Role of chain symmetry and hydrogen bonding in segmented copolymers with monodisperse hard segments

Sheth, Jignesh P.; Klinedinst, Derek B.; Wilkes, Garth L.; Jonáš, Alexandr; Yılgör, Emel

doi:10.1016/j.polymer.2005.04.041

Cited by 154 publications

(162 citation statements)

References 11 publications

Supporting

Mentioning

151

Contrasting

Order By: Relevance

“…This induces microphase separation of the HS by crystallization or liquid-liquid demixing. 17 As expected, the morphology of SPU is strongly influenced by the molecular weight of the SS. Thus, in Figure 3 it can be seen that the SPU prepared with PTMG 650 (48 wt % of HS) shows no HS melting peak.…”

Section: Thermal Analysis (Dsc)supporting

confidence: 64%

Nanocomposites made from cellulose nanocrystals and tailored segmented polyurethanes

Auad

Mosiewicki

Richardson

et al. 2009

J of Applied Polymer Sci

View full text Add to dashboard Cite

The effect of the addition of microcrystalline cellulose nanofibers into linear segmented polyurethanes (SPU) was investigated. The polymers were synthesized with 4,4-methylene-bisphenyldiisocyanate (MDI) and poly (tetramethyleneglycol) (PTMG) with 1,4-butanediol (BD) as chain extender. The nanocrystals were introduced during the PU polymerization, which resulted in cellulose nanofibrils covalently linked to the polymer. The interactions between the cellulose nanofibrils and the matrix lead to interesting changes in the behavior of the PU, with the hard segment (HS) phase being more affected by these interactions. SPUs with different contents of HS were synthesized to better understand these effects (23 to 45 wt %). Thermal, thermo-mechanical and mechanical characterization of the nanocomposites were performed. In general, the nanocellulose favored the phase separation between the soft and hard domains generating an upward shift in the melting temperatures of the crystalline phases, an increase in the Young's modulus and a decrease in deformation at break.Comparison of the unfilled polymer responses and that of the nanocomposites showed that by increasing cellulose content, increased dynamic storage and tensile modulus as well as melting temperatures and enthalpy of melting of the soft domains can be achieved. Addition of cellulose during the polymerization essentially erased the potential shape memory behavior originally displayed by some of the SPU. However, a sample prepared by adding the cellulose nanocrystals after the reaction showed that the mechanical properties were still improved, while the shape memory behavior of the polymer was preserved.

show abstract

Section: Thermal Analysis (Dsc)supporting

confidence: 64%

Nanocomposites made from cellulose nanocrystals and tailored segmented polyurethanes

Auad

Mosiewicki

Richardson

et al. 2009

J of Applied Polymer Sci

View full text Add to dashboard Cite

show abstract

“…Hard segments mainly consist of urethane, urea, urethaneurea, amide, aramide, imide and aromatic ester groups [8][9][10][11][12][13][14][15]. Due to the presence of bidentate hydrogen bonding and their higher cohesive energy densities, segmented polyureas display better microphase separation and improved mechanical properties when compared with their polyurethane analogues [16,17]. Based on their backbone compositions, hard and soft segment type and content, segmented copolymers display broad range of properties and find diverse applications [11,[18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Multiscale Modeling of the Morphology and Properties of Segmented Silicone-Urea Copolymers

Yıldırım

Yurtsever

et al. 2011

J Inorg Organomet Polym

Self Cite

View full text Add to dashboard Cite

Molecular dynamics and mesoscale dynamics simulation techniques were used to investigate the effect of hydrogen bonding on the microphase separation, morphology and various physicochemical properties of segmented silicone-urea copolymers. Model silicone-urea copolymers investigated were based on the stoichiometric combinations of a,x-aminopropyl terminated polydimethylsiloxane (PDMS) oligomers with number average molecular weights ranging from 700 to 15,000 g/mole and bis(4-isocyanatocyclohexyl)methane (HMDI). Urea hard segment contents of the copolymers, which were determined by the PDMS molecular weight, were in 1.7-34% by weight range. Since no chain extenders were used, urea hard segments in all copolymers were of uniform length. Simulation results clearly demonstrated the presence of very good microphase separation in all silicone-urea copolymers, even for the copolymer with 1.7% by weight hard segment content. Experimentally reported enhanced properties of these materials were shown to stem from strong hydrogen bond interactions which leads to the aggregation of urea hard segments and reinforcement of the PDMS.

show abstract

“…[1][2][3][4][5][6][7][8] However, the polyurethanes with monodisperse HSs are difficult to prepare and they lose their mono-disperse distribution upon melting due to transurethane reactions. [4] Mono-disperse HS shows an enhanced thermal stability when constituted of diurethanediurea-diamide since trans-reactions do not change the distribution of these HSs.…”

Section: Introductionmentioning

confidence: 99%

Polyurethanes with Narrow‐ and Polydisperse Hard Segment Distributions

Gaymans

2008

Macro Materials & Eng

View full text Add to dashboard Cite

Polyurethanes with narrow‐disperse (ND) and polydisperse (PD) hard segment (HS) distributions were prepared in a two‐step process. First, a poly(propylene oxide) end‐capped with MDI (4,4′methylenebis(phenyl isocyanate) was synthesized. To this prepolymer either a diamine–diamide was added to form ND HSs or a mixture of a diamine–diamide and additional MDI to form PD HSs in the copolymers. The polyurethanes displayed a ribbon‐like crystalline morphology, and it was found that the copolymers with ND HSs were more crystalline, had a higher modulus, a less temperature‐dependant modulus, and a higher melting temperature than their PD counterparts. Overall, the polyurethanes with the narrow‐dispersed HSs displayed superior properties.magnified image

show abstract

Role of chain symmetry and hydrogen bonding in segmented copolymers with monodisperse hard segments

Cited by 154 publications

References 11 publications

Nanocomposites made from cellulose nanocrystals and tailored segmented polyurethanes

Nanocomposites made from cellulose nanocrystals and tailored segmented polyurethanes

Multiscale Modeling of the Morphology and Properties of Segmented Silicone-Urea Copolymers

Polyurethanes with Narrow‐ and Polydisperse Hard Segment Distributions

Contact Info

Product

Resources

About