Three-arm Poly Research Articles

Preparation of Degradable and Transformable Core-Corona-Type Particles that Control Cellular Uptake by Thermal Shape Change.

Particle-cell interactions, such as cellular uptake, vary depending on the particle size, shape, and surface properties. By dynamic control of the physical properties of particles, microparticle-cell interactions can intentionally be altered. Particle degradability is also necessary for their application in the body. In this study, we aimed to prepare degradable core-corona-type particles that are deformed near the body temperature and investigated particle shape-dependent cellular uptake. Degradable and transformable particles consisting of poly(2-methylene-1,3-dioxepane)-co-poly(ethylene glycol) with three-armed poly(ε-caprolactone) (PCL) were prepared. The particle melting point was controlled by the chain length of the three-armed PCL. Particle degradation occurred under both acidic and alkaline conditions via ester group hydrolysis in the polymer backbones. The rod-shaped microparticles prepared by uniaxial stretching at a temperature above the melting point of the core showed less uptake into macrophages than did the spherical microparticles. Therefore, the degradable transformable particles enable macrophage interaction control via stimuli-regulated particle shapes and are expected to be applied as drug delivery carriers that can be decomposed and excreted from the body.

In Vitro and In Vivo Degradation of Photo-Crosslinked Poly(Trimethylene Carbonate-co-ε-Caprolactone) Networks.

Three-armed poly(trimethylene carbonate) (PTMC) and poly(trimethylene carbonate-co-Ɛ-caprolactone) (P(TMC-co-ε-CL)) macromers with molecular weights of approximately 30kgmol-1 are synthesized by ring-opening polymerization and subsequent functionalization with methacrylic anhydride. Networks are then prepared by photo-crosslinking. To investigate the in vitro and in vivo degradation properties of these photo-crosslinked networks and assess the effect of ε-caprolactone content on the degradation properties, PTMC networks, and copolymer networks with two different TMC:ε-CL ratios are prepared. PTMC networks degraded slowly, via an enzymatic surface erosion process, both in vitro and in vivo. Networks prepared from P(TMC-co-ε-CL) macromers with a 74:26 ratio are found to degrade slowly as well, via a surface erosion process, albeit at a higher rate compared to PTMC networks. Increasing the ε-CL content to a ratio of 52:48, resulted in a faster degradation. These networks lost their mechanical properties much sooner than the other networks. Thus, PTMC and P(TMC-co-ε-CL) networks are interesting networks for tissue engineering purposes and the exact degradation properties can be tuned by varying the TMC:ε-CL ratio, providing researchers with a tool to obtain copolymer networks with the desired degradation rate depending on the intended application.

Construction of gas permeable channel in poly(l-lactic acid) membrane and its control of the micro atmosphere in okra packaging

An atmosphere within a package affects the metabolic process of food and the microbial growth of fresh products and has a vital role in preserving food. It depends on the membrane's specific gas permeability and selectivity to generate a desirable atmosphere for storage. In this study, triblock poly(l-lactic acid‑d-ɛ-caprolactone) (PLDC) copolymers and three-arm poly(l-lactic acid-g-ɛ-caprolactone) (PLGC) star copolymers were synthesized, in which a microphase-separated morphology of sea-island structure was established in PLGC membrane as a gas “fast permeation channel” for regulating CO2 and O2 permeability and CO2/O2 selectivity. AFM observation revealed different well-defined micro phase-separated structures of PLGC with size ranges of 200– 300 nm. Comparing PLGC membrane with PLLA, CO2 and O2 transmission rates increased by 416.9 % and 132.7 %, while H2O transport rates increased by 245.6 %. Mechanical testing shows that the PLGC membrane exhibits 40.8-fold elongation at break compared to PLLA, showing excellent flexibility. Moreover, okra's equilibrium-modified atmosphere packaging was designed based on a theoretically derived model. Preservation results suggested that the PLGC packaging membrane could generate an ideal high 8.7– 9.2 % CO2 and low 2.3– 2.7 % O2 atmosphere for okra preservation, delaying the discoloring and rotting of okra.

Photo-crosslinked anhydride-modified polyester and –ethers for pH-sensitive drug release

Photo-crosslinkable polymers have a great potential for the delivery of sensitive drugs. They allow preparation of drug releasing devices by photo-crosslinking, thus avoiding high processing temperatures. In this study, the hydrolysis behavior and drug release of three different photo-crosslinkable poly(ether anhydride)s and one poly(ester anhydride) were investigated. Three-arm poly(ethylene glycol) or polycaprolactone was reacted with succinic anhydride to obtain carboxylated macromers, and further functionalized with methacrylic anhydride to form methacrylated marcromers with anhydride linkages. The synthetized macromers were used to prepare photo-crosslinked matrices with different hydrolytic degradation times for active agent release purposes.The hydrolysis was clearly pH-sensitive: polymer networks degraded slowly in acidic conditions, and degradation rate increased as the pH shifted towards basic conditions. Drug release was studied with two water-soluble model drugs lidocaine (234 mol/g) and vitamin B12 (1355 g/mol). Vitamin B12 was released mainly due to polymer network degradation, whereas smaller molecule lidocaine was released also through diffusion and swelling of polymer network. Only a small amount of vitamin B12 was released in acidic conditions (pH 1.3 and pH 2.1). These polymers have potential in colon targeted drug delivery as the polymer could protect sensitive drugs from acidic conditions in the stomach, and the drug would be released as the conditions change closer to neutral pH in the intestine.

Ion conductive polymer electrolyte membranes based on star-branched poly(ethylene-glycol tri-acrylate) and polysulfide macromonomers

This article presents star-branched polymeric co-networks consisting of a three-arm poly(ethylene glycol) acrylate macromonomers (PEG3A) and a three-arm polysulfide (PS) via UV photopolymerization for the development of ion conductive polymer electrolyte membrane (PEM) containing succinonitrile (SCN) plasticizer and lithium bis(trifluoromethane sulfonyl)imide (LITFSI) salt. The hyperbranched co-network (PS-co-PEG3A) exhibits a lower glass transition temperature (Tg = −49 °C at 50:50) relative to that of 3-arm (PEG3A), i.e., Tg of −32 °C, showing systematic variation with polysulfide addition. In the tensile tests, elongation-at-break of PEM – PS-co-PEG3A is higher, but it occurs at the expense of lower tensile strength and modulus. Moreover, PEM – PEG3A exhibits higher strength and modulus relative to those of PEM – PS-co-PEG3A copolymer, but its ionic conductivity is lower (i.e., 3.41 × 10−4 S/cm for PEM – PEG3A versus 1.35 × 10−3 S/cm for PEM – PS-co-PEG3A at 21 °C). This improved ionic conductivity may be attributed to reduced crosslinking density associated with the formation of SC bonds upon addition of polysulfide. The PEM – PS-co-PEG3A co-network is thermally stable up to 130 °C tested and exhibited reasonably good anodic stabilities up to 4.5 V versus Li/Li+. In the CV tests in half-cells configuration with LiFePO4 cathode against Li/Li+, the specific discharge capacity was found to be 120 mAh/g with capacity retention of about 97% for 50 cycles tested.

Synthesis of Inorganic Silica Grafted Three-arm PLLA and Their Behaviors for PLA Matrix

The low melt strength and poor crystallization behavior severely limit the processing and application of poly(lactic acid) (PLA) as biodegradable film materials. In this work, three-arm poly(L-lactic acid) (3A-PLLA) grafted silica nanoparticles with two kinds of topology structures were introduced into PLA matrix to improve the biodegradation performance. Different methods were used to characterize the structure of the grafted 3A-PLLA chains, the grafting density, and the thermal decomposition behavior of the nanoparticles. By varying the mass ratios of raw materials and altering the order of dropping solution in the reaction, high grafting densitytangled 3A-PLLA grafted SiO2 was synthesized as “3A-PLLA grafting to SiO2” (GTS), while low grafting density-stretched 3A-PLLA grafted SiO2 was obtained as “SiO2 grafting to 3A-PLLA” (GTA). Topology of nanoparticles as well as the filler-matrix interaction is critically important to structure bio-nanocomposites with desirable properties. Thus, the GTS and GTA nanoparticles were introduced into PLA matrix to assess the effect. The SEM images showed the uniform dispersion of the modified nanoparticles, while the shear rheology results revealed that GTA nanoparticles made a more significant contribution on the melt-strengthening and relaxation time-extension of PLA. Moreover, it is suggested that GTA nanoparticles were more effective to act as a nucleating agent for PLA, which was proved by differential scanning calorimetry (DSC) and polarized optical microscopy (POM) researches. All of the improvements mentioned above of GTA nanocomposites can be ascribed to stronger entanglements between 3A-PLLA stretched by nano-SiO2 and PLA matrix.

Preparation of Designed Poly(trimethylene carbonate) Meniscus Implants by Stereolithography: Challenges in Stereolithography.

Three-armed poly(trimethylene carbonate) macromers with a relatively high molecular weight of 28.9 kg mol-1 are prepared by ring opening polymerization and subsequent functionalization with methacrylate end groups. A resin suitable for processing by stereolithography is developed using propylene carbonate as a diluent, a photoinitiator, and a dye to control the curing characteristics. The difficulties in building designed structures with digital light processing stereolithography and the ways of optimizing the resin compositions are described in detail. Using an optimized resin composition, which contained 50 wt% macromer, 50 wt% diluent, 0.05 wt% (relative to the macromer) dye, and 5 wt% (relative to the macromer) photoinitiator, designed 3D porous structures with a gyroid pore network geometry are manufactured. By varying pore sizes and porosities between, respectively, 300 and 1000 μm and 60% and 90%, cylindrical porous poly(trimethylene carbonate) network structures with compression moduli of 85-2320 kPa are prepared. A porous poly(trimethylene carbonate) network meniscus implant is designed on the basis of computed tomography imaging data. By adjusting the characteristics of the gyroid pore architecture, an implant with a compression modulus close to 400 kPa, which fits the compression modulus of human meniscal tissue, is manufactured by stereolithography.

A simple and fast formation of biodegradable poly(urethane-urea) hydrogel with high water content and good mechanical property

Abstract The synthesis of biodegradable hydrogels with both good mechanical properties and high water content is still a great challenge. In this study, a simple and scalable strategy for the preparation of a biodegradable polyurethane prepolymer composed of isocyanate terminated linear polyethylene glycol (L-PEG) and isocyanate terminated three-armed poly( l -lactic acid) (T-PLLA) is described. When mixed with water, the prepolymer forms a poly(urethane-urea) hydrogel in few minutes. The effect of the molecular weight and the feeding ratio of L-PEG and T-PLLA on the mechanical property of the poly(urethane-urea) hydrogel is discussed. The resulting hydrogel shows good mechanical properties with high tensile strength (up to 108 KPa) and recorded elongation rate (4500%), while maintaining high water content (up to 91% mass ratio). Meanwhile, the maximum water retaining capacity of the hydrogel can be up to 38 times of PU prepolymer (in mass), which is equal to 97.4% water content. Its degradation property is analyzed by the loss of tensile strength and cross section morphology through SEM with time. Such a low cost and biodegradable poly(urethane-urea) hydrogel, which combines fast hydrogel formation, high water content and good mechanical properties, might be used as potential candidates for applications in agrological field, such as sand fixing in desertification control.

高分子量立构复合结晶的三枝化PPO-PDLA-PLLA嵌段共聚物

以三枝化低不饱和度聚环氧丙烷（PPO）引发 D -丙交酯（ D -LA）逐步开环聚合，合成了三枝化聚环氧丙烷-聚右旋乳酸（PPO-PDLA）共聚物. 用辛酸亚锡Sn（Oct） 2 与PPO-PDLA端羟基反应进行Sn（Oct）封端，制备了三枝化PPO-PDLA-Sn（Oct）预聚物. 再于130 ℃下，以其作为大分子引发剂与 L -丙交酯（ L -LA）开环聚合，合成了分子量>10 5 的三枝化PPO-PDLA-PLLA嵌段共聚物. 活性端基的引入，降低了聚合反应温度，从而降低了聚合中的酯交换或热降解反应发生的概率. 实现了高分子量PPO-PDLA-PLLA嵌段共聚物的合成. 结构测试结果表明，合成的嵌段共聚物具有分子结构易控及立构规整度高等特点. 在结晶-熔融-再结晶重复热处理下，三枝化PPO-PDLA-PLLA嵌段共聚物仅发生立构复合聚乳酸结晶，且结晶能力稳定.

Stereocomplexed three-arm PPO–PDLA–PLLA copolymers: Synthesis via an end-functionalized initiator

Three-arm poly (propylene oxide)-block-poly (d-lactic acid) (PPO–PDLA) copolymers were successfully synthesized by ring-opening polymerization (ROP) of d-lactide using three-arm poly (propylene oxide) as a macroinitiator. PPO–PDLA copolymers were then functionalized with three ending tin (II)-alkoxide groups, and those functionalized copolymers could act as efficient initiators in polymerization of l-lactide at relative low temperature. The combination of proton nuclear magnetic resonance spectroscopy and matrix-assisted laser desorption/ionization time-of-flight mass spectrometer supported their structures of ending tin (II)-alkoxide groups. A series of novel three-arm poly (propylene oxide)-block-poly (d-lactic acid)-block-poly (l-lactic acid) (PPO–PDLA–PLLA) copolymers with high molecular weight (Mn>2.0×105) and equivalent D-LA/L-LA compositions, were synthesized using those functionalized initiators in polymerization of l-lactide at 130°C. The results show that PPO–PDLA–PLLA copolymers are highly stereoregularity, and the molecular weight of enantiomeric block reaches up to 8.0×104. Those three-arm PPO–PDLA–PLLA copolymers exhibit exclusive stereocomplex crystallization behavior with a high melting temperature about 207°C.

Photocrosslinkable bioadhesive based on dextran and PEG derivatives

In this study, a hybrid photopolymeric bioadhesive system consisting of urethane methacrylated dextran (Dex-U) and 3, 4-Dihydroxyphenyl-l-alanine (DOPA) modified three-arm poly (ethylene glycol) s (PEG-DOPAs) was designed. The process of photopolymerization was detected by Photo-Differential Scanning Calorimetry (Photo-DSC). The adhesion strength was evaluated by the lap shear tests. The surface tension of the solutions, burst pressures and the cytotoxicity assays were also investigated. The addition of PEG-DOPAs significantly improved the properties of Dex-U especially in the field of adhesion strength and burst pressure. And materials variation could be tailored to match the demands for tissue repair. Compared to the Dex-U systems, the maximum adhesion strength of the copolymeric system increased from 2.7±0.1MPa to 4.0±0.6MPa. Owing to its strong adhesion strength, rapid curing rate and good biocompatibility, such photocrosslinkable hydrogelsa could be applied to the areas of bioadhesive.

Modified PLA Homochiral Crystallites Facilitated by the Confinement of PLA Stereocomplexes

The crystallization and melting behaviors of polylactide (PLA) homochiral polymer under the confinement of stereocomplex crystallites were studied in the linear and three-armed poly(d-lactide)/poly(l-lactide) (PDLA/PLLA and 3PDLA/3PLLA) solution casting blends. WAXD results showed that novel modified crystallites formed when PLA homopolymer crystallized from the melting state. And the modified crystallites formed in 3PDLA/3PLLA blends (M-A) were less stable than that formed in similar PDLA/PLLA blends (M-B) after specimens cooled at a specific rate. Although these modified crystallites differed from PLA α crystallites (M-C), both of them transformed into α crystallites during heating. The transitions among different crystallites revealed the multiple melting behaviors in DSC measurement. The type of PLA homochiral crystallites and their contents mainly depended on the D/L compositions, annealing conditions, molecular weights, and architectures of the polymers in the blends. The formation of these modified...

Study on the synthesis and properties of mussel mimetic poly(ethylene glycol) bioadhesive

The catecholic amino acid 3,4-Dihydroxyphenyl-l-alanine (DOPA) is believed to be responsible for the water-resistant adhesive characteristics of mussel adhesive proteins (MAPs). In this paper, the synthesis of three-armed poly(ethylene glycol)s with dopamine endgroups (PEG–DOPAs) using acylation reaction and Michael addition reaction was described, and PEG–DOPAs was used as bioadhesive under the UV irradiation. The structures of PEG–DOPAs were characterized by FTIR, 1H NMR spectroscopy. The adhesion properties of PEG–DOPAs were investigated and results were significantly superior to 0.05MPa of the commercially available fibrin adhesives. Moreover, the adhesive strength of PEG–DOPAs (Mw 3000) increased from 0.587MPa to 1.82MPa, PEG–DOPAs (Mw 20,000) increased from 0.338MPa to 1.92MPa with the elongation of the binding time, severally. The photopolymerization kinetic study was taken to evaluate gelation time of bioadhesive indirectly. The cytotoxicity of photocured PEG–DOPAs hydrogels for L929 cells was evaluated by the fluorescence microscopy and MTT (3-[4-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide; Thiazolyl blue) assay, respectively. The results showed that PEG–DOPAs were biocompatible and less cytotoxicity toward the growth of L929 cells. The swelling properties of PEG–DOPAs hydrogels were also tested. PEG–DOPAs (3000) reached swelling equilibrium within 2h at 37°C, and PEG–DOPAs (20,000) within 6h at 37°C.

Cross-linked poly(2,5-benzimidazole) consisting of wholly aromatic groups for high-temperature PEM fuel cell applications

Cross-linked poly(2,5-benzimidazole) (C-ABPBI) membranes consisting of wholly aromatic groups were prepared by a reaction between three-arm poly(2,5-benzimidazole)s with three carboxylic acid end groups (T-ABPBI) and 3,3′-diaminobenzidine (DABI) in poly(phosphoric acid) (PPA) during the casting process. T-ABPBI was prepared by the polymerization of 3,4-diaminobenzoic acid and 1,3,5-benzenetricarboxylic acid in PPA, and the polymerization solution was directly used for the casting process. The cross-linking process improved the chemical stability of the host polymer, poly(2,5-benzimidazole) (ABPBI). The C-ABPBI membranes could contain a larger phosphoric acid (PA) content than the membranes of linear polybezimidazoles, such as ABPBI and poly[2,2′-( m-phenylene)-5,5′-bibenzimidazole]. Consequently, the C-ABPBI membranes showed higher proton conductivity values than the linear polymer membranes. For example, the C-ABPBI-50 membrane could contain a PA content >84 wt.% with a proton conductivity of 0.12 S cm −1 at 150 °C under anhydrous conditions.

Thermo-responsive fluorescent micelles from amphiphilic A3B miktoarm star copolymers prepared via a combination of SET-LRP and RAFT polymerization

A novel amphiphilic A3B miktoarm star copolymer poly(N-isopropylacrylamide)3-poly(N-vinylcarbazole) ((PNIPAAM)3(PVK)) was successfully synthesized by a combination of single-electron transfer living radical polymerization (SET-LRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization. First, the well-defined three-armed poly(N-isopropylacrylamide) (PNIPAAM)3 was prepared via SET-LRP of N-isopropylacrylamide in acetone at 25 °C using a tetrafunctional bromoxanthate iniferter (Xanthate-Br3) as the initiator and Cu(0)/PMDETA as a catalyst system. Secondly, the target amphiphilic A3B miktoarm star copolymer ((PNIPAAM)3(PVK)) was prepared via RAFT polymerization of N-vinylcarbazole (NVC) employing (PNIPAAM)3 as the macro-RAFT agent. The architecture of the amphiphilic A3B miktoarm star copolymers were characterized by GPC, 1H-NMR spectra. Furthermore, the fluorescence intensity of micelle increased with the temperature and had a good temperature reversibility, which was investigated by dynamic light scattering (DLS), fluorescent and UV-vis spectra. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4268–4278, 2010

Development of Electrospun Three‐arm Star Poly(ε‐caprolactone) Meshes for Tissue Engineering Applications

We have developed three-dimensional electrospun microfibrous meshes of a novel star branched three-arm poly(ε-caprolactone) (*PCL) as potential scaffolds for tissue engineering applications. The processing conditions required to obtain uniform fibers were optimized by studying their influence on fiber morphology and size. Polymer molecular weight and solution feed rate influenced both the mesh microstructure and the tensile properties of the developed mats. Electrospun samples were also tested for their mechanical properties in wet conditions, showing higher yield strength and strain in comparison to that observed in dry conditions. Cell culture experiments employing MC3T3-E1 osteoblast like cells showed good cell viability adhesion and collagen production on the *PCL scaffolds.

Influence of AlCl_3 on the optical properties of new synthesized 3-armed poly(methyl methacrylate) films

Three-armed poly(methyl methacrylate)[PMMA] was synthesized by atom transfer radical polymerization at 100 °C using benzene-1,3,5-triyl tris(4-(bromomethyl) benzoate as 3-armed initiator and a cuprous(I) bromide/2,2'-bipyridine catalytic system. The characterization of PMMA was confirmed by FT-IR, ^1H-NMR, GPC, DSC, and TGA techniques. Optical absorption measurements were also studied by UV-VIS technique. Transmittance and reflectance measured in the wavelength range 300-700 nm were used to calculate the optical constants. The changes in dispersion and Urbach parameters were investigated as a function of AlCl_3 content. The wide band tails increased in width and the optical energy gap decreased from 2.39 to 1.28 eV as the AlCl_3 content increased from 0% to 15%. Analysis revealed that the type of transition is the indirect allowed one.

Synthesis and Characterization of Three-Arm Poly(ε-caprolactone)-Based Poly(ester−urethanes) with Shape-Memory Effect at Body Temperature

Novel biodegradable star poly(ester−urethanes) containing three-arm poly(ε-caprolactone) (PCL) as switching segment were prepared as shape-memory polymers (SMPs) with switching temperature (Ts) around body temperature. PCL-triols with molecular weight (Mn) of 2700−4200 g/mol and Tm of 45−47 °C were synthesized in 55−67% yield by Novozym 435-catalyzed ring-opening polymerization of ε-caprolactone with glycerol as initiator, and their three-arm structures were confirmed by 1H and 13C NMR analysis. Reaction of the PCL-triols with methylene diphenyl 4,4′-diisocyanate isocynate and 1,6-hexanediol gave three-arm PCL-based poly(ester−urethane)s (tPCL-PUs) in 83−92% yield, with 65−75% soft segment. The structure of tPCL-PUs was confirmed by 1H NMR analysis, and the thermal properties were analyzed by DSC with Ts of 36−39 °C. tPCL-PUs showed excellent shape-memory effects at 38 °C during cyclic thermomechanical tensile tests: shape recovery within 10 s, shape fixity rate of 92%, and shape recovery rate of 99%. The novel biodegradable star SMPs are potentially useful in biomedical applications.

Fumaric Acid Monoethyl Ester-Functionalized Poly(d,l-lactide)/N-vinyl-2-pyrrolidone Resins for the Preparation of Tissue Engineering Scaffolds by Stereolithography

Polymer networks were prepared by photocross-linking fumaric acid monoethyl ester (FAME) functionalized, three-armed poly(D,L-lactide) oligomers using N-vinyl-2-pyrrolidone (NVP) as diluent and comonomer. The use of NVP together with FAME-functionalized oligomers resulted in copolymerization at high rates, and networks with gel contents in excess of 90% were obtained. The hydrophilicity of the poly(D,L-lactide) networks increases with increasing amounts of NVP, networks containing 50 wt % of NVP absorbed 40% of water. As the amount of NVP was increased from 30 to 50 wt %, the Young's modulus after equilibration in water decreased from 0.8 to 0.2 GPa, as opposed to an increase from 1.5 to 2.1 GPa in the dry state. Mouse preosteoblasts readily adhered and spread onto all prepared networks. Using stereolithography, porous structures with a well-defined gyroid architecture were prepared from these novel materials. This allows the preparation of tissue engineering scaffolds with optimized pore architecture and tunable material properties.

Biodegradable hydrophobic–hydrophilic hybrid hydrogels: swelling behavior and controlled drug release

The objective of this work was to investigate a new family of hydrophobic–hydrophilic biodegradable hybrid hydrogels as drug carriers. A series of hydrophobic–hydrophilic biodegradable hybrid hydrogels was formulated via photo means from hydrophobic three-arm poly (ε-caprolactone) maleic acid (PGCL-Ma) and hydrophilic dextran maleic acid (Dex-Ma) precursors over a wide range of the two precursors' feed ratio (PGCL-Ma/Dex-Ma at 100:0, 70:30, 50:50, 30:70 and 0:100). A low-molecular-weight and hydrophilic drug, the α-7 agonist cocaine methiodide, was used as the model drug for the release study from the hybrid hydrogels in pH 7.4 phosphate buffer solution at 37°C. The swelling data of these hybrid hydrogels depended on the hydrophobic to hydrophilic precursors' feed ratio, and there were several-fold differences in swelling ratios between a pure hydrophilic Dex-Ma and a pure hydrophobic PGCL-Ma hydrogels. The presence of the hydrophobic PGCL-Ma component significantly reduced the initial burst swelling of the hybrid hydrogels. Depending on the two precursors' feed ratios, the swelling data during the early period obeyed either Fickian diffusion (for 50:50 PGCL-Ma/Dex-Ma hydrogel), non-Fickian or anomalous transport (for 70:30 and 100:0 PGCL-Ma/Dex-Ma), or relaxation-controlled (for 30:70 and 0:100 PGCL-Ma/Dex-Ma). A wide range of cocaine methiodide release profiles was achieved by controlling hydrophobic to hydrophilic precursors' feed ratios. Initial drug burst release was significantly reduced as the concentration of the hydrophobic PGCL-Ma component increased in the hybrid hydrogels. The bulk of cocaine methiodide released during the 160-h period was via diffusion-controlled mechanism, while degradation-controlled mechanism dominated thereafter.