the polymerizable monomers 1-O-vinylsuccinyl-chlorphenesin (OVSC) and 1-O-vinyladipoyl-chlorphenesin (OVAC) were homopolymerized using AIBN as the initiator. The obtained polymeric prodrugs were characterized with IR, NMR and GPC analyzes. The poly-OVSC has M_n of 1.35 × 10⁴ and M_w/M_n of 1.95, and the poly-OVAC has M_n of 2.37 × 10⁴ and M_w/M_n of 4.30. Moreover, 6-O-vinyladipoyl-d-glucose (OVAG), a biocompatible monomer, was copolymerized with OVSC and OVAC. Polymeric prodrugs of chlorphenesin with saccharide branches were successfully obtained with high molecular weight.     

Atom transfer radical polymerization of styrene initiated by 2-(4-chloromethyl-phenyl)-benzoxazole with high activity and fluorescent property

Functionalized polystyrene (PSt) was synthesized utilizing atom transfer radical polymerization (ATRP), which was conducted by using 2-(4-chloromethyl-phenyl)-benzoxazole (CMPB) as initiator, CuCl/PMDETA as catalyst, and cyclohexanone as solvent. The mechanism of ATRP was proved by characterizing the structure of PSt via ¹H NMR and preparing of PSt-b-PMMA block copolymer. The polymerization showed first order with respect to monomer concentration and relatively narrow polydispersity (M_w/M_n range from 1.30 to 1.50). Factors such as different reaction temperatures, mole ratio of monomer to initiator and so on, which can affect the ATRP system, were discussed in the paper. Moreover, CMPB showed high activity and could initiate styrene polymerization even at ambient temperature. The optical property of initiator was well preserved in the obtained PSt, and the end-functionalized PSt exhibited strong fluorescent emission at 351 nm.     

Synthesis and the effect of hydrophobic dodecyl end groups on pH-responsive micellization of poly(acrylic acid) and poly(ethylene glycol) triblock copolymer in aqueous solution

A pH-responsive triblock copolymer of poly(acrylic acid)-b-poly(ethylene glycol)-b-poly(acrylic acid) containing hydrophobic dodecyl end groups (C₁₂H₂₅-PAA-b-PEG-b-PAA-C₁₂H₂₅) with narrow molecular weight distribution (M _w/M _n?=?1.30) was synthesized via reversible addition-fragmentation chain transfer polymerization of acrylic acid (AA). Poly(ethylene glycol) (PEG) capped with S-1-dodecyl-S??-(??,????-dimethyl-????-acetic acid) trithiocarbonate (DDATC) end groups was used as the macro chain transfer agent (PEG macro-CTA) and 2,2??-azobisisobutyronitrile (AIBN) as initiator for monomer acrylic acid. The effect of the hydrophobic dodecyl end groups on pH-sensitive self-association of C₁₂H₂₅-PAA-b-PEG-b-PAA-C₁₂H₂₅ in aqueous solution was investigated by fluorescence spectroscopy, dynamic light scattering and atomic force microscope. At pH ??5.5, the solution behavior of C₁₂H₂₅-PAA-b-PEG-b-PAA-C₁₂H₂₅ is like polyelectrolyte in aqueous solution, and the effect of dodecyl end groups is negligible. At pH <5.0, the hydrophobic dodecyl end groups contribute dominantly to the pH-sensitive micellization and result in the formation of micelles with stronger hydrophobicity and larger size at low concentration (critical micelle concentration is 0.062?g/L). In the range of pH 2.5?C3.5, the steady (R _h????35.0?nm) and narrow size distributed micelles (polydispersity index, PDI?<?0.2) can be obtained. The micelles formed by C₁₂H₂₅-PAA-b-PEG-b-PAA-C₁₂H₂₅ triblock copolymer in acidic solution are expected to have a core?Cshell?Ccorona structure, where the hydrophobic dodecyl groups form the core, and weak hydrophobic PAA/PEG hydrogen-bonded complexes form the shell and the uncomplexed PAA, and PEG chain segments form the corona.     

Synthesis of poly(N-vinyl carbazole)-based block copolymers by sequential polymerizations of RAFT–ATRP

Poly(N-vinylcarbazole) (PNVK) is one of the extensively studied photoconductive polymers because of its wide ranges of applications. Through the reversible addition-fragmentation chain transfer/macromolecular design via the interchange of xanthates (RAFT/MADIX) polymerizations, in this study we investigated the syntheses of PNVK-based block copolymers (BCPs) with styrene (St) and methyl methacrylate (MMA). A variety of difunctional haloester-xanthate inifers were prepared and subjected to sequential polymerizations through RAFT and ATRP. In the presence of small amounts of bromoxanthate inifers, the ¹H NMR spectra showed nearly complete consumption of the NVK monomer, but without formation of PNVK. The bromoxanthate inifer could act as acidic moieties that protonated the highly basic NVK monomer. Through ¹H NMR and MALDI-TOF spectroscopic analyses, the structures of byproducts were indentified and a plausible mechanism for their formation was proposed. Alternatively, RAFT/MADIX polymerizations of NVK with two chloroxanthate inifers S-[1-methyl-4-(6-chloropropionate)ethyl acetate] O-ethyl dithiocarbonate and S-[1-methyl-4-(6-chloroisobutyrate)ethyl acetate] O-ethyl dithiocarbonate) provided first-order kinetic plots and well-controlled PNVK-Cl MIs (M_n ≈ 6000–40,000; M_w/M_n < 1.35). Using a suitable ATRP-initiating groups and optimization of the reaction conditions, the BCPs PNVK-b-PSt (M_n ≈ 4900–12,800; M_w/M_n < 1.5) and PNVK-b-PMMA (M_n ≈ 46,000–100,000; M_w/M_n < 1.35) were obtained.     

Synthesis of biodegradable poly(trans-4-hydroxy-N-benzyloxycarbonyl-l-proline)-block-poly(ε-caprolactone) copolymers and micellar characterizations

A series of novel types of diblock poly(trans-4-hydroxy-N-benzyloxycarbonyl-l-proline)-block-poly(ε-caprolactone) (PHpr10-b-PCL) copolymers were synthesized by ring-opening polymerization from macroinitiator poly(trans-4-hydroxy-N-benzyloxycarbonyl-l-proline) (PHpr10) and ε-caprolactone (ε-CL) in the presence of organocatalyst dl-lactic acid (dl-LA). The M_n of the copolymers increased from 3370 to 19,040 g mol⁻¹ with the molar ratio (10-100) of ε-CL to PHpr10. These products were characterized by differential scanning calorimetry (DSC), ¹H NMR, and gel permeation chromatography. According to DSC, the glass-transition temperature (T_g) of the diblock copolymers depend on the molar ratio of monomer/initiator that were added. The hydrolytic degradation behavior of PHpr-b-PCLs was evaluated from weight-loss measurements and the change of M_n and M_w/M_n. With higher PCL contents resulted in a slower weight loss, while having a higher molecular weight loss percentage. Their micellar characteristics in an aqueous phase were investigated by fluorescence spectroscopy, transmission electron microscopy (TEM), and dynamic light scattering (DLS). The block copolymers formed micelles in the aqueous phase with critical micelle concentrations (CMCs) in the range of 1.33-4.22 mg L⁻¹. The micelles exhibited a spindly shape and showed a narrow monodisperse size distribution. The obtained micelles have a relatively high drug-loading of about 26% when the feed weight ratio of amitriptyline hydrochloride (AM) to polymer was 1/1. An increase of molecular weight and hydrophobic components in copolymers produced a higher CMC value and greater loading efficiencies were observed.