Amphiphilic Networks. 9. Surface Characterization

Park, Dongkyu; Keszler, B.; Galiatsatos, Vassilios; Kennedy, Joseph P.; Ratner, Buddy D.

doi:10.1021/ma00112a001

Cited by 48 publications

(56 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The PDMAEMA phase expands whereas the PIB phase shrinks upon contacting with water. [34][35][36][37] Both effects yield increase of the size of free volume units. The fact that this is a fast process indicates rapid reorientation of the hydrophilic PD-MAEMA segments toward the surface of free volume units in this network.…”

Section: Resultsmentioning

confidence: 99%

“…[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][34][35][36][37] As recent investigations with polyisobutylene-(PIB)-based APNs indicate, the covalently bonded immiscible hydrophilic and hydrophobic chains yield unique nanostructured molecular composites with co-continuous microphase separated morphology. [11][12][13][14][15][16]37 This special structure is most likely the major factor determining bulk and surface structure and properties obtained by contact angle measurements, 35 X-ray photoelectron spectroscopy, and atomic force microscopy 36 and the excellent biocompatibility 34 and blood compatibility 35 of PIB-based APNs. It has been demonstrated that APNs are swellable both in hydrophilic and hydrophobic solvents, [11][12][13][14][15][16][17][18][26][27][28] and the equilibrium swelling is controlled by composition.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Free Volume and Swelling Dynamics of the Poly[(2-dimethylamino)ethyl methacrylate]-l-polyisobutylene Amphiphilic Network by Positron Annihilation Investigations

et al. 1998

View full text Add to dashboard Cite

The poly [(2-dimethylamino)ethyl methacrylate]-l-polyisobutylene (PDMAEMA-l-PIB) amphiphilic network (APN), a new class of cross-linked systems, was synthesized by the use of methacrylatetelechelic PIB obtained via quasiliving carbocationic polymerization. The swelling dynamics and the free volume changes of this APN was followed by simultaneous swelling and positron annihilation measurements. It was found that the lifetime of ortho positrons (o-Ps) increases with increasing swelling ratio (R), reaches a maximum at relatively low R, and decreases to a constant value at equilibrium swelling. These findings indicate the collapse of the hydrophobic PIB domains and expansion of the hydrophilic PDMAEMA phase in the network upon contacting with water. After reaching the maximum, the decrease of the lifetime parameter is caused by filling the free volume with water in the network. A striking observation was obtained for the o-Ps formation intensity as a function of time (or swelling ratio): the intensity rapidly decreases, and it reaches a minimum at very low R, at ∼10% of the equilibrium swelling ratio, and then increases to a constant value. These phenomena reveal important aspects of the structure of the free volume in the APN and provide fundamental information about the swelling dynamics. The minimum of the o-Ps intensity is reached at around 1:1 water/monomer units molar ratio in the network. Surprisingly, a similar phenomenon was observed when the monomer itself was mixed with water. Molecular modeling by ab initio calculations indicates that a 1:1 ringlike cluster may be formed between water and DMAEMA. On the basis of these results it is concluded that the surface of the free volume units in the APN become covered with water molecules quickly by interacting with the PDMAEMA chains at the beginning of swelling. This indicates that the free volume in the PDMAEMA-l-PIB APN is not composed of independent pores but of interconnected channels which allow rapid diffusion of water molecules to cover the surface of the free volume units. This fast process results in a quick surface structure reorganization, i.e., enrichment of the surface of the channels by PDMAEMA segments leading to the corresponding rapid decrease of o-Ps formation intensity, and to the simultaneous collapse of PIB domains yielding increase of free volume in the network and positron lifetime at the beginning of swelling. Results of this study also allow us to predict that the combined method presented here, i.e., simultaneous swelling kinetics and positron annihilation investigations, can be widely applicable for gaining new information on free volume structure, swelling dynamics, and interactions between material components and swelling agents for a large variety of networks,

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Free Volume and Swelling Dynamics of the Poly[(2-dimethylamino)ethyl methacrylate]-l-polyisobutylene Amphiphilic Network by Positron Annihilation Investigations

et al. 1998

View full text Add to dashboard Cite

show abstract

“…Difunctional polyisobutylene macromonomers carrying two end methacryloyl groups were copolymerized with 2-hydroxyethyl methacrylate or N,N-dimethylacrylamide to afford amphiphilic networks. [105] These networks with 50:50 wt.-% hydrophilic/hydrophobic moeities offered excellent biocompatibility and biostability. Difunctional PEO macromonomers having methacryloyl end groups were homo-or copolymerized with MMA to afford networks suitable for biomedical applications.…”

Section: Complex Architectures Using Homopolymerizable Macromonomersmentioning

confidence: 99%

The Strength of the Macromonomer Strategy for Complex Macromolecular Architecture: Molecular Characterization, Properties and Applications of Polymacromonomers

Hadjichristidis

Pitsikalis

Iatrou

et al. 2003

Macromol. Rapid Commun.

219

209

View full text Add to dashboard Cite

The efficiency of the macromonomer (MM) synthetic strategy for the creation of nonlinear complex macromolecular architectures (miktoarm stars, α,ω‐branched polymers, random/exact comb and graft copolymers, dendritic polymers, molecular brushes) is reviewed. In addition, the solution/bulk properties and the potential applications of polymacromonomers (PMM), as well as new synthetic ideas are presented. The synthesis of macromonomers and living polymacromonomers in situ leads to many novel linear and nonlinear structures, as for example PMM‐b‐PS‐b‐PMM, (PS)2PMM. The use of multichlorosilylstyrenes as monomer/linking agents opens new ways for structures with multichain macromonomeric building blocks.The use of multichlorosilylstyrenes as monomer/linking agents opens new ways for structures having multichain macromonomeric building blocks.magnified imageThe use of multichlorosilylstyrenes as monomer/linking agents opens new ways for structures having multichain macromonomeric building blocks.

show abstract

“…In addition, their properties can be adjusted with the ratio of the two segments. [5][6][7][8][9][10] Among reported amphiphilic networks, polybutadiene and polyisobutylene are commonly employed hydrophobic segments. In this research, we chose polytetrahydrofuran (PTHF) as the hydrophobic segment and polyacrylamide (PAm) as the hydrophilic segment to synthesize a series of novel polyacrylamide-l-polytetrahydrofuran (PAm-l-PTHF) amphiphilic networks.…”

Section: Introductionmentioning

confidence: 99%

Polytetrahydrofuran amphiphilic networks. I. Synthesis and characterization of polytetrahydrofuran acrylate ditelechelic and polyacrylamide-l-polytetrahydrofuran networks

Guan¹,

Zhang²,

Wan³

et al. 2000

J. Polym. Sci. A Polym. Chem.

View full text Add to dashboard Cite

Amphiphilic Networks. 9. Surface Characterization

Cited by 48 publications

References 2 publications

Free Volume and Swelling Dynamics of the Poly[(2-dimethylamino)ethyl methacrylate]-l-polyisobutylene Amphiphilic Network by Positron Annihilation Investigations

Free Volume and Swelling Dynamics of the Poly[(2-dimethylamino)ethyl methacrylate]-l-polyisobutylene Amphiphilic Network by Positron Annihilation Investigations

The Strength of the Macromonomer Strategy for Complex Macromolecular Architecture: Molecular Characterization, Properties and Applications of Polymacromonomers

Polytetrahydrofuran amphiphilic networks. I. Synthesis and characterization of polytetrahydrofuran acrylate ditelechelic and polyacrylamide-l-polytetrahydrofuran networks

Contact Info

Product

Resources

About