Amphiphilic Multiblock Copolymers Research Articles

Biodegradable Hyperbranched Amphiphilic Polyurethane Multiblock Copolymers Consisting of Poly(propylene glycol), Poly(ethylene glycol), and Polycaprolactone as in Situ Thermogels

This paper reports the synthesis and characterization of new hyperbranched amphiphilic polyurethane multiblock copolymers consisting of poly(propylene glycol) (PPG), poly(ethylene glycol) (PEG), and polycaprolactone (PCL) segments as in situ thermogels. The hyperbranched poly(PPG/PEG/PCL urethane)s, termed as HBPEC copolymers, were synthesized from PPG-diol, PEG-diol, and PCL-triol by using 1,6-hexamethylene diisocyanate (HMDI) as a coupling agent. The compositions and structures of HBPEC copolymers were determined by GPC and 1H NMR spectroscopy. We carried out comparative studies of the new hyperbranched copolymers with their linear counterparts, the linear poly(PPG/PEG/PCL urethane) (LPEC) copolymer and Pluronic F127 PEG-PPG-PEG block copolymer, in terms of their self-assembly and aggregation behaviors and thermoresponsive properties. HBPEC copolymers were found to show thermoresponsive micelle formation and aggregation behaviors. Particularly, the lower critical solution temperature (LCST) of the copolymers was significantly affected by the copolymer architecture. HBPEC copolymers showed much lower LCST than LPEC, the linear counterpart. Our studies revealed that the effect of hyperbranch architecture was more prominent in the gelation of the copolymers. The aqueous solutions of HBPEC copolymers exhibited thermogelling behaviors at critical gelation concentrations (CGCs) ranging from 4.3 to 7.4 wt %. These values are much lower than those reported on other PCL-contained linear thermogelling copolymers and Pluronic F127 copolymer. In addition, the CGC of HBPEC copolymers is much lower than the control LPEC copolymer. More interestingly, at high temperatures, while LPEC and other linear thermogelling copolymers formed turbid sol, HBPEC formed a dehydrated gel. Our data suggest that these phenomena are caused by the hyperbranched structure of HBPEC copolymers, which could increase the interaction of copolymer branches and enhance the chain association through synergetic hydrogen bonding effect. The thermogelling behavior of HBPEC block copolymers was further evidenced by the 1H NMR molecular dynamic study and rheological study, which further support the above hypothesis. The hydrolytic degradation study showed that the HBPEC copolymer hydrogels are biodegradable under physiological conditions. Together with the good cell biocompatibility demonstrated by the cytotoxicity study, the new thermogelling copolymers reported in this paper could potentially be used as in situ-forming hydrogels for biomedical applications.

Controlled synthesis of multiblock copolymers by pseudoliving radical polymerization via the reversible addition-fragmentation chain-transfer mechanism

With the use of two classes of reversible addition-fragmentation chain-transfer agents—dithiobenzoates and trithiocarbonates—multiblock copolymers based on styrene and n-butyl acrylate, which are the best-studied monomers in these processes, are synthesized. It is shown that the polymers containing dithiobenzoate and trithiocarbonate groups are highly efficient for the synthesis of block copolymers, which is independent of the number of stages at which the polymeric RAFT agents are used in polymerization: In all cases, the polymeric RAFT agent is fully consumed in the polymerization of the “alien” monomer. The mechanism governing chain formation during the synthesis of multiblock copolymers, that is, the character of monomer insertion into the polymer chain, via one or both ends, is studied. It is found that the order of monomer loading determines the ratio of chains growing through one or two ends. The thermal stability of amphiphilic multiblock copolymers, their solubility in various solvents, and self-organizing ability are investigated.

Precise Synthesis of Amphiphilic Multiblock Copolymers by Combination of Acyclic Diene Metathesis (ADMET) Polymerization with Atom Transfer Radical Polymerization (ATRP) and Click Chemistry.

Various block (graft) copolymers have been prepared by combination of acyclic diene metathesis (ADMET) polymerization of 9,9-dialkyl-2,7-divinyl-fluorene with Cu-catalyzed atom transfer radical polymerization (ATRP) of styrene using macroinitiators prepared by introduction of initiating functionalities into poly(9,9-dialkylfluorene-2,7-vinylene)s (PFVs) chain ends: a precise synthesis of the amphiphilic ABCBA-type block copolymers has also been attained by subsequent combination with click reaction after modification of the chain end with NaN3.

Synthesis and characterization of novel biodegradable folate conjugated polyurethanes

In order to obtain targeting polyurethane micelle drug carriers, a series of biodegradable folate conjugated polyurethanes (FPUs) were synthesized using poly(ethylene glycol) (PEG) and poly(ε-caprolactone) (PCL) as soft segments, l-lysine ethyl ester diisocyanate (LDI) and 1,3-propanediol (PDO) as hard segments, and folic acid–ethylenediamine conjugate (FA–EDA) as an end-capping reagent. The resultant FPUs were fully characterized by 1H NMR, Fourier-transform infrared (FTIR) spectroscopy, ultraviolet spectrophotometry (UV), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). These polymers can self-assemble into micelles in aqueous solutions confirmed by dynamic light scattering (DLS), pyrene fluorescence probe techniques, and transmission electron microscopy (TEM). The results indicated that the bulk structures and micellar properties of the prepared polyurethanes could be controlled by varying the PEG content in the soft segments. The present work provides a facile approach to prepare amphiphilic multiblock copolymers with tumor targeting moiety, which is a good candidate as biodegradable carriers for active intracellular drug delivery.

Poly(Acrylic Acid-b-Styrene) Amphiphilic Multiblock Copolymers as Building Blocks for the Assembly of Discrete Nanoparticles.

In order to expand the utility of current polymeric micellar systems, we have developed amphiphilic multiblock copolymers containing alternating blocks of poly(acrylic acid) and poly(styrene). Heterotelechelic poly(tert-butyl acrylate-b-styrene) diblock copolymers containing an α-alkyne and an ω-azide were synthesized by atom transfer radical polymerization (ATRP), allowing control over the molecular weight while maintaining narrow polydispersity indices. The multiblock copolymers were constructed by copper-catalyzed azide-alkyne cycloaddition of azide-alkyne end functional diblock copolymers which were then characterized by (1)H NMR, FT-IR and SEC. The tert-butyl moieties of the poly(tert-butyl acrylate-b-styrene) multiblock copolymers were easily removed to form the poly(acrylic acid-b-styrene) multiblock copolymer ((PAA-PS)(9)), which contained up to 9 diblock repeats. The amphiphilic multiblock (PAA-PS)(9) (M(n) = 73.3 kg/mol) was self-assembled by dissolution into tetrahydrofuran and extensive dialysis against deionized water for 4 days. The critical micelle concentration (CMC) for (PAA-PS)(9) was determined by fluorescence spectroscopy using pyrene as a fluorescent probe and was found to be very low at 2 × 10(-4) mg/mL. The (PAA-PS)(9) multiblock was also analyzed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The hydrodynamic diameter of the particles was found to be 11 nm. Discrete spherical particles were observed by TEM with an average particle diameter of 14 nm. The poly(acrylic acid) periphery of the spherical particles should allow for future conjugation of biomolecules.

Micelle formation, gelation and phase separation of amphiphilic multiblock copolymers†

The phase behaviour of amphiphilic multiblock copolymers with a large number of blocks in semidilute solutions is studied by lattice Monte Carlo simulations. The influence on the resulting structures of the concentration, the solvent quality and the ratio of hydrophobic to hydrophilic monomers in the chains has been assessed explicitely. Several distinct regimes are put in evidence. For poorly substituted (mainly hydrophilic) copolymers formation of micelles is observed, either isolated or connected by the hydrophilic moieties, depending on concentration and chain length. For more highly substituted chains larger tubular hydrophobic structures appear which, at higher concentration, join to form extended hydrophobic cores. For both substitution ratios gelation is observed, but with a very different gel network structure. For the poorly substituted chains the gel consists of micelles cross-linked by hydrophilic blocks whereas for the highly substituted copolymers the extended hydrophobic cores form the gelling network. The interplay between gelation and phase separation clearly appears in the phase diagram. In particular, for poorly substituted copolymers and in a narrow concentration range, we observe a sol-gel transition followed by an inverse gel-sol transition when increasing the interaction energy. The simulation results are discussed in the context of the experimentally observed phase properties of methylcellulose, a hydrophobically substituted polysaccharide.

Synthesis and micelle behavior of (PNIPAm-PtBA-PNIPAm)m amphiphilic multiblock copolymer

A linear amphiphilic multiblock copolymer (PNIPAm-PtBA-PNIPAm)m was successfully synthesized by a two-step reversible addition–fragmentation transfer (RAFT) polymerization in the presence of a cyclic trithiocarbonate as RAFT agent. The micelle behavior of (PNIPAm-PtBA-PNIPAm)m multiblock copolymer in aqueous solution was then investigated by means of normal TEM, cryo-TEM, static and dynamic light scattering. The morphology, size, and size distribution of (PNIPAm-PtBA-PNIPAm)m micelles were found to be dependent on the initial concentration of multiblock copolymer in THF. Spherical micelles, associated aggregates of spherical micelles, cage-like micelles, layered structures, and vesicular micelles were experimentally observed, which were in good agreement with the prediction of theory and simulations on linear amphiphilic multiblock copolymer in selective solvent. The (PNIPAm-PtBA-PNIPAm)m micelles also exhibit thermo-sensitive behavior in aqueous solution because of the PNIPAm blocks.

Alternating Amphiphilic Multiblock Copolymers: Controlled Synthesis via RAFT Polymerization and Aqueous Solution Characterization

Four linear amphiphilic multiblock copolymers based on 2-(dimethylamino)ethyl methacrylate (DMAEMA, hydrophilic) and methyl methacrylate (MMA, hydrophobic), bearing from two to five blocks, were synthesized using reversible addition−fragmentation chain transfer polymerization and stepwise monomer additions. The degree of polymerization of each hydrophilic polyDMAEMA block was ∼50, while that of the hydrophobic polyMMA blocks was ca. 20. The stepwise monomer addition procedure secured that each higher multiblock was composed of its immediately lower homologue plus exactly one extra block. The molecular weights (MW) of the synthesized (co)polymers, as measured by gel permeation chromatography (GPC), were close to the theoretically expected. GPC also indicated rather narrow molecular weight distributions which, however, broadened with the number of blocks. The compositions of the copolymers, as determined by proton nuclear magnetic resonance spectroscopy, were also close to the expected values. The cloud poi...

Interfacial entrapment of noble metal nanoparticles and nanorods capped with amphiphilic multiblock copolymer at a selective liquid–liquid interface

An amphiphilic multiblock copolymer, [poly(4-vinylpyridine)-b-polystyrene-b-poly(4-vinylpyridine)](n) (P4VP-PS-P4VP)(n) bearing trithiocarbonate moieties (-S-CS-S-), was used as capping agent to fabricate the functional copolymer-capped Au nanoparticles. Due to the amphiphilic character of the multiblock copolymer, the (P4VP-PS-P4VP)(n)-capped Au nanoparticles were able to be entrapped and hence form a stable monolayer thin film at the (DMF-H(2)O)/diethyl ether interface. Note that DMF-H(2)O is a good mixed solvent for P4VP and a nonsolvent for PS, whereas diethyl ether is a good solvent for PS and a nonsolvent for P4VP. A similar procedure can be applied to prepare monolayer thin film of the (P4VP-PS-P4VP)(n)-capped Ag nanoparticles at the (DMF-H(2)O)/diethyl ether interface, which exhibits enhanced surface Raman signal. We further demonstrate that the stable monolayer of (P4VP-PS-P4VP)(n)-capped Au nanorods can also be fabricated by using the ligand-exchange method.

Rapid micropatterning by temperature-triggered reversible gelation of a recombinant smart elastin-like tetrablock-copolymer

We report a simple, fast, water-based method to obtain micropatterned biocompatible gels from a recently described family of elastin-like amphiphilic multiblock copolymers that combines reversible thermogelling properties under mild, physiological conditions with a means of replica molding.

Synthesis and Characterization of Amphiphilic Multiblock Copolymers: Effect of the Number of Blocks on Micellization

Five linear amphiphilic multiblock copolymers based on 2-(dimethylamino)ethyl methacrylate (“D”) and methyl methacrylate (“M”), bearing from two to six blocks, were synthesized using sequential group transfer polymerization. All copolymers were obtained from the same polymerization flask (by the withdrawal of a sufficient amount of sample and appropriate adjustment of subsequent monomer loadings) to ensure better comparison between the various multiblocks. A theoretical degree of polymerization (DPth) of 20 was targeted for all D blocks, whereas a DPth of 10 was aimed for the M blocks. Upon characterization using gel permeation chromatography and 1H NMR spectroscopy, the copolymers were confirmed to have the expected values of molecular weights and compositions. Subsequently, the aqueous micellization behavior of these copolymers was probed using dye solubilization, dynamic light scattering, and small-angle neutron scattering. Dye solubilization experiments indicated that micelles readily formed at low copolymer concentrations equal to or less than 0.03% w/w. The scattering measurements revealed that despite the differences in their overall DPth values, the triblock, the tetrablock, and the pentablock copolymers self-assembled in water to form micelles with radii of gyration and hydrodynamic radii very similar to each other, suggesting chain looping and the formation of flowerlike micelles, which is in agreement with recent Monte Carlo simulations.

Synthesis of amphiphilic multiblock and triblock copolymers of polydimethylsiloxane and poly(N,N‐dimethylacrylamide)

AbstractThe synthesis and spectroscopic characterization of a new family of amphiphilic multiblock and triblock copolymers is described. The synthetic methodology rests on the preparation of telechelic multifunctional and difunctional chain transfer agents easily available in two synthetic steps from commercially available polydimethylsiloxane‐containing starting materials. Telechelic polymers thus synthesized are used as macromolecular chain transfer agents in the reversible addition fragmentation chain transfer (RAFT) polymerization of N,N‐dimethylacrylamide (DMA) enabling the synthesis of (AB)n‐type multiblock and ABA‐type triblock copolymers of varying compositions possessing monomodal molecular weight distribution. (AB)n multiblock copolymers [(PDMA‐b‐PDMS)n] were prepared with between 52 and 95 wt % poly(dimethylacrylamide) with number average molecular weights (Mn) between 14,000 and 86,000 (polydispersities of 1.20–2.30). On the other hand, ABA block copolymers with DMA led to amphiphilic block copolymers (PDMA‐b‐PDMS‐b‐PDMA) with Mn values between 9000 and 44,000 (polydispersities of 1.24–1.62). © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7033–7048, 2008

Amphiphilic multiblock copolymer stabilized Au nanoparticles

Abstract Stable gold nanoparticles (AuNPs) are synthesized in N , N -dimethylformamide (DMF) by using amphiphilic multiblock copolymer (P4VP–PS–P4VP) n containing multiple trithiocarbonate moieties or amphiphilic triblock copolymer (HS–P4VP–PS–P4VP–SH) with thiol end groups as protecting agents. Only isolated gold nanoparticles are obtained, which indicate that the multiple functional groups of a single polymer chain are grafted at the same time to the same nanoparticle. The sizes of the AuNPs are slightly increased with raising the concentration of gold salt for a given concentration of the copolymers, leading to the red shift of the surface plasmon resonance of the AuNPs. Fourier transform infrared (FTIR) spectra and scanning force microscopy (SFM) images confirm that the AuNPs are indeed wrapped by the block copolymers. With the amphiphilic characteristic of the block copolymers, the AuNPs can be successfully transferred from DMF into aqueous solution. An unexpected red shift of the surface plasmon resonance (SPR) of the AuNPs after solvent transfer is observed, which is mainly attributed to the dense protecting polymer layers on the surfaces of the AuNPs in aqueous solutions. Both the size and structure of nanoparticles are maintained after solvent transfer. The AuNPs in aqueous solutions can be stable for a wide range of pH value up to pH ≈ 9. At strong basic condition with pH > 10, the AuNPs will aggregate. The effect of pH value on the stability of the AuNPs is reversible. The optical property of the AuNPs also slightly depends on the pH value.

Multiblock poly(4‐vinylpyridine) and its copolymer prepared with cyclic trithiocarbonate as a reversible addition–fragmentation transfer agent

AbstractThe polymerization of 4‐vinylpyridine was conducted in the presence of a cyclic trithiocarbonate (4,7‐diphenyl‐[1,3]dithiepane‐2‐thione) as a reversible addition–fragmentation transfer (RAFT) polymerization agent, and a multiblock polymer with narrow‐polydispersity blocks was prepared. Two kinds of multiblock copolymers of styrene and 4‐vinylpyridine, that is, (ABA)n multi‐triblock copolymers with polystyrene or poly(4‐vinylpyridine) as the outer blocks, were prepared with multiblock polystyrene or poly(4‐vinylpyridine) as a macro‐RAFT agent, respectively. GPC data for the original polymers and polymers cleaved by amine demonstrated the successful synthesis of amphiphilic multiblock copolymers of styrene and 4‐vinylpyridine via two‐step polymerization. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2617–2623, 2007

Synthesis of (ABCB) n type ternary amphiphilic multiblock copolymer via poly(ethylene oxide) macro-chain transfer agent

A novel (ABCB) n type ternary amphiphilic multiblock copolymer was synthesized by stepwise insertion of monomers into the trithiocarbonate-embedded poly(ethylene oxide) (PEO) macro-chain transfer agent (PEO-CTA) n . (PEO-CTA) n was synthesized first by coupling of α,ω-dihydroxyl PEO with dicarboxylic trithiocarbonate, then styrene (St) and t-butyl acrylate ( t BA) were inserted into the (PEO-CTA) n successively to yield (PEO- b-PS) n and (PEO- b-PS- b-P t BA- b-PS) n , respectively. After hydrolysis of the (PEO- b-PS- b-P t BA- b-PS) n , the final product (PEO- b-PS- b-PAA- b-PS) n was obtained.

Synthesis and self‐assembly morphologies of amphiphilic multiblock copolymers [poly(ethylene oxide)‐b‐polystyrene]n via trithiocarbonate‐embedded PEO macro‐RAFT agent

AbstractAn amphiphilic multiblock copolymer [poly(ethylene oxide)‐b‐polystyrene]n [(PEO‐b‐PS)n] is synthesized by using trithiocarbonate‐embedded PEO as macro‐RAFT agent. PEO with four inserted trithiocarbonate (Mn = 9200 and Mw/Mn = 1.62) groups is prepared first by condensation of α, ω‐dihydroxyl poly(ethylene oxide) with S, S′‐Bis(α, α′‐dimethyl‐α″‐acetic acid)‐trithiocarbonate (BDATC) in the presence of pyridine, then a series of goal copolymers with different St units (varied from 25 to 218 per segment) are obtained by reversible addition‐fragmentation chain transfer (RAFT) polymerization. The synthesis process is monitored by size exclusion chromatography (SEC), 1H NMR and FT‐IR. The self‐assembled morphologies of the copolymers are strongly dependent of the length of PS block chains when the chain length of PEO is fixed, some new morphologies as large leaf‐like aggregates (LLAs), large octopus‐like aggregates (LOAs), and coarse‐grain like micelles (CGMs) are observed besides some familiar aggregates as large compound vesicles (LCVs), lamellae and rods, and the effect of water content on the morphologies is also discussed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6071–6082, 2006

Aminooxy Pluronics: Synthesis and Preparation of Glycosaminoglycan Adducts

Novel biomaterials have been prepared in which glycosaminoglycans (GAGs) are chemically modified to create amphiphilic multiblock copolymers that are able to adhere to hydrophobic surfaces and can self-assemble into cross-linker-free hydrogels. First, the triblock poly(ethylene oxide)-polypropylene oxide copolymers (Pluronics) were converted into the previously unknown aminooxy (AO) derivatives. Both mono-AO and bis-AO Pluronics (AOPs) were synthesized and fully characterized in order to prepare tetrablock and pentablock copolymers, respectively. Second, the AOPs were coupled to the uronic acid carboxylates of heparin (HP) and hyaluronic acid (HA) using carbodiimide chemistry in order to give the previously undescribed amidooxy GAG derivatives. The coupling chemistry was confirmed using a newly prepared fluorescent AO reagent. Third, AOP-heparin and AOP-fluorescently labeled heparin were shown to adsorb efficiently to polystyrene surfaces, as determined by IL-8 based ELISA and fluorescence measurements, respectively. Fourth, AOP-linked fluorescently labeled HA was shown to adsorb efficiently to plastic surfaces. Finally, three different AOPs were evaluated for self-assembling hydrogel formation by AOP-HA pentablock polymers. In short, AOP-GAG adducts are semisynthetic amphiphilic biomacromolecules that offer a range of valuable practical opportunities for surface modification, preparation of cross-linker-free hydrogels, and formation of self-assembling mimics of the extracellular matrix.

Microspheres Made of Poly(ε‐caprolactone)‐Based Amphiphilic Copolymers: Potential in Sustained Delivery of Proteins

Microspheres of amphiphilic multi-block poly(ester-ether)s (PEE)s and poly(ester-ether-amide)s (PEEA)s based on poly(epsilon-caprolactone) (PCL) were investigated as delivery systems for proteins. The interest was mainly focused on the effect of their molecular structure and composition on the overall properties of the microspheres, encapsulating bovine serum albumin (BSA) as a model protein. PEEs and PEEAs were prepared using a alpha,omega-dihydroxy-terminated PCL macromer (Mn= 2.0 kDa) as a hydrophobic component. Hydrophilic oxyethylene sequences were generated using poly(ethylene oxide)s (PEO)s of different molecular mass (Mn= 300-600 Da) in the case of PEEs, or 4,7,10-trioxa-1,13-tridecanediamine (Trioxy) and PEO150 (Mn= 150 Da) in the case of PEEAs. The copolymers showed a decrease of Tm and crystallinity values as compared with PCL. Within each class of copolymers, the bulk hydrophilicity increased with increasing the number of oxyethylene groups in the chain repeat unit. PEEAs were more hydrophilic than PEEs with a similar number of oxyethylene groups. Discrete spherical particles were prepared by both PEEs and PEEAs and their BSA encapsulation efficiency related to copolymer properties. Interestingly, the insertion of short hydrophilic segments is enough to significantly affect protein distribution inside microspheres and its release profiles, as compared to PCL microspheres. Different degradation rates and mechanisms were observed for copolymer microspheres, mainly depending on the distribution of oxyethylene units along the chain. The results highlight that a fine control over the structural parameters of amphiphilic PCL-based multi-block copolymers is a key factor for their application in the field of protein delivery.

Interpolymer complexes between hydrophobically modified poly(methacrylic acid) and poly( N-vinylpyrrolidone)

The formation and structure of interpolymer complexes between amphiphilic multi-block copolymers—poly(dimethylsiloxane- N-vinylpyrrolidone) and poly(dimethylsiloxane-methacrylic acid)—were studied using potentiometric and conductometric titration, viscometry and fluorescence spectroscopy. The ratio of hydrophobic/hydrophilic groups in the copolymer and the molecular weight of each sequence were varied in order to establish the influence of these parameters on the interactions between the components. The complexation between pairs of block copolymers, of block copolymers and homopolymers as well as between homopolymer pairs was considered. The complexes were formed through the hydrogen bonding. They have a compact structure with a non-stoichiometric composition of pyrrolidone to methacrylic acid groups ratio around 0.6–0.7, with the exception of complexes formed between pairs of homopolymers and of copolymers with the shortest siloxane block. The difference between the new complexes and the ones formed from homopolymers, with equimolar composition, is explained by the spatial non-complementarity of the copolymers having a ‘flower-like’ structure in aqueous solutions.

Precise Synthesis of Amphiphilic Polymeric Architectures by Grafting Poly(ethylene glycol) to End-Functionalized Block ROMP Copolymers

Various (linear, triarms, ABA or ABCBA type) amphiphilic multiblock copolymers containing acetal-protected sugars have been prepared by the coupling of an end-functionalized ROMP copolymer with poly(ethylene glycol) (PEG). The synthesis involves three key steps: (i) termination of the block ROMP copolymer prepared by molybdenum−alkylidene initiator, [Mo(CHCMe2Ph)(N-2,6-iPr2C6H3)(OtBu)2] (1), with either TMS (SiMe3) protected 4-hydroxy- or 3,5-dihydroxybenzaldehyde; (ii) exclusive removal of the TMS protection from the terminus; and (iii) the potassium hydride mediated attachment of poly(ethylene glycol), PEG (Mn = 2200 or 4600), to the ring-opened polymers. In all cases, Mn values for resultant copolymers estimated by 1H NMR (and by GPC) were very close to those calculated based on the initial monomer/initiator loadings with low polydispersity indices (Mw/Mn = 1.05−1.20 by GPC). The preparation of a multiblock or star-shaped (triarms) amphiphilic copolymer was possible depending on which terminating agent was adopted. The cyclic acetal in the sugar-containing polymers could be hydrolyzed exclusively using a CF3CO2H/H2O mixture (9/1 v/v) affording the corresponding deprotected analogues with the Mn values calculated based on the initial molar ratios.